Structure, construction and design method of a canal fishway

Abstract

The present invention relates to the field of fishway technology, and in particular to a method for the structure, construction, and design of a canal fishway, comprising the following steps: S1: establishing a fishway database at a hub, evaluating the swimming ability of target fish species passing through the fishway, and determining the migratory ecological characteristics of the target fish species; S2: designing a fishway scheme and determining a preliminary design scheme for the fishway structure; S3: designing a physical model of a local section of the fishway project, and conducting a physical model test of the local section of the fishway project to obtain a recommended scheme for the pool chamber structure located upstream of the eel channel in the vertical slot fishway; S4: establishing an overall model of the fishway, and conducting an overall model test of the fishway to determine the overall structural scheme of the fishway. The design method of a canal fishway in the present application provides a theoretical basis for setting up an eel channel suitable for the migration of eels and Hepu mitten crabs and a vertical slot fishway suitable for the migration of red-eyed trout and dace, thereby solving the problem of providing migration channels for eels, red-eyed trout, dace, river perch, Hepu mitten crabs, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of fishways, and in particular to a structure, construction and design method of a canal fishway. Background Art

[0002] At present, the canal is becoming more and more important as an important part of the new land-sea channel. Compared with land transportation, the canal has the advantages of low energy consumption cost, low transportation cost and high transportation efficiency. It opens up a more convenient and economical sea-going channel in the inland area, and accelerates the construction of a relatively complete Beibu Gulf port facilities system in accordance with the requirements of building a world-class port and the standards of major coastal ports and international hub ports across the country.

[0003] The construction of permanent dams on the canal divides the previously continuous river ecosystem into discontinuous environmental units. The most direct adverse impact on fish is the blockage of migration pathways. This is often devastating for migratory and semi-migratory species that require extensive migration to complete their life cycles. They are unable to reach their original breeding or feeding grounds to complete their life cycles, severely impacting their stock abundance. For species that can complete their life cycles in localized waters, this can affect genetic exchange between populations in different waters, leading to a decrease in overall genetic diversity and deterioration in fish quality. Some rare and endangered fish species may even face the risk of extinction. To ensure the migration of fish in the canal, fishway projects must be installed at the dam.

[0004] Therefore, how to provide suitable migration channels for eels, red-eyed trout, dace, perch, Hepu mitten crab, etc. has become an important problem to be overcome by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problem in the background technology of how to provide migration channels for eels, red-eyed trout, dace, perch, Hepu mitten crab, etc., and to provide a structure, construction and design method of a canal fishway.

[0006] A method for designing a canal fishway comprises the following steps:

[0007] S1: Establish a fishway database at the hub, evaluate the swimming ability of target fish species passing through the fishway, and determine the migratory ecological characteristics of the target fish species;

[0008] S2: Based on the migratory ecological characteristics of fish species and the fishway database at the hub, a fishway scheme is designed to determine the preliminary design scheme of the fishway structure. The fishways in the preliminary design scheme include eel ways and vertical slot fishways. The migratory fish in the eel way include eels and Hepu mitten crabs, and the migratory fish in the vertical slot fishway include red-eyed trout and mud carp. One end of the eel way is connected to the middle of the vertical slot fishway, and the other end extends to the bottom of the canal.

[0009] S3: Based on the preliminary design of the fishway structure, a local cross-section physical model of the fishway project is designed and tested to obtain a recommended structural scheme for the chamber located upstream of the eel passage in the vertical slot fishway.

[0010] S4: Based on the preliminary design plan and the recommended pool structure plan, establish an overall model of the fishway, and conduct an overall model test of the fishway to determine the overall structural plan of the fishway.

[0011] The present application discloses a canal fishway design method, which establishes a fishway database at a hub, evaluates the swimming ability of target fish species passing through the fishway, determines the migratory ecological characteristics of the target fish species, designs a fishway scheme, determines a preliminary design scheme for the fishway structure, confirms the layout form of the eel way suitable for the migration of eels and Hepu mitten crabs and the vertical slot fishway suitable for the migration of red-eyed trout and dace, and the structural form after the merger, and then obtains a recommended scheme for the pool chamber structure upstream of the eel way in the vertical slot fishway through a physical model test of a local section of the fishway project, and puts the recommended scheme for the pool chamber structure into the overall fishway model, and conducts an overall fishway model test to determine the preferred overall fishway structure scheme, thereby providing a theoretical basis for setting up the eel way suitable for the migration of eels and Hepu mitten crabs and the vertical slot fishway suitable for the migration of red-eyed trout and dace, thereby solving the problem of providing migration channels for eels, red-eyed trout, dace, river perch, Hepu mitten crabs, etc.

[0012] Preferably, in step S1, evaluating the swimming ability of the target fish passing through the fishway and determining the migratory ecological characteristics of the target fish include the following steps:

[0013] S11. Confirm the hub structure and the purpose of fish passage at the hub; S12. Classify the estuarine fish community based on the interaction of freshwater runoff and seawater intrusion, and obtain the classification results of fish passage; S13. Confirm the ecological habits of each fish passage based on the classification results, and determine the fish passage specifications and season based on the ecological habits of each fish, as well as formulate the initial technical parameters of the fishway, and obtain fish that meet the requirements, wherein the initial technical parameters of the fishway include the number of fishways 2, the designed flow rate of the fishway, the layout of the fishway, the structure of the fishway, the fishway inlet, the fishway outlet, the water consumption of the fishway and the operating water level of the fishway; S14. Confirm the fish passage time period of the fishway at the hub based on the fish passage season; S15. Within the fish passage time period confirmed in step S14, conduct a swimming ability test on the fish obtained in step S13 at the hub, and obtain the swimming ability test results of different fish to clarify the migratory ecological characteristics of the fish passage objects in the hub.

[0014] Preferably, the design flow rate of the fishway includes the flow rate through the fish orifice of the fishway, the fish-attracting flow rate at the fishway inlet, and the minimum induced flow rate in the fishway.

[0015] Preferably, the fish's current-seeking characteristics and ability to overcome current are tested, and the test indicators include induced flow velocity, critical swimming speed, and surging swimming speed. Preferably, the induced flow velocity test is specifically as follows: 10 or more fish are placed in a test annular test tank, and the flow velocity is gradually increased until half of the test fish turn in the direction upstream, at which point the flow velocity is the induced flow velocity of the test fish group; the test fish are individually placed in the still water of the test annular test tank, and the flow velocity is then gradually increased until the test fish turn in the direction upstream, at which point the flow velocity is the induced flow velocity of the individual test fish.

[0016] Preferably, the critical swimming speed test is specifically as follows: the length and weight of the tested fish are placed in the swimming area of ​​a circular test tank, and the initial flow velocity, flow velocity gradient and time gradient of the circular test tank are set; the dissolved oxygen and temperature are tested at regular intervals, and when the fish reaches the end grid of the swimming area and cannot swim, the fish is removed from the swimming area and the weight of the fish is tested. It is assumed that the swimming speed of the fish is equal to the water flow velocity, and the retention effect is ignored to calculate the critical swimming speed.

[0017] Preferably, the swimming ability of the tested Coilia scabra is similar to that of Coilia septempunctata.

[0018] Preferably, step S2 specifically includes the following steps: S21. Determine the design flow rate of the eel way and the design flow rate of the vertical slot fishway based on the ecological characteristics of the migration of fish objects and the initial technical parameters of the fishway. The design flow rate of the vertical slot fishway includes the flow rate through the fish hole / slot, the inlet fish-attracting flow rate, the outlet flow rate and the main structure flow rate of the vertical slot fishway. S22. Determine the layout positions of the vertical slot fishway and the eel way, as well as the position where the eel way connects to the vertical slot fishway based on the fishway database at the hub, the initial technical parameters of the fishway, the design flow rate of the eel way, the design flow rate of the vertical slot fishway and the tailwater position of the power station in the hub; S23: Determine the design water level at the outlet of the vertical slot fishway based on the layout positions of the vertical slot fishway and the eel way, the design water storage level of the hub and the water level fluctuation parameters; and determine the design water level at the inlet of the vertical slot fishway based on the average low tide level of the tidal river section downstream of the hub, the water level fluctuation and the cumulative frequency of low tides below the hub gate; S24: Determine the design water level at the outlet of the vertical slot fishway based on the layout positions of the vertical slot fishway and the eel way, the design water storage level of the hub and the water level fluctuation parameters. The design water level at the vertical slot fishway outlet and the design water level at the vertical slot fishway inlet determine the angle parameters between the vertical slot fishway inlet axis and the riverbed water flow, as well as the vertical slot fishway inlet width parameters; S25: determine the vertical slot fishway width based on the vertical slot fishway inlet width parameters; S26: determine the vertical slot fishway structural parameters based on the design water level at the vertical slot fishway outlet, the design water level at the vertical slot fishway inlet, the size of the maximum fish passing object in the fish passing specifications, and the vertical slot fishway width; S27: design the eel way structure position and pile structure arrangement parameters based on the vertical slot fishway structural parameters, and obtain a preliminary design scheme for the fishway structure.

[0019] Preferably, the structural parameters of the vertical slot fishway include the fishway bottom slope, the fishway design flow velocity and the total length of the fishway. The relationship between the fishway bottom slope I, the fishway design flow velocity v and the total length of the fishway L is specifically as follows: Where I is the slope of the bottom of the fishway; n is the number of chambers; v is the design flow velocity of the fishway; g is the acceleration of gravity; is the baffle velocity coefficient; l y is the net length of the pool; k2 is the net length proportional coefficient; k1 is the number proportional coefficient; L is the total length of the fishway.

[0020] Preferably, step S3 specifically includes the following steps: S31. Designing a local cross-section physical model of the fishway project based on the preliminary design scheme, wherein the local cross-section physical model of the fishway project is designed as a normal model, and the local cross-section physical model of the fishway project is designed according to the gravity similarity criterion, and the geometric similarity, water flow motion similarity and dynamic similarity of the overall fishway model design scheme are checked; S32. Conducting a fishway cross-section model test, measuring and evaluating fishway parameters, and finding the parameters that exceed the standard and the reasons for the parameters exceeding the standard, wherein the fishway parameters include the water level difference between upstream and downstream adjacent chambers, the vertical seam velocity distribution, the flow field distribution in the chamber, the flow state in the chamber and the local water flow in the chamber, and the average water depth of each chamber, the average water level difference of each chamber, the vertical seam velocity distribution of each chamber, and the flow field distribution in the chamber; S33. After improving the reasons in S32, repeat S31-S33 until all fishway parameters meet the design requirements, and form a recommended chamber structure scheme based on the fishway parameters.

[0021] Preferably, in step S31, based on the preliminary design scheme of the vertical slot fishway, the design bottom slope I of the pool chamber, the average low tide level at the estuary, the operating water level at the vertical slot fishway outlet, and the minimum water depth in the pool chamber are determined; the corresponding upstream design low water level condition of the fishway, the corresponding downstream design low water level condition of the fishway and the most unfavorable design condition are determined, and based on the design bottom slope I of the pool chamber, the average low tide level at the estuary, the operating water level at the vertical slot fishway outlet, the minimum water depth in the pool chamber, the corresponding upstream design low water level condition of the fishway, the corresponding downstream design low water level condition of the fishway and the most unfavorable design condition, a local section physical model of the fishway project is designed, wherein the most unfavorable design condition is the condition where the volume of the energy dissipation water body is minimum on the basis of unchanged geometric scale of the pool chamber.

[0022] Preferably, in step S32, when conducting the fishway cross-section model test, the upstream flat water channel and the downstream overflow plate are respectively used to control the upstream and downstream water levels to be constant, and several water gauges are arranged along the fishway cross-section model to measure the water level in the pool chamber, and the flow field in the pool chamber and the vertical slit is collected at a single point using an acoustic Doppler flow meter.

[0023] Preferably, in step S32, the flow velocity distribution of the vertical seam is evaluated as follows: flow velocity is measured for at least part of the vertical seams, a plurality of measuring points are arranged at vertical intervals along the water depth on the center line of each vertical seam, and the flow velocity distribution and average flow velocity of the vertical seam are obtained based on the measuring points; a recommended range of the flow velocity distribution of the vertical seam and a recommended average flow velocity value are obtained based on the swimming ability test results of the target fish species; it is evaluated whether the flow velocity distribution of the vertical seam exceeds the recommended range of the flow velocity distribution of the vertical seam, and whether the average flow velocity of the vertical seam is greater than the recommended average flow velocity value of the vertical seam; a baffle flow velocity coefficient is obtained based on the average flow velocity of the vertical line of the fish-passing vertical seam, the average water level difference of the baffle, the average flow rate of the fishway and the water volume of the pool chamber. And the power dissipation E of the unit water in the pool, and the baffle velocity coefficient And the unit water power dissipation E of the pool chamber meets the design requirements.

[0024] Preferably, the vertical slots in the vertical slot fishway allow the liquid flow rate to pass through to be in the range of 0.54 to 1.37 m / s, and the average flow rate is 1.0 m / s.

[0025] Preferably, in step S32, the flow field distribution in the pool chamber is evaluated as follows: a pool chamber is selected to measure its surface flow field distribution, N measuring lines are set along the width of the pool chamber, and L measuring points are arranged along the length of the pool chamber on each measuring line; based on the test results of the measuring points, the mainstream entry form, mainstream path, circulation position and integrity of the recirculation zone of the pool chamber are evaluated, wherein the influence range K3 of the recirculation zone and the maximum flow velocity v of the recirculation zone are used to evaluate the flow field distribution on the surface of the pool chamber; cmax to quantify the impact of recirculation zones on fish.

[0026] Preferably, the minimum value of the mainstream flow in the pool chamber and the average flow velocity of the vertical seams are obtained based on the test results of the measuring points, and the energy dissipation rate of the pool chamber is reflected by the ratio of the minimum value of the mainstream flow in the pool chamber to the average flow velocity of the vertical seams, so as to obtain the energy dissipation rate of the pool chamber of the design scheme.

[0027] Preferably, the influence range K3 of the recirculation zone and the maximum flow velocity v of the recirculation zone are cmax To quantify the impact of the recirculation zone on fish, specifically:

[0028] K3=L c B c / (LB), where L c is the maximum length of the recirculation zone, B c is the maximum width of the recirculation zone.

[0029] Preferably, when the influence range of the recirculation zone is too large, at least a second diversion angle and a third diversion angle are set based on the diversion angle at the vertical seam in the preliminary design scheme, and the second diversion angle and the third diversion angle are respectively substituted into the local section physical model of the fishway project to form a new local section physical model of the fishway project, and a new fishway section model test is carried out to obtain the average flow velocity of the vertical seam at each diversion angle, the maximum flow velocity of the vertical seam, and the minimum flow velocity of the vertical seam, and obtain an optimized structural scheme, wherein the second diversion angle and the third diversion angle are both greater than the diversion angle at the vertical seam in the preliminary design scheme.

[0030] Preferably, the water level difference in the pool chamber, the vertical seam flow velocity distribution and the flow field distribution in the pool chamber are calculated based on the optimized structural scheme, and it is confirmed whether the water level difference in the pool chamber, the vertical seam flow velocity distribution and the flow field distribution in the pool chamber meet the design requirements. If so, the optimized structural scheme is the recommended scheme for the pool chamber structure.

[0031] Preferably, the influence range K3 of the recirculation zone is 0.12-0.17; the recirculation intensity range is 0.18-0.24 m / s.

[0032] Preferably, step S4 specifically includes the following steps: S41: establishing a fishway overall model design scheme based on the preliminary design scheme and the recommended pool chamber structure scheme; S42: making a fishway overall model based on the fishway overall model design scheme; S43: conducting a fishway overall model test based on the fishway overall model, optimizing the fishway overall layout structure scheme and operation scheme, and thus obtaining the final fishway overall structure scheme.

[0033] Preferably, the overall model of the fishway is designed as a normal model, and the overall model of the fishway is designed according to the gravity similarity criterion. The overall model design scheme of the fishway is checked for geometric similarity, water flow similarity and dynamic similarity to form an optimized design scheme of the overall model of the fishway.

[0034] Preferably, in step S42, the plane lofting of the overall fishway model adopts a plane wire control system.

[0035] Preferably, step S41 specifically includes the following steps: establishing a basic structural scheme for the overall model design of the fishway based on the preliminary design scheme; establishing a pool chamber structure scale scheme based on the optimized local section structure scheme of the fishway project, and adding the pool chamber structure scale scheme to the basic structural scheme for the overall model design of the fishway to obtain the overall model design scheme of the fishway; selecting experimental working conditions according to the design operating water level upstream of the fishway and the design operating water level downstream of the fishway; conducting overall model tests of the fishway based on the production of the overall model of the fishway and various experimental working conditions to obtain the water depth in each pool chamber and the average drop between pool chambers in each working condition.

[0036] Preferably, the experimental operating conditions include the upstream highest operating water level condition, the upstream lowest operating water level condition, the downstream lowest operating water level condition, the condition where the inlet water depth is consistent with the outlet water depth when the upstream highest water level is reached, and the highest operating water level condition.

[0037] Preferably, the vertical slot flow rate, the flow rate and flow pattern in the pool chamber, the flow rate and flow pattern in the rest pool, and the flow rate and flow pattern in the inlet and outlet of the vertical slot fishway under various working conditions are obtained based on the overall model test of the fishway.

[0038] Preferably, when the flow rate in the vertical slits in the fishway body and the fish pond exceeds the design requirements, the flow rate of the vertical slit fishway body is reduced to adapt to the water depth of the lower section of the fishway chamber under low water level conditions.

[0039] Preferably, when the vertical seams in the fishway body and the flow velocity in the fish pond exceed the design requirements, the water depth of the pool where the flow velocity exceeds the standard is increased and the flow velocity is reduced.

[0040] Preferably, when the flow rate at the fishway inlet is too low, a water replenishment device is provided at the inlet.

[0041] The present application also discloses a structure of a canal fishway, which is designed by the design method of the canal fishway of the present application. The structure of the canal fishway includes an eel way and a vertical slot fishway. The migratory fish in the eel way include eels and mitten crabs, and the migratory fish in the vertical slot fishway include red-eyed trout and grass carp. The eel way and the vertical slot fishway are located on the same side of the canal, one end of the eel way is connected to the middle of the vertical slot fishway, and the other end extends to the bottom of the canal. A climbing matrix is ​​provided in the eel way, and a part of the vertical slot fishway located upstream of the eel way is interspersed with water retaining structures, and a pool chamber is formed between adjacent water retaining structures. The water retaining structure includes relatively arranged partitions and guide plates, the width of the guide plates is smaller than the partitions, and a vertical slot for fish to pass through is provided between the partitions and the guide plates. A climbing matrix is ​​also provided in the pool chamber, and the climbing matrix includes a plurality of rows of pile structures, wherein each row is interspersed with at least two pile structures, and adjacent rows of pile structures are staggered along the length direction of the eel way and the vertical slot fishway.

[0042] The structure of a canal fishway in the present application provides climbing assistance for eels by staggering adjacent rows of pile structures along the length direction of the eel way or vertical slot fishway. At the same time, compared with the bristle base, the pile structure does not have bristles, so there is no debris blockage and it is easy to clean. Moreover, the pile structure can dissipate energy by friction resistance, water flow counteraction and diffusion along the way, thereby improving the flow state and reducing the flow velocity in the vertical slot passing through the fish.

[0043] The present application also discloses a fishway construction method for forming the structure of the canal fishway of the present application, comprising the following steps: S1: constructing a vertical slit fishway; S2: constructing an eel way and connecting the eel way with the vertical slit fishway; S3: adjusting the slope and diversion angle of the eel way.

[0044] The present invention discloses a fishway construction method based on the canal fishway design method. The method involves first constructing a vertical slot fishway, then constructing an eelway, and finally adjusting the eelway slope and diversion angle. The entire process is simple and cost-effective.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The structure of a canal fishway in the present application solves the problem of providing migration channels for eels, red-eyed trout, dace, river perch, Hepu mitten crab, etc. by setting up an eel channel suitable for the migration of eels and Hepu mitten crabs and a vertical slit fishway suitable for the migration of red-eyed trout and dace. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is the correlation between various fish and body length in this application; among them, Figure 1 a The correlation between the flow velocity and body length of eels; Figure 1 b The correlation between the critical swimming speed of eels and their body length; Figure 1 c The correlation between the eel's swimming speed and body length; Figure 1 d The correlation between the induced flow velocity and body length of Lateolabrax japonicus; Figure 1 e. The correlation between critical swimming speed and body length of Lateolabrax japonicus; Figure 1 f The correlation between the lunging swimming speed and body length of Lateolabrax japonicus; Figure 1 g The correlation between the induced flow velocity and body length of red-eyed trout; Figure 1 h The correlation between critical swimming speed and body length of red-eyed trout; Figure 1 j The correlation between the swimming speed of red-eyed trout and its body length; Figure 1 k The correlation between the induced flow velocity and body length of dace; Figure 1 The correlation between critical swimming speed and body length of m. Figure 1 nCorrelation between the lunging swimming speed and body length of dace.

[0048] Figure 2 This is a schematic diagram of the optimized fishway layout for this application.

[0049] Figure 3 This is a schematic diagram of the vertical slit pool chamber structure for this application.

[0050] Figure 4 This is a schematic elevation diagram of the Eel Road for this application.

[0051] Figure 5 For this application, the Eel Road floor plan.

[0052] Figure 6 Schematic diagram of the confluence of the eel pass and vertical slot fishway for this application.

[0053] Figure 7This is a schematic diagram of the local model scope of this application.

[0054] Figure 8 This is a schematic diagram of the water level distribution along the pool chamber of this application.

[0055] Figure 9 This is a schematic diagram of the vertical distribution of flow velocity in the vertical seam of this application. Figure 9 a is a schematic diagram of vertical measurement point distribution, Figure 9 b is a schematic diagram of the vertical distribution of flow velocity.

[0056] Figure 10 This is a schematic diagram of the distribution of flow velocity measurement points in the pool room for this application.

[0057] Figure 11 This is a schematic diagram of the flow pattern in the chamber of the preliminary design of the fishway structure for this application, where: Figure 11 a is a schematic diagram of the flow pattern in the pool chamber of the preliminary design of the fishway structure in this application. Figure 11 b is a vector diagram of the flow pattern and flow field in the pool chamber of the preliminary design scheme of the fishway structure of this application.

[0058] Figure 12 Schematic diagram of flow velocity distribution along different measuring lines in this application (Vx and Vy are vectors, ∑V is a scalar, and θ is the angle with the positive x-axis).

[0059] Figure 13 This is a schematic diagram of the plan structure of the pool chamber in the recommended pool chamber structure scheme for this application.

[0060] Figure 14 Schematic diagram of vertical distribution of flow velocity in the vertical slot of a single-sided vertical slot fishway under different diversion angles in this application.

[0061] Figure 15 Schematic diagram of vertical distribution of flow velocity in vertical slots for different fishway schemes in this application.

[0062] Figure 16 Schematic diagram of the typical flow field in the pond chamber for different fishway schemes in this application.

[0063] Figure 17 The distribution of mainstream flow velocity along the fishway chamber for different fishway schemes in this application.

[0064] Figure 18 This is the schematic diagram of the pool room layout recommended for this application, where: Figure 18 a is the schematic diagram of the pool room layout for the recommended solution of this application. Figure 18 b is a schematic diagram of the three-dimensional layout of the pool room recommended for this application.

[0065] Figure 19 This is a schematic diagram of the water level distribution along the pool chamber for the recommended solution for this application.

[0066] Figure 20This is a schematic diagram of the vertical distribution of flow velocity in the vertical seams of the recommended solution for this application.

[0067] Figure 21 This is the schematic diagram of the flow field distribution in the pool chamber recommended for this application, where: Figure 21 a is a schematic diagram of the flow field distribution in the pool chamber recommended for this application. Figure 21 b is a schematic diagram of the flow field vector in the pool chamber of the recommended solution for this application.

[0068] Figure 22 The velocity distribution along the different measuring lines of the recommended solution for this application (Vx and Vy are vectors, ∑V is a scalar, and θ is the angle with the positive x-axis).

[0069] Figure 23 This is a schematic diagram of the overall model layout of the fishway in this application.

[0070] Figure 24 This is a schematic diagram of the planar structural dimensions of the pool chamber for this application.

[0071] Figure 25 This is a schematic diagram of the water level along the fishway under various working conditions in the design scheme of this application.

[0072] Figure 26 Schematic diagram of vertical seam flow velocity under various working conditions of the design scheme for this application.

[0073] Figure 27 This is a schematic diagram of the water flow pattern in the pool chamber of this application.

[0074] Figure 28 Schematic diagram of the changes in the mainstream flow velocity in the pool chamber under various working conditions of this application.

[0075] Figure 29 This is a flow diagram of the 4# rest pool for this application.

[0076] Figure 30 This is a flow diagram of the rest pool and observation room channel for this application, where: Figure 30 a is a flow diagram of the 3# rest pool and the observation room channel. Figure 30 b is a schematic diagram of the flow pattern in the 1# and 2# rest pools and the observation room channel. Figure 30 c is a schematic diagram of the actual flow state at the inlet of the vertical slot fishway in this application.

[0077] Figure 31 This is a schematic diagram of the preferred arrangement of the pile structure in the eel channel of this application.

[0078] Figure 32 This is a schematic diagram of the flow field near the inlet and outlet of the vertical slot fishway in this application, where: Figure 32 a is a schematic diagram of the flow field near the entrance of the vertical slot fishway. Figure 32 b is a schematic diagram of the flow field near the vertical slot fishway exit.

[0079] Figure 33 This is the layout diagram of the vertical slot fishway for Optimization Scheme 1 of this application.

[0080] Figure 34 This is a schematic diagram comparing the vertical seam flow rates of the optimized solution 1 and the design solution for working condition 1 of this application.

[0081] Figure 35 This is a schematic diagram comparing the water surface lines along the fishway of the optimized solution 1 and the design solution for working condition 4 of this application.

[0082] Figure 36 This is the layout diagram of the vertical slot fishway for optimized solution 2 of this application.

[0083] Figure 37 This is a schematic diagram of the water level along the fishway under various working conditions for the optimized solution 2 of this application.

[0084] Figure 38 Schematic diagram of vertical seam flow velocity under various working conditions for optimization scheme 2 of this application.

[0085] Figure 39 Schematic diagram of the mainstream flow velocity in each working chamber of the optimization scheme 2 of this application.

[0086] Figure 40 This is a schematic diagram of the inlet flow pattern of the optimized solution for this application. DETAILED DESCRIPTION

[0087] The present invention will be further described in detail below with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments, as all technologies implemented based on the present invention fall within the scope of the present invention.

[0088] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship such as "up", "down", "left", "right", "center", "inside", "outside", etc. are based on the expression of the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the invented product / device / apparatus is placed when it is usually used. These terms of orientation or position relationship are merely for the purpose of facilitating the description of the scheme of the present invention or simplifying the description in the specific embodiments to facilitate the rapid understanding of the scheme by technicians, and do not indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore should not be understood as limiting the present invention. In addition, the use of terms such as "horizontal", "vertical", "overhanging", and "parallel" does not mean that the corresponding device / component / element is absolutely horizontal, vertical, overhanging, or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simplified to mean that the corresponding devices / components / elements are arranged in a "horizontal," "vertical," "overhanging," "parallel," and other directions, and can have an error / deviation of ±10% relative to the corresponding direction, more preferably within an error / deviation of ±8%, more preferably within an error / deviation of ±6%, more preferably within an error / deviation of ±5%, and more preferably within an error / deviation of ±4%. As long as the corresponding devices / components / elements are within the error / deviation range, they can still perform their functions in the scheme of the present invention. In addition, the use of expressions such as "first," "second," and "third" in the terminology is merely used to distinguish between identical or similar components and should not be understood to emphasize or imply the relative importance of specific components. Furthermore, in the description of the embodiments of the present invention, "several," "multiple," and "several" represent at least two. It can be any number, such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9. Furthermore, in the description of the technical solution of the present invention, unless otherwise expressly specified, defined, or limited, the terms "disposed," "installed," "connected," "connected," "provided with," "laid," and "arranged" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections. They may be welded, riveted, bolted, threaded, or other commonly used connection methods in the art. Such connections may be mechanical, electrical, or communicative; they may be direct, indirect via an intermediate medium, or internally connected between two components.

[0089] Example 1

[0090] like Figure 1-Figure 40 As shown, the method for designing a canal fishway according to this embodiment includes the following steps:

[0091] 1. Study the swimming ability of target fish species passing through the fishway to clarify the migratory ecological characteristics of the target fish species at the hub.

[0092] The fishway primarily caters to downstream migratory species such as the spotted eel (CA), eel, and spotted sea bass; anadromous species such as the seven-thread anchovy (AN) and spotted shad (AN), as well as historically distributed freshwater species such as the red-eyed trout and dace. Other estuarine species include the spotted shad, Chinese snakehead, spotted tongue goby, whitebait, tongue goby, and half-winged Chinese mitten crab, as well as the Hepu mitten crab. The fishing season is from November to September. Vertical slot fishway 23 primarily caters to fish of 40 to 600 mm in diameter, while eelway 24 caters to fish of 100 to 500 mm in diameter.

[0093] By conducting swimming ability tests on major fish species such as sea bass, eel, red-eyed trout, and dace, as well as fish currently distributed in this section of the river, the design indicators of the fishway at the hub were comprehensively determined: the flow rate range of the fish holes / slits of the vertical slot fishway 23 is 0.54~1.37m / s, and the average flow rate can be about 1.0m / s; the average flow rate of the pool chamber 30 is 0.24~0.67m / s; the inlet fish-attracting flow rate should not be lower than the fish-sensing flow rate of 0.2m / s, and should be 0.35~0.73m / s; the outlet flow rate should not be still water, and should be 0.24~0.35m / s; eels are fish with climbing habits, so the eel way 24 should not be simply designed based on the measured swimming ability, but can be designed with a steeper slope, but staggered cylindrical tubes or piers should be designed at the bottom to provide a foothold for their climbing.

[0094] 2. Design of fishway 2 scheme: propose a preliminary design scheme of the fishway structure, which includes the preliminary design scheme of the fishway plane and the structural layout of pool chamber 30.

[0095] The fishway at hub 1 adopts a left-bank double fishway scheme, with the vertical slot fishway 23 and eel way 24 both arranged on the shore close to the tailwater of the power station 27; the eel way 24 meets the vertical slot fishway 23 near the downstream observation room 34, and then merges into the vertical slot fishway 23.

[0096] The design scheme of the vertical slot fishway 23 is: bottom slope 1:51.02, total length 458m, single inlet, bottom elevation -1.52m, single outlet, bottom elevation 7m; the fishway includes 120 chambers 30 and 4 rest pools 36, the cross-section of the chamber 30 is rectangular, the bottom slope I = 1.96%, the thickness of the partition 32 and the guide plate 35 are both 30cm, the diversion angle is 30°, no pier heads are set at the ends of the partition 32 and the guide plate 35, and they are rounded with a radius R = 15cm; the net width of the chamber 30 is 3.0m, the length of the chamber 30 is 3.6m, the design water depth h is 1.0~3.36m, the design vertical slot 31 width is 45cm, and a pile structure 22 with a diameter of 15cm and a height of 10cm is set at the bottom, with a centerline spacing of 45cm and two rows of staggered arrangements.

[0097] The design of Eelway 24 is to have seven vertical entrances facing the riverbank at the intersection of the left bank's vertical retaining wall and the downstream bank, extending vertically upward from the riverbed at a depth of -7.5 meters, with an entrance every 1 meter. The main channel is an aluminum flume 13 meters long, 0.37 meters wide, and 0.1 meters high, with a slope of 15 degrees. The flume is covered with a plastic climbing matrix 20 placed inside the flume. The matrix is ​​composed of staggered plastic tubes, and the water depth of the flume tubes is greater than 3 cm. Eelway 24 merges into the vertical slot fishway 23 at an elevation of 3.39 meters. The eels will then use this vertical slot fishway 23 to continue their upstream journey.

[0098] 3. Physical model test of local section of fishway project: Based on the preliminary design scheme, a local section model of fishway with a geometric scale of 1:4 was established, and the structural layout demonstration and optimization research of 23 pools and 30 chambers of vertical slot fishway was carried out, and a recommended scheme for the structure of pool 30 was proposed.

[0099] The preliminary design of the vertical slot fishway 23 is basically reasonable in terms of the dimensions of the chamber 30, the width of the vertical slot 31, and the main bottom slope, meeting the upstream migration requirements of the target fish. The fishway flow rate is approximately 0.50 m3 / s, and the velocity coefficient of the baffle 32 is φ = 0.97. The diversion angle is small, resulting in an average flow velocity of 1.11 m / s in the vertical slot 31, which exceeds the design requirement. The mainstream in the chamber 30 is straight and the efficiency is poor. At the same time, the circulation develops unilaterally, which can easily cause small fish to lose their way and delay their upstream migration.

[0100] To address the issue of a small diversion angle, which results in the flow conditions in the vertical slits 31 and chamber 30 not meeting the requirements for fish upstream migration, the diversion angle was adjusted and optimized with the goal of promoting the deflection of the mainstream in chamber 30 and increasing mainstream energy dissipation. After comparing multiple sets of optimization schemes, a recommended structural scheme for chamber 30 was proposed, which maintained the dimensions of chamber 30, the width of the vertical slits 31, and the bottom slope of chamber 30, while increasing the diversion angle to 45°. Under this scheme, the average water level difference in chamber 30 was 0.07m, the average flow velocity in the vertical slits 31 was 1.01m / s, and the flow velocity in the vertical slits 31 was distributed between 0.99 and 1.06m / s. The flow velocity in the vertical slits 31 met the design requirements, with a velocity coefficient of φ = 0.86. Corresponding to a design water depth of 1m, the flow rate in the vertical slits 31 was approximately 0.45m3 / s, which was approximately 7% lower than the design scheme.

[0101] 4. Overall model test of fishway: Based on the recommended scheme of the structure of chamber 30 and the plane layout design scheme of vertical slit fishway 23, a 1:15 geometric scale overall model of fishway is established, and the overall hydraulic characteristics test of vertical slit fishway 23 is carried out to propose the overall layout recommendation and operation suggestions of fishway. According to the design scheme, the flow rate of fishway is mainly controlled by the water level of the upstream reservoir. Under the working condition of reservoir water level of 8.7m, the flow rate of fishway is 0.74m3 / s; under the working condition of reservoir water level of 8.0m, the flow rate of fishway is 0.44m3 / s; under each working condition, the water depth of each chamber 30 along the way meets the design requirement of not less than 1.0m; when the water level of the reservoir is 8.7m, when the water level below the dam is lower than 0.18m, the vertical slit 31 and chamber 3 of the lower section of fishway (below 1# rest pool 36) are The flow rate at the fishway entrance generally exceeded the design requirements, with the maximum velocity at vertical slit 31 reaching 1.66 m / s and the maximum velocity at chamber 30 reaching 1.31 m / s. The flow rate at the fishway entrance gradually decreased as the downstream water level rose. The mainstream flow rate at the inlet of Condition 6 was only 0.15 m / s, failing to meet the design requirements. The flow rates at the fishway entrance for the remaining conditions ranged from 0.21 to 0.69 m / s. The flow at the fishway exit was smooth, with velocities generally within the 0.03-0.1 m / s range, meeting the design requirements. To address the excessive flow rates in the lower section of the fishway, vertical slit 31 and the chamber, a recommended overall fishway layout was proposed: lowering the fishway entrance bottom elevation from -1.52 m to -2.22 m and increasing the slope of the downstream straight section, chamber 30 (from 1.95% to 3.24%). Recommended Solution: Under operating conditions 3 and 6, the inlet flow rate is lower than the fish-sensing flow rate, making it difficult to ensure fish attraction at the fishway inlet. Water replenishment is required. The minimum replenishment flow rates for operating conditions 3 and 6 are 0.7 m³ / s and 1.0 m³ / s, respectively. If inlet water replenishment is not feasible, it is recommended to install a water propeller at the fishway inlet to meet the inlet fish attraction flow rate requirements.

[0102] The specific preferred steps are as follows:

[0103] S1: Evaluate the swimming ability of target fish species passing through the fishway and determine the migratory ecological characteristics of the target fish species.

[0104] I. Confirmation of the Hub 1 Structure: Hub 1 includes a double-line ship lock, retaining dam, spillway, bottom outlet, and power station 27. The double-line ship lock is located on the left side, with retaining dam sections located on the left and right bank slopes of the double-line ship lock and the spillway. The retaining dam is located on both sides of the upper gate of the double-line ship lock and on the bank slopes of the spillway. Four dam sections are located on the left bank of the upper gate of the double-line ship lock; four dam sections are located on the right bank of the upper gate of the double-line ship lock, two of which are gate and reservoir sections for the maintenance gates of the upper gate of the ship lock, using a span-slot arrangement. Four dam sections are located on the left bank of the spillway; and seven dam sections are located on the right bank of the spillway, one of which is the gate and reservoir section for the maintenance gates of the spillway. The seven-sluice spillway is located in the main channel, using a mid-slot arrangement. A 20.0m-long blanket is installed upstream of the spillway, with the blanket top elevation set between -8.00 and 0.00m based on the gate bottom elevation. The spillway is a broad-crowned weir with a crest elevation of 1.00m. Behind the spillway, a 1:5 slope connects to the seafloor, extending 100m long. A riprap scour channel is located at the end. The bottom-hole dam section is located on the left bank, adjacent to the powerhouse dam section and immediately to the right of the spillway. The dam has a 2.0m-wide sluice gate, 5.5m-thick piers on both sides, and a 6.5m-wide half-hole spillway on the right. The dam section has a total width of 19.5m and a length of 35.0m in the direction of flow. The gate and reservoir dam section is divided into two sections: To accommodate the inspection gates of the upper gate of the double-track ship lock, the gate and reservoir section is located on the right bank of the ship lock. The gate and reservoir section is arranged across the gap, with the two dam sections integrated with the ship lock. To accommodate the inspection gates of the spillway, a gate and reservoir section is located to the right of the spillway. The dam crest elevation is coordinated with the spillway bridge and gantry crane track. Power Station 27 is a riverbed power station. The riverbed power station building is arranged on the left side of the right bank flood discharge gate. The main buildings of the power station include the water intake gate, main power station building, auxiliary power station building, installation room and tailwater channel.

[0105] 2. Based on the interaction between freshwater runoff and seawater intrusion, the estuarine fish community is classified and the classification results of fish species passing through are obtained. Based on the classification results of fish species passing through, the ecological habits of each fish species are confirmed, the number of fishways 2 is determined, the specifications of fish passages are confirmed, and fish that meet the requirements are obtained; the fish passing through the estuary include endemic species, river-sea migratory species, and semi-migratory species.

[0106] Fishway 2 is designed for multiple target fish species, including eels, Hepu mitten crabs, red-eyed trout, river perch, and dace; eels include eels and spotted eels, both of which are migratory fish from the ocean to rivers, that is, catadromous fish.

[0107] Based on a survey of fish resources in the canal's impacted areas, flower eels, moray eels, red-eyed trout, dace, river perch, and Hepu mitten crabs are listed as the primary fish species passing through the project. The ecological habits of these key fish species are as follows: Flower eels: They migrate downstream in winter to the river estuaries, where their gonads begin to develop, before entering the deep sea to spawn. Young eels migrate upstream to feed and grow in March and April each year. Eels: Originating in the sea, they migrate upstream to freshwater to grow, then return to the sea to spawn. In spring, young eels (also known as white eels or eel lines) enter the river estuaries from the sea in schools. Male eels mature in the estuaries, while female eels migrate upstream to the main streams and tributaries. Hepu mitten crabs: They are catadromous crustaceans. Their larvae metamorphose into juvenile crabs, which then migrate upstream to rivers and lakes to grow. River perch: Inhabits the mid- and lower-layers of nearshore waters, living in the saltwater-freshwater interface of estuaries and in freshwater. They typically reach sexual maturity at the age of three winters, reaching a length of 600 mm. They begin breeding in late winter, spawning in the brackish and freshwater areas of estuaries. Their breeding and migration season is primarily concentrated from February to October. Redeye trout: A mid-layer fish of rivers and streams, they are highly adaptable. They are adept at jumping and their breeding season generally runs from April to September. Their eggs are light green and sink. Mud carp: Inhabits warmer waters, which must not fall below 7°C, and overwinters in deeper waters. They belong to the mid- and lower-layers of rivers and streams. Their reproductive cycle is long, generally beginning in April or May and extending to August or September, with spawning often occurring during floods. Seven-thread anchovy: An anadromous fish, they hatch and complete their early life cycle in freshwater. Later, during their growth and development, they flexibly move between the brackish and freshwater areas of estuaries. The migration of the seven-thread anchovy is quite diverse. The flower croaker (yellow croaker) lives in brackish and freshwater areas and migrates to estuaries or inland rivers to spawn during the spawning season (April to August). The Chinese snakehead catfish can tolerate salinity levels of 0-35‰, with an optimal salinity of 10-25‰. The optimal salinity for fry is approximately 15‰. The Chinese snakehead catfish can tolerate temperatures of 6.0-35.0°C, with an ideal water temperature of 25-30°C. In summary, the main season for fish migration is February to November: flower eels and eels migrate upstream from February to April, river crabs migrate downstream from September to November, and river perch migrate from February to September.

[0108] Initial technical parameters of fishway

[0109] Based on the characteristics of fish such as eels, Hepu mitten crabs, red-eyed trout, and dace, Fishway 2 uses a double fishway design. Eels and Hepu mitten crabs use a special eelway 24. For red-eyed trout and dace, a vertical slot fishway 23 is used.

[0110] Fishway Design Flow Rate: The design principle for fishway flow rate is to ensure that the flow rate within the fishway is less than the cruising speed of the fish, allowing them to maintain their forward motion. The flow rate through the holes or vertical slits 31 in the fishway 2 must be less than the fish's burst speed, allowing them to pass through. The preferred cruising swimming speed for perch is a minimum of 55.83 cm / s and a maximum of 102.12 cm / s. The maximum swimming speed of an adult eel 0.60 m long is 1.14 m / s, while the burst speed of juvenile eels between 6 and 9 cm in length varies between 0.60 and 0.90 m / s. Field measurements show that juvenile eels between 5 and 10 cm in length prefer a flow rate of 0.18 and 0.25 m / s, with a critical flow rate of 0.45 to 0.50 m / s. Fishway flow rate design primarily involves the flow rate at the fishway orifice, the fish-attracting flow rate at the fishway inlet, and the minimum induced flow rate within the fishway. Based on the above, the design flow rate of the eel fishway is tentatively set at 0.2m / s, and the design flow rate of the fishway for fish such as red-eyed trout is tentatively set at 1m / s.

[0111] Fishway inlet design: The key lies in attracting fish from the uncontrolled natural river environment to the controlled fishway. If fish cannot be attracted to the fishway, upstream migration will be impossible. The migration routes and gathering areas of migratory fish generally follow the following rules: During upstream migration, when the flow rate of the fish's migration route is too high and they cannot continue to move against the current, they will choose to swim upstream in nearby side streams with relatively slow flow rates, mostly in the appropriate flow rate areas on both sides of the main stream of the river, or along the river bank. During migration, fish will avoid turbulence, water jumps, and whirlpools. During migration, fish will avoid oily and polluted waters and choose areas with better water quality. Juvenile fish generally have the habit of choosing sunny, windproof, and coastal areas. Based on the migration patterns of fish below the dam, the fishway inlet should be located in: areas with frequent downstream flow, immediately adjacent to the main stream; on and around the most upstream velocity barrier or upstream boundary downstream of the dam where fish can migrate upstream; in areas with smooth, straight flow and good water quality; on the bank slopes downstream of the dam; and in areas that can adapt to fluctuations in downstream water levels and ensure a water depth of at least 1.0 m at the inlet during the fish migration season. The shape of the inlet pool, the location of the auxiliary water flow diffuser, and the design of the fish ladder inlet should create a hydraulic environment with a stable flow pattern and flow rate to guide fish from the fishway inlet to the fish ladder. If there are potential influencing factors such as vortices, flow dispersion, or stagnant water, excess space in the inlet pool and fish trough should be minimized. Corners should be designed with a circular or similar shape. Furthermore, the area of ​​fish retention areas should be minimized. The fishway should be located on the right bank of the spillway, behind the dam wall, taking into account the surrounding terrain and the overall layout of the hub.

[0112] Fishway outlet design: The location of the fishway outlet must meet the following requirements: it must be adaptable to upstream water level fluctuations. During the fishing season, when the water level at the dam fluctuates, the outlet must be deep enough and well connected to the reservoir surface. The outlet should be located close to the shore, with a smooth, well-defined flow and no whirlpools, allowing fish to swim upstream smoothly along the current and the shoreline. The outlet should be away from areas with polluted water or areas that could disturb or frighten fish. The downstream requirements of upstream fish should also be considered, with the outlet facing the current to facilitate fish entry into the simulated natural channel. The fishway outlet should be located a certain distance from the power station. If it is too close, fish that have successfully migrated upstream may be swept into the turbine by the discharge water and carried downstream. If it is too far, the fish will lose their sense of the current and easily become lost. The outlet must adapt to upstream water level fluctuations, ensuring that the bottom of the outlet remains exposed under any water level fluctuations. It must also maintain a sufficient water depth, and the bottom of the fishway outlet should smoothly connect to the riverbed. The fishway outlet is controlled by a gate and connected to the upstream river channel. A preferred embodiment is as follows: the outlet of the fishway 2 is located in the reservoir area upstream of the sluice gate, and the outlet elevation is 17m.

[0113] Design an observation room 34: An observation room 34 will be installed in the fishway at Hub 1, with an observation window located in the upper middle section. This will be used to count the species and number of fish that successfully migrate upstream, assess the fish passage performance, and facilitate future improvements to the fishway structure. Due to water level fluctuations inside and outside Fishway 2, the water consumption and operating water level within Fishway 2 must be controlled to maintain a stable flow rate and flow pattern within the channel and meet the requirements of fish migration.

[0114] The ecological water consumption of Hub 1 during the dry season is 6.36m3 / s, and the ecological water consumption during the flood season is 16.74m3 / s. The water consumption of the fishway in Hub 1 is 0.8m3 / s.

[0115] Fishway Layout: Eelway 24 is located on the right bank of the spillway, after it connects to the dam wall. Its inlet is approximately 100 meters downstream of the spillway, at an elevation of -7.5 meters. Its outlet is located in the reservoir upstream of the spillway, at an elevation of 17 meters. The fishway channel is 0.5 meters wide, with a bottom slope of 16%, and a total length of approximately 150 meters. Vertical slot fishway 23 is located on the left side of power station 27. To accommodate fish migration during high and low water levels, the fishway features dual inlets, with inlet elevations of 0.34 meters and -2.02 meters, respectively. The outlet elevation is 6.5 meters. The fishway is 320 meters long when operating at high water levels and 430 meters when operating at low water levels. The fishway is 3 meters wide.

[0116] The upstream and downstream water levels of the fishway directly affect whether the fishway provides suitable conditions for fish during the fishing season. Fluctuations in the water levels upstream and downstream of the fishway can also affect the surface connection between the fishway's inlet and outlet, as well as the flow conditions in chamber 30, preventing fish from entering the reservoir and potentially preventing fish near the downstream inlet from entering the fishway. The design water level for the normal storage at the fishway outlet during the fishing season is 8.7m. The design high water level at the fishway inlet is the average high tide level of the estuary, 1.84m. The design low water level at the fishway inlet is -0.52m, the average low tide level of the estuary, with a maximum design water level difference of 9.22m.

[0117] Structure of the eel passage 24: Based on the migratory characteristics of eels (young eels) and Hepu mitten crabs (juvenile crabs), the structure of the fishway is selected as a PVC pipe trough, and a pile structure 22 is set at the bottom to provide them with good climbing space and climbing support. The friction resistance along the way brought by the pile structure 22, the water flow impact and diffusion are used to dissipate energy, thereby improving the flow state and reducing the flow velocity of the vertical slit 31 passing the fish.

[0118] Structure of the vertical slot fishway 23: Due to the significant water level difference at the downstream estuary, the fishway 23 is equipped with two inlets, one high and one low, and one outlet. The preliminary design proposal states that the total length of the fishway 23 is 431 meters, with a slope of 2.58%. The fishway 23 is 3 meters wide. Each chamber 30 is 2.2 meters long and has a designed water depth of 1.5 meters. Resting pools 36 are located every 10 to 20 chambers 30. The outlet elevation of the fishway 23 is 6.5 meters, while the lower inlet elevation is -2.02 meters and the upper inlet elevation is 0.34 meters. A gate is installed at the outlet of the fishway 23 to prevent flooding and facilitate maintenance. The side wall is 3.8m high and is equipped with a water retaining baffle 32 and a guide plate 35, both 2.7m high. A 0.2m wide vertical gap 31 is set between the baffle 32 and the guide plate 35. The water depth in the pool is 1.0m and the maximum flow rate is about 1m / s. The scale parameters and reasons of the fishway are detailed in Table 1.

[0119] Table 1: Fishway scale table

[0120]

[0121] As shown in the table above, fishway width is primarily determined by the volume of fish passing through and the size of the fish being passed. The greater the volume of fish passing through and the larger the fish being passed through, the wider the fishway should be. The net width of chamber 30 should be no less than twice the length of the main fish being passed through. The depth of the fishway is primarily determined by the habits of the fish being passed through. Demersal fish and larger adult fish require deeper water depths, and the typical depth for a fishway is 1 to 3 meters.

[0122] The width of the vertical slit 31 of the vertical slot fishway 23: The width b of the vertical slit 31 within the chamber 30 directly affects the energy dissipation efficiency of the fishway and the passability of fish. Generally, the width b of the vertical slit 31 is required to be no less than 1 / 2 the length of the fish. According to the fishway database, the width of the vertical slit 31 of ipsilateral vertical slot fishways in foreign countries is generally 1 / 8 to 1 / 10 of the chamber 30 width. In my country, the width of the ipsilateral vertical slit 31 is generally 1 / 5 of the chamber 30 width and 1 / 5 to 1 / 6 of the chamber 30 length. Therefore, the width of the vertical slit 31 is 30 cm.

[0123] Observation Room 34: Mainly used to observe the migration of fish and related data, providing a basis for future research on the migration patterns and living habits of fish and the construction of fishways.

[0124] The purpose of fish passage at Hub 1 has been confirmed: Hub 1 is located downstream of a tidal river. After the canal's construction, the river was deepened downstream to meet navigational requirements. This will exacerbate the upwelling of saltwater, leading to increased salinity in the downstream habitat. This may also increase the number of estuarine fish species migrating upstream to the locks. These fish also need to migrate between saltwater and freshwater at different stages of their life cycle. The construction of the fishway at Hub 1 provides both upstream and downstream passages. Therefore, the primary purpose of Hub 1 is to connect the migratory pathways of river-sea migratory fish, providing upstream migration conditions for estuarine fish and a migratory pathway and gene exchange for freshwater fish.

[0125] Based on the interaction between freshwater runoff and seawater intrusion, the estuarine fish community is classified into 6 ecological groups: a. Estuarine resident fish [ES]: The entire life history is carried out in estuarine waters; b. Marine occasional fish [MS]: Live in the ocean for most of the life cycle and occasionally go to estuarine waters for feeding; c. Downstream migratory fish [CA]: Mainly live in freshwater rivers and take the river as the main source of food; The estuary serves as an important migratory channel for spawning in the ocean; d. Anadromous fish [AN]: In contrast to catadromous fish, they spawn in freshwater rivers, but raise their young and forage in estuarine waters, and most adult fish live in the ocean; e. Marine migratory fish [MM]: Part of their life history occurs in nearshore waters, but estuarine waters are important foraging and raising their young, and are also important habitats for adult and juvenile fish; f. Freshwater fish [FW]: All stages of their life history are spent in the freshwater environment of the estuary's adjacent river area.

[0126] The fish species that migrate from estuaries to rivers and seas include eels, spotted eels, and spotted sea bass, while the fish species that migrate upstream include seven-thread anchovy and spotted mullet.

[0127] Three species of river-sea migratory fish in the canal—eel, spotted eel, and seven-thread anchovy—are found. Eight species of estuarine fish—spotted shad, spotted shad, spotted sea bass, Chinese snakehead, spotted tongue goby, silverfish, tongue goby, and half-ribbed Chinese fish—are found downstream of Hub 1. The canal's estuary serves as a long-distance migratory channel for eels and other fish.

[0128] After the construction of Hub 1, the downstream section will be a tidal river, and the water habitat will undergo some changes. Therefore, the main fish species passing through the fishway at Hub 1 will be downstream migratory fish [CA], upstream migratory fish [AN], and historically distributed freshwater fish.

[0129] Therefore, after the review, the main fish species to be fished are: catadromous fishes [CA], such as the spotted eel, eel, and spotted seabass; anadromous fishes [AN], such as the seven-thread anchovy and spotted mullet; and historically distributed freshwater fishes such as the red-eyed trout and dace. Concurrently, other estuarine fishes are included: the spotted mullet, Chinese snakehead, spotted tongue goby, whitebait, tongue goby, and semi-ridged Chinese fish, as well as the Hepu mitten crab. Regarding the fish species to be fished, the seven-thread anchovy and spotted mullet were adjusted to the primary fish species to be fished, while estuarine fishes such as the Chinese snakehead and spotted tongue goby were added to the secondary fish species list.

[0130] The fish passage timeframe for a fishway at the hub was determined based on the fishing season: the season runs from February to November. This timeframe was re-determined based on the reselection of fish species and their migration seasons. Juvenile eels migrate upstream in schools toward river estuaries from December to May, entering freshwater rivers. Male and female coliform anchovies have essentially identical gonadal development. Parents spawn twice annually, with the first spawning period occurring from February to March and ending in April. Parents then migrate offshore, and by May, juveniles are 40-50 mm in length. In autumn, spawning schools regroup at river estuaries for a second spawning period in August-September. The spotted mullet typically lives in brackish and freshwater areas, spawning from April to August. During the spawning season, they migrate to river estuaries or inland rivers to spawn. The tongue goby spawns from April to August. The passage season for eels and spotted eels is from December to May; for seven-line anchovies in February, March, August, and September; for striped sea bass in November to January; for spotted mullet and tongue goby in April to August; and for redeye trout and dace in April to September. In summary, the fishing season for the first fishway at the hub is from November to September, and it can be closed in October for dredging and maintenance.

[0131] Fish Size: The body length of sexually mature females ranges from 100 to 290 mm, with the smallest reaching 102 mm and weighing 4.5 g. Males range from 90 to 220 mm, with the smallest reaching 90 mm and weighing 3 g. Common lengths for spotted mullet range from 40 to 240 mm. A sexually mature three-year-old spotted sea bass reaches up to 600 mm. Young eels reaching the estuary range from 100 to 200 mm in length.

[0132] In summary, the vertical slot fishway 23 at hub 1 mainly accommodates fish of sizes ranging from 40 to 600 mm, while the eelway 24 accommodates fish of sizes ranging from 100 to 500 mm.

[0133] Swimming Ability Test: Four methods are available for testing fish swimming ability: The first involves the fish moving in a straight line in a still water tank, bait being delivered to both ends, and the fish moving back and forth. Underwater cameras are used to record the fish's movements and estimate their swimming speed and ability based on the distance and time of movement. The second involves the fish following a visual marker in a large-diameter still water annular tank, with the marker moving at speeds ranging from 0 to 4.5 m / s. The fish move in the annular tank with manually controlled water flow, and their swimming speed and ability are estimated based on their movement position and water flow rate. The third involves the fish moving in a portable annular tank with manually controlled water flow rate within a specific swimming area, and their swimming speed and ability are estimated based on the water flow rate.

[0134] Test time and location: The test time is September-October; the test location is near Hub 1.

[0135] Test fish: Based on the fish species passed through the previous phase, the re-verified fish species, and the fish availability in this canal section, the swimming ability of spotted sea bass and eels was tested, along with other fish species currently found in this section, such as red-eyed trout and dace. The design flow rate for the first fishway at the hub was determined by comparing the swimming ability of fish of similar species and size to the target fish. Test fish specifications: eels, 18.5-26.8 cm in length, average 22.0 cm; spotted sea bass, 33.0-37.0 cm in length, average 35.5 cm; red-eyed trout, 17.5-28.4 cm in length, average 22.3 cm; dace, 16.8-27.1 cm in length, average 20.8 cm. After capture, the target fish were temporarily housed in aquariums with oxygenation. To reduce stress, the fish were held for 24 hours before testing began. When the test fish needs to be transported during the test, a fine net and a bucket with water that causes less damage to the fish are used to transport the fish to reduce the impact on the test fish. Test equipment: The water tank for the fish swimming ability test is a circular test water tank for fish swimming ability. The flow rate calibration before the test uses the LGY type II propeller flowmeter. During the test, the dissolved oxygen and temperature were measured using the DO200 dissolved oxygen meter from the American YSI company. The local air pressure value was input for dissolved oxygen calibration before use. The flow rate in the water tank was gradually increased by adjusting the motor operating frequency (f, Hz). The flow rate in the water tank was tested every time the motor frequency increased by a certain frequency. A standard curve was made and linear fitting was performed. The fitting equation for the flow rate-frequency curve of the test water tank is y=0.0474x-0.036, R 2 =0.999.

[0136] Swimming Ability Indicators: There are two types of indicators that characterize fish swimming ability: current tropism and current tolerance. Current tropism refers to a fish's tendency to follow and sensitivity to currents. Current tolerance refers to a fish's ability to overcome a certain flow velocity. These two swimming ability indicators are often important reference data in fishway design and are a key focus of fishway and fish behavioral research both domestically and internationally. Specifically, fish current tropism is primarily used to design minimum flow velocities along migration routes, while fish current tolerance is primarily used to control flow velocity in fishway design.

[0137] Flow characteristics: Flow characteristics are generally measured in terms of response flow speed. This refers to the flow rate at which fish react to flow, typically indicated by a change in the direction of their movement. In fishway design, response flow speed is not only a key parameter for attracting fish at the inlet, but also serves as a reference for the minimum flow speed encountered in fishways and fish migration routes.

[0138] Current-control ability: Based on differences in the intrinsic metabolic patterns of fish and the apparent duration of their movements, fish current-control ability is divided into three main categories, expressed in terms of speed: sustained swimming speed, prolonged swimming speed, and burst speed. The differences between these three speeds in some fish can be reflected by changes in the slope of a graph showing the relationship between swimming time and speed.

[0139] A. Sustained Swimming Speed: Fish can maintain sustained swimming for considerable periods without fatigue, typically exceeding 200 minutes. During this period, aerobic metabolism provides energy, allowing red muscle fibers to slowly contract, propelling the fish forward.

[0140] B. Endurance Swimming Speed: The endurance swimming speed of fish falls between sustained and sprint swimming speeds, typically lasting 20 seconds to 200 minutes before exhaustion. At this speed, fish consume energy through both aerobic and anaerobic metabolism. While anaerobic metabolism provides higher energy, it also tends to accumulate large amounts of lactic acid, causing fatigue. The most studied critical swimming speed falls within the endurance swimming speed range.

[0141] C. Burst Swimming Speed: Burst swimming speed is the maximum speed a fish can achieve, maintained for a very short period of time, typically less than 20 seconds. At this speed, fish obtain a high level of energy through anaerobic metabolism, achieving short bursts of speed, but also accumulating waste products such as lactic acid. Burst swimming ability can be further categorized into burst swimming speed and sprint swimming speed, depending on the duration of the swim. Burst swimming speed refers to the maximum swimming speed a fish can achieve in an extremely short period of time (<2 seconds), typically used for hunting and emergency avoidance. Strike swimming speed refers to the maximum swimming speed a fish can achieve in a relatively short period of time (<20 seconds). Strike swimming speed is a key parameter in fishway design. Fish typically slow down or accelerate by adjusting the frequency and amplitude of their body and tail fin movements to maintain a gliding swimming style, which reduces energy consumption.

[0142] Fish often swim at sustained speeds (e.g., for migratory movements). They typically use endurance swimming in difficult areas and bursts of speed when hunting or escaping. Sustained movement in fish is considered a "marathon" aerobic metabolic exercise. Sustained swimming speed is the maximum speed at which a fish can swim steadily for six hours without exhaustion. Endurance swimming combines aerobic and anaerobic metabolism. The duration of endurance swimming speed generally ranges from 20 seconds to 200 minutes. The duration of endurance swimming speed is related to the species, size, water temperature, and the duration of the burst and sustained swimming cycles.

[0143] Test Content: To comprehensively investigate the swimming abilities of fish, this project tested their current-seeking characteristics and ability to overcome currents. Test indicators included: induced current velocity, critical swimming speed, and surging swimming speed.

[0144] The testing protocol is as follows: 1. Sensed Flow Rate: Sensed flow rate testing generally uses the velocity at which fish adjust their swimming direction. There are two testing methods. The first involves group testing. Ten or more fish are placed in a tank and the flow rate is gradually increased until half of the test fish turn against the current. The flow rate at this point is the sensed flow rate for the group. The second involves testing individual fish. Individual test fish are placed in a tank of still water and the flow rate is gradually increased until the test fish turn against the current. The flow rate at this point is the sensed flow rate for the individual test fish. 2. Critical Swimming Speed: There are two common methods for measuring critical swimming speed: Fixed flow rate testing: In this method, fish are kept at a constant flow rate that remains unchanged throughout the experiment. The fish are first allowed to acclimate to the tank for a period of time, and then the flow rate is adjusted to a specific desired flow rate. This increase in flow rate is completed within a specified timeframe. This procedure is repeated multiple times at different submaximal flow rates. This is done to minimize variability in fish swimming ability due to individual environmental and physiological influences. Fixed swimming speed tests all use a large number of fish of the same size and the same conditions, and require observation for a considerable period of time. Therefore, in recent years, the main method used is the incremental flow rate method, which is less time-consuming and has a small sample size. Increasing flow rate method: Before starting the experiment, the fish's body length and weight are tested and the fish are placed in the swimming area of ​​the experimental device. The initial flow rate of the experimental device is set to 1bl / s (bl is the body length of the fish), the flow rate gradient is 1bl / s, and the time gradient is 15min. The dissolved oxygen and temperature are tested every 5 minutes. When the fish is fatigued (judgment standard: the fish reaches the grid at the end of the swimming area and cannot swim), the fish is removed from the sealed area and the weight is tested. Since the fish is always swimming in the swimming area, it can be assumed that the fish's swimming speed is equal to the water flow speed. Critical swimming speed U crit For U crit =U p +(t f / t i )×U t , where: U p (bl / s) is the swimming speed of the fish during the entire time period, U t (bl / s) is the velocity gradient, t f (min) is the time it takes for the fish to accelerate to fatigue for the last time, t i (min) is the time gradient. Since the cross-sectional area of ​​the fish is less than 10% of the cross-sectional area of ​​the swimming zone, the retention effect can be ignored, meaning there is no need to correct the critical swimming speed. The incremental flow rate method has a relatively short test time, strong controllability, and requires fewer fish to obtain statistically significant values. Therefore, the incremental flow rate method was chosen to test the critical swimming speed. 3. Burst swimming speed: Because burst swimming speed is maintained for a very short time and the responses of fish are inconsistent, this embodiment uses the "incremental flow rate method" with a 20s time step to test the burst speed index value. The incremental flow rate method is the same as the critical speed test method, with a time step of 20s. The burst swimming speed, U burst, is calculated as U burst = U burst + (tf / ti) × Ut, where: Up (bl / s) is the swimming speed of the fish during the entire time period, Ut (bl / s) is the velocity gradient, tf (min) is the time it takes for the fish to increase its speed to fatigue for the last time, and ti (min) is the time gradient. Since the cross-sectional area of ​​the fish is less than 10% of the cross-sectional area of ​​the swimming zone, the retention effect can be ignored, that is, there is no need to correct the critical swimming speed.

[0145] Comprehensive Assessment of Swimming Speed: This test calculates critical swimming speed and burst swimming speed values. If 50% of the tested fish can overcome a given flow velocity, that flow velocity is considered the swimming speed index for that fish species. Comprehensive Assessment of Swimming Ability: Sustained swimming speed range, 0-80% critical swimming speed; endurance swimming speed range, 80% critical swimming speed to burst speed; burst swimming speed range, burst speed to 10 bl / s (body lengths per second). Test results, using eel, sea bass, red-eyed trout, and mud carp as examples, are detailed in Table 2:

[0146] Table 2: Test results of flow velocity, critical swimming speed and sudden swimming speed of various fish species

[0147]

[0148] Eel: Figure 1 a. Figure 1 b and Figure 1As shown in Figure c, the eel's half-endurance of critical swimming speed is 0.59 m / s, and its half-endurance of burst speed is 0.73 m / s. The upper limit of sustained swimming speed is around 80% of the critical speed, so the dividing line between sustained and endurance swimming speed is around 0.48 m / s. Based on the swimming speed range, burst speed is the lower limit of burst swimming speed, so the burst speed of 0.73 m / s is the dividing line between endurance and burst swimming speed. The upper limit of burst swimming speed is 10 bl / s.

[0149] Lateolabrax: Figure 1 d. Figure 1 e and Figure 1 As shown in figure f, the half-endurance limit of the critical speed for the Lateolabrax is 1.14 m / s, and the half-endurance limit of the burst speed is 1.37 m / s. The dividing line between sustained and endurance swimming speeds for Lateolabrax is around 0.91 m / s (1.14 m / s x 80%). The burst speed is the lower limit of the burst speed range, and the burst speed of 1.37 m / s is the dividing line between endurance and burst speeds. The upper limit of burst speed is 10 bl / s.

[0150] Red-eyed trout: Figure 1 g、 Figure 1 h and Figure 1 As shown in Figure 1, the half-endurance limit of the critical speed for red-eyed trout is 0.98 m / s, and the half-endurance limit of the burst speed is 1.45 m / s. The dividing line between the sustained and endurance swimming speeds of red-eyed trout is around 0.78 m / s (0.98 m / s x 80%). Based on the swimming speed range, the burst speed is the lower limit of the burst swimming speed, and the burst speed of 1.45 m / s is the dividing line between the endurance and burst swimming speeds. The upper limit of the burst swimming speed is 10 bl / s.

[0151] Lingru Figure 1 k. Figure 1 m and Figure 1 As shown in Figure 1, the half-endurance limit of the critical speed for dace is 1.07 m / s, and the half-endurance limit of the burst speed is 1.55 m / s. The dividing line between sustained and endurance swimming speeds for dace is around 0.76 m / s (1.07 m / s x 80%). Based on the swimming speed range, burst speed is the lower limit of burst speed, so 1.55 m / s is the dividing line between endurance and burst speeds. The upper limit of burst speed is 10 bl / s.

[0152] Swimming speed analysis: The swimming ability test results and swimming speed analysis of the tested fish are shown in Table 3.

[0153] Table 3 Swimming ability test results and swimming speed analysis

[0154]

[0155] The swimming ability test results for the razor-sharp Coilfish are used to compare the performance of the seven-thread Coilfish. With the exception of the striped seabass, the other fish tested were mostly within the acceptable fish size range. However, since the striped seabass is larger than the other fish and has stronger swimming abilities, its swimming ability is not a limiting factor. The primary controlling factor for the fishway lies in the structural dimensions.

[0156] Design Flow Velocity for the Vertical Slot Fishway 23: Flow Velocity Through the Fishhole / Slot: The boundary condition for the flow velocity control section of the vertical slot fishway 23 is to ensure a 0.10 m low-velocity area near the bottom wall of the fishhole for mid-bottom-level fish to pass through. The flow velocity in this area should be between 0.29 and 0.54 m / s. The remaining high-velocity area in the middle is primarily for large fish sprinting through, and the maximum sustained velocity is used. The flow velocity through the fishhole / slot should range from 0.54 to 1.37 m / s, with an average flow velocity of approximately 1.0 m / s. The inlet attracting flow velocity: Fish generally prefer a flow velocity within their sustained speed range, set at 60%-80% of their critical swimming speed. According to test results, the inlet attracting flow velocity should not be lower than the fish-sensing flow velocity of 0.2 m / s, and preferably be between 0.35 and 0.73 m / s. Outlet Flow Velocity: The outlet of the vertical slot fishway 23 should maintain a certain flow velocity to ensure that fish can escape without affecting their normal migratory behavior. Therefore, the outlet of the vertical slot fishway 23 should not be located in completely still water, as this would prevent fish from sensing the flow velocity and making them easily disoriented. Furthermore, the outlet should not be too close to the spillway structure. If the flow velocity exceeds the critical velocity for fish, fish will be easily sucked into the spillway and carried downstream. According to test results, the flow velocity near the fishway outlet should not be still water; a range of 0.24 to 0.35 m / s is appropriate. Flow Velocity of the Main Structure: The average flow velocity of chamber 30 should be between 0.24 and 0.67 m / s, and a low-flow area of ​​at least 0.10 to 0.30 m near the bottom wall should be maintained for fish to inhabit. The flow velocity in this area should be within 0.48 m / s.

[0157] Designed flow velocity for the eel channel 24: Currently, no eel channel 24 has been specifically designed for eels. Experiments have shown that, despite their limited swimming ability, juvenile eels can easily swim upstream at flow rates below 1.8 m / s. They are not swept away by the current, but rather swim against the current or maintain their position. Eels are climbing fish, and while their measured swimming ability is relatively low, design decisions should not be based solely on this measured ability. While the eel channel 24 can be designed with a steeper slope, staggered cylindrical tubes or piers at the bottom should provide footholds for their climbing.

[0158] In summary, the primary fish species for the Hub 1 fishway should be downstream migratory species (CA) such as the spotted eel, eel, and spotted sea bass; upstream migratory species (AN) such as the seven-lined anchovy and spotted mullet; and historically distributed freshwater species such as the red-eyed trout and mud carp. Other estuarine fish species also under consideration include the spotted mullet, Chinese snakehead, spotted tongue goby, whitebait, tongue goby, and semi-ridged Chinese fish; as well as the Hepu mitten crab. The Hub 1 fishway's season is from November to September. The primary fish species for the Hub 1 fishway range in size from 40 to 600 mm. The flow velocity through the fish holes / slits should range from 0.54 to 1.37 m / s, with an average velocity of approximately 1.0 m / s. The average flow velocity in chamber 30 should be 0.24 to 0.67 m / s. The inlet flow velocity should not be lower than the fish-sensing velocity by 0.2 m / s, preferably 0.35 to 0.73 m / s. The outlet flow velocity should not be below the still water velocity, preferably 0.24 to 0.35 m / s. Eels are climbing fish, and although their measured swimming ability is relatively low, the design should not be based solely on this measured swimming ability. The eel path 24 can be designed with a steeper slope, but staggered cylindrical tubes or piers at the bottom should provide a foothold for their climbing.

[0159] The fishway scheme is designed based on the ecological characteristics of the fish migration and the fishway database at the hub, and the preliminary design scheme of the fishway structure is determined:

[0160] Fishway 2 overall plan: Establish a fishway database at the hub. The existing fishway plans in the fishway database at the hub include the left and right bank double fishway plan, the left bank double fishway plan and the right bank double fishway plan.

[0161] In this application, the preliminary design proposal proposes a dual fishway system on both banks: Hub 1 will feature two fishways: a vertical slot fishway 23 and an eelway 24, one on each bank. Eelway 24 will be located on the right bank of the spillway, after it connects to the dam wall. Its inlet is approximately 100 meters downstream of the spillway, at an elevation of -7.5 meters, and its outlet is located in the reservoir upstream of the spillway, at an elevation of 17 meters. The fishway channel will be 0.5 meters wide, with a bottom slope of 16%, for a total length of approximately 150 meters. The vertical slot fishway 23 will be located on the left side of the power station 27. To accommodate fish migration during high and low water levels, the fishway will feature dual inlets, with inlet elevations of 0.34 meters and -2.02 meters, respectively. The outlet elevation will be 6.5 meters. The fishway will be 320 meters long for high-water level operation and 430 meters long for low-water operation. The fishway slope will be 2.85%, and the fishway width will be 3 meters.

[0162] The dual fishway schemes for both banks were subsequently reviewed and optimized, resulting in the optimized preliminary design for the left bank. After review, both the vertical slot fishway 23 and the eel way 24 were located on the left bank, close to the shore of the tailwater of the power station 27. The eel way 24 joined the vertical slot fishway 23 near the downstream observation room 34 and then merged into the vertical slot fishway 23.

[0163] Scheme Comparison: Both the left-bank and right-bank dual fishway schemes feature vertical slot fishway 23 located on the left bank. The main difference lies in the placement of eelway 24. The inlet of fishway 2 should be located near the mainstream, downstream of a physical or velocity barrier to which fish can swim upstream. In the left-bank dual fishway scheme, eelway 24 is located on the right bank of the sluice gate, where the probability of adjacent gate opening is low, limiting its effectiveness. In contrast, the left-bank dual fishway scheme places both eelway 24 and vertical slot fishway 23 on the tailwater side of the power station 27. Under most operating conditions, this is at the mainstream edge of the physical barrier (sluice gate), ensuring fish attraction and entry. In summary, the left-bank dual fishway scheme was selected for the overall preliminary design of fishway 2.

[0164] The design water level for vertical slot fishway 23 is: the design water level for Hub 1 is 8.7m, the dead water level is 8.0m, and the water level fluctuation is 0.7m. Therefore, the design water level for vertical slot fishway outlet 25 is 8.0-8.7m, with a water level fluctuation of 0.7m. The downstream section of Hub 1 is a tidal river. The design high water level for the fishway inlet is the average high tide level of 1.84m at the estuary. The design low water level for vertical slot fishway inlet 26 is the average low tide level of -0.52m at the estuary, with a water level fluctuation of 2.36m. The design inlet floor elevation is -1.31m below the low tide level, where the cumulative frequency of low tides downstream of the lock is 90%, ensuring that no waterfall forms at vertical slot fishway inlet 26.

[0165] like Figure 2 As shown, the layout principles for the vertical slot fishway inlet 26 are as follows: a. The fishway inlet should be located upstream of the sluice gate, power station 27 tailwater, ecological outfall, or near fish migration routes and frequent gathering areas, where there is a steady, straight flow. b. The fishway inlet should avoid strong vortices, backflow, dead water areas, and silt accumulation areas. c. The angle between the inlet axis and the riverbed flow should not exceed 45°. Based on the above design principles, the vertical slot fishway inlet 26 is located on the left bank of the downstream slope of the tailwater. The angle between the inlet axis and the riverbed flow is 45°, and the inlet width is consistent with the fishway width, set at 3 meters. The design low water level is the average low tide level of -0.52 meters at the estuary, and the design high water level is the average high tide level of 1.84 meters at the estuary, with a water level difference of 2.36 meters. The cumulative frequency of low tides downstream of the sluice gate is 90%, with the low tide level at -1.31 meters. Design an inlet with a floor elevation of -1.52m and a wall height of 6m. Ensure that there is no waterfall at 90% of low tides and no submergence at high tides. The operating water depth range is 1m to 3.36m.

[0166] like Figure 2As shown, the layout principles for vertical slot fishway outlets 25 are as follows: a. The outlet should be located in an area with smooth external flow and no circulation to facilitate fish upstreaming. b. The outlet should be designed in conjunction with operational management, avoiding areas where floating debris accumulates, docks, swimming areas, recreational boats, and other areas. It should also be far away from various water inlets and intakes, and the entrances to navigational structures. c. The angle between the outlet axis and the riverbed flow should not exceed 45°. d. The outlet should be open and can be equipped with facilities such as pollution interception, floating debris interception, pollution cleaning, and sewage flushing as needed. e. The outlet should be equipped with a gate to meet the operational and maintenance requirements of the fishway. Therefore, the fishway outlet is located on the left bank, approximately 150 meters upstream of the dam. The angle between the outlet axis and the riverbed flow is set at 30°. The total operating water level of the outlet is 8.0-8.7 meters, with one outlet and a floor elevation of 7 meters. The outlet should be equipped with a gate, which should be located above the flood level to prevent damage during flooding.

[0167] like Figure 3 As shown, the structural parameters of the vertical slot fishway 23 are as follows: Width of chamber 30: The width of the chamber 30 should be greater than twice the length of the fish passing object. When there are multiple types of main fish passing objects, the width should be determined based on the size of the largest fish passing object. Preferably, the specifications of the main fish passing objects are 4 to 60 cm, and the fishway width is selected to be 3 meters, which can both meet the fish passing requirements and be relatively economical. Length of chamber 30: The net length of chamber 30 can be 1.2 to 1.5 times the width of the slot body. Preferably, the length of chamber 30 is 3.6 meters. Depth of chamber 30: The water depth of chamber 30 should meet the height of the fish passing object and the energy dissipation requirements of chamber 30. The minimum water depth should be greater than 2.0 times the height of the largest fish passing object and not less than 1.0 meter. Preferably, the designed water depth h is 1.0 to 3.36 meters. Width of vertical slot 31 of fishway: The width of vertical slot 31 of partition 32 should not be less than 1 / 3 of the length of the fish passing object. A vertical slit 31 type partition 32 is selected. Preferably, the width B of the vertical slit 31 is 0.45m. The calculation model of the structural parameters of the vertical slit fishway 23 is as follows: I=Δh / (l y +d); n=H / Δh-1; L=n(l y +d)+m(Δl+d); Q=Bhv. In the formula, h is the allowable water level difference of the partition 32; v is the design flow velocity of the fishway; g is the acceleration of gravity; is the flow velocity coefficient of the partition 32, determined through hydraulic model tests and comprehensive analysis; I is the slope of the fishway bottom slope; h is the water level difference of the partition 32; ly is the net length of the pool 30; d is the thickness of the partition 32; n is the number of pools 30; H is the elevation difference of the bottom plate of the vertical slot fishway inlet and outlet; m is the number of rest pools 36; that is, m=k1n, k1 is the quantity ratio coefficient; l=k2l y , k2 is the net length ratio coefficient; L is the total length of the fishway; l is the net length of the rest pool 36; Q is the fishway flow rate, B is the width of the vertical slit 31; and h is the water depth.

[0168] A preferred method: v is set at 1.0 m / s; it can be set at 0.85 to 1.00, or determined through hydraulic model testing and comprehensive analysis. Due to the pile structure 22 at the bottom, a value of 0.85 is used. The calculated head difference across the partition 32 is approximately 0.0706 m. The water level difference across the partition 32 is 0.0706 m, and the thickness of the chamber 30 + partition 32 is 3.6, resulting in a bottom slope of I = 0.0196 = 1:51.02. H is 8.52 m, and h = 0.0706 m. There are 120 chambers 30, with a resting pool 36 provided every 15 to 30 chambers, and k1 is 1 / 15 to 1 / 30. The resting pool 36 should preferably have a flat bottom and be no less than twice the length of the chamber 30, with k2 ≥ 2. When the resting pool 36 is located at a bend, its length should be appropriately extended. The hub has three resting pools 36, each 6.6m long. L is the total length of the fishway; m is 3; l is 6.4; after calculation, L = 452m. Q is the flow rate of the fishway, which is 0.45-1.5m 3 / s.

[0169] Fishway Floor Structure: Eels can swim upstream through the dam via the vertical slot fishway 23. According to the preliminary design of the fishway structure, the eelway 24 and the vertical slot fishway 23 meet near the observation room 34 and then merge into the vertical slot fishway 23, forming a combined section. Therefore, the portion of the vertical slot fishway 23 located in the combined section must function as a migratory path for eels. To accommodate the climbing habits of eels, a pile structure 22 is installed at the bottom of the vertical slot fishway 23. The pile structure 22 is cylindrical, with a diameter of 15 cm and a height of 10 cm. The centerline spacing between the two cylindrical piles is 45 cm, and the piles are arranged in two staggered rows. The pile structure 22 can be made of embedded PVC pipes.

[0170] Inlet water replenishment: During the operation of the fishway, the upstream water level may be low and the downstream water level may be high. In extreme cases, the downstream inlet may have a very low flow rate due to the high water level, even less than the induced flow rate of fish. In this case, the inlet needs to be replenished with water.

[0171] When the water depth at the inlet and outlet of the fishway at hub 1 is the same, the flow velocity at the vertical seam 31 is 1m / s. However, under specific working conditions, that is, the water depth at the fishway outlet is 1m and the water depth at the inlet is 3.36m, the flow velocity at the inlet is about 0.04m / s, and the flow velocity at the first vertical seam 31 after the inlet is 0.30m / s. Therefore, water replenishment is mainly carried out at the inlet. After water replenishment, the inlet flow velocity should be greater than 0.2m / s, corresponding to a water replenishment flow rate of 1.5m 3 / s, at this time the fishway flow rate is 0.45m 3 / s. The water supply flow rate during the specific operation process is adjusted according to the actual inlet flow rate monitoring to ensure that the inlet flow rate is greater than 0.2m / s. Therefore, the maximum flow rate of the fishway + water supply operation is 1.95m 3The water inlet adopts side wall dispersed water supply, and the water outlet is intercepted by mesh to prevent fish from entering the water supply pipe by mistake.

[0172] Table 4 Fishway parameters

[0173] project parameter project parameter project parameter project parameter Fish pass type Vertical slot fishway 23 Pool room 30 length 3.6m Fishway slope 1：51.02 Rest pool 36 4 Fishway controls flow rate 1.0m / s Pool room 30 width 3m Import quantity 1 Rest pool 36 length 6.6m Fishway operation flow <![CDATA[0.45-1.5m 3 / s]]> Vertical seam 31 width 0.45m Import elevation -1.52m Export quantity 1 Fishway + water replenishment flow <![CDATA[0.45-1.95m 3 / s]]> Number of pool rooms 30 120 Fishway Chief 458m Exit elevation 7m

[0174] Design of Eelway 24: Fishway 2 consists of a vertical slot fishway 23 and an eelway 24. The vertical slot fishway inlet 26 has a floor elevation of -1.52m, but the riverbed below the lock is excavated to an elevation of -7.5m. Given that the vertical slot fishway inlet 26 is primarily located in surface waters, the addition of an eelway 24 is essential to attract fish from all water layers, particularly climbing species. Eelways 24 in the hub fishway database typically consist of a sloped channel, preferably with a gradient of 5°-45°, and a base for easy climbing.

[0175] Eel-specific bristle bases have been used in some cases and have proven effective, but the bristles are easily clogged with debris and are less effective at high flow rates. In practice, bristle bases are found to be less effective at high flow rates, prone to clogging, and difficult to clean when the water level in the downstream canal fluctuates significantly. This innovative improvement utilizes a pile structure 22 embedded in the base.

[0176] like Figure 4 As shown, the eel channel 24 inlet is set as a vertical pipe, installed at the intersection of the vertical retaining wall on the left bank and the downstream bank, and facing the bank, with 7 vertical openings climbing along the bank, serving as 7 eel inlets 33. Starting from the riverbed bottom plate at -7.5m, an eel inlet 33 is set every 1m. Figure 5 and Figure 6 As shown, the main channel is an aluminum flume 13 meters long, 0.27 meters wide, and 0.1 meters high, with a 15° slope. A lid provides a dark environment for migrating eels. Inside, a plastic climbing matrix 20 is placed, consisting of interlaced plastic tubes. The tubes are immersed in flowing water at a depth of at least 3 cm, which not only keeps the eels moist but also encourages them to climb the steep slope. The eelway 24 joins the vertical slot fishway 23 at the third resting pool 36 downstream, where the eels continue their migration upstream. An observation room 34 is located upstream of the intersection of the vertical slot fishway 23 and the eelway 24. This observation room is used to count the species and number of fish that have successfully migrated upstream, assess the fish passage efficiency, and facilitate future improvements to the fishway's structure and performance.

[0177] In summary: a. Based on the water use scheduling plan for the fishway at Hub 1, and considering that Power Station 27 operates with more constant flow than a sluice gate and is less likely to generate backflow zones due to sluice gate scheduling, after review at this stage, both vertical slot fishway 23 and eel way 24 will be located on the left bank, close to the shore of the tailwater of Power Station 27. Eel way 24 will meet vertical slot fishway 23 near downstream observation room 34 and then merge into vertical slot fishway 23. b. Vertical slot fishway 23 has a bottom slope of 1:51.02 and a total length of 458 meters. It will have one inlet at a bottom elevation of -1.52 meters and one outlet at a bottom elevation of 7 meters. The fishway includes 30,120 chambers and 364 rest pools. The cross-section of the chamber 30 is rectangular, the bottom slope of the chamber 30 is I = 1.96%, the thickness of the partition 32 and the guide plate 35 are both 30 cm, the diversion angle is 30°, no pier heads are set at the ends of the partition 32 and the guide plate 35, and the ends are rounded with a radius R = 15 cm; the net width of the chamber 30 is 3.0 m, the length of the chamber 30 is 3.6 m, the design water depth h is 1.0 ~ 3.36 m, the design vertical seam 31 is 45 cm wide, and a pile structure 22 with a diameter of 15 cm and a height of 10 cm is set at the bottom. The centerline spacing of the piles is 45 cm, and they are arranged in two rows in a staggered manner. c. At the intersection of the left bank's vertical retaining wall and the downstream bank, a vertical eelway 24 entrance is located toward the bank. Starting from the riverbed at -7.5 m, an entrance is located every 1 m, for a total of seven eel entrances 33. The main channel is an aluminum flume 13 m long, 0.37 m wide, and 0.1 m high, with a 15° slope. The flume is covered with a plastic climbing matrix 20, which consists of interlaced plastic tubes. The tubes are immersed in water at a depth of at least 3 cm. The eelway 24 merges into the vertical slot fishway 23 at an elevation of 3.39 m. The eels will then use this slot fishway 23 to continue their journey upstream. d. An observation room 34 is provided upstream of the intersection of the vertical slot fishway 23 and the eel way 24. This room is used to count the species and number of fish that have successfully migrated upstream and to evaluate the fish passage efficiency of the fishway, so as to facilitate future improvements to the structure of the fishway and its efficiency. This room also serves as a publicity and demonstration facility.

[0178] Fishway local section model test

[0179] Research Content: Model Test of a Partial Section of the Fishway. Research Content: a. Study the internal structure and flow patterns of the chambers; b. Observe the water level difference between upstream and downstream sections of adjacent chambers 30, the flow velocity, flow patterns, and localized flow phenomena through the fish gap; c. Measure the flow velocity distribution, flow patterns, and localized flow phenomena within the chambers 30; d. Determine the form of the energy dissipation structure (partition 32), the dimensions of the chambers 30 and vertical gaps 31, and formulate a recommended structural plan for the chambers 30.

[0180] Preparation of the fishway project's partial cross-section physical model: Similarity conditions: Based on the research content, the fishway project's partial cross-section physical model should be a normal model. The model design was conducted according to the gravity similarity criterion, resulting in a normal model. Taking into account the scale of the fishway structure and the model site constraints, the geometric scale of the fishway project's partial cross-section physical model was determined to be 1:4. The model should meet geometric similarity, water flow similarity, and dynamic similarity, adhering to the Froude similarity criterion. The scales are shown in Table 5.

[0181] Table 5 Scale calculation table of the physical model of the local section of the fishway project

[0182] scale Plane scale Vertical scale Flow rate scale Flow rate scale Roughness scale formula <![CDATA[λ L ]]> <![CDATA[λ H ]]> <![CDATA[λ v =λ L 1 / 2 ]]> <![CDATA[λ Q =λ L 5 / 2 ]]> <![CDATA[λ n =λ L 1 / 6 ]]> Actual scale 4 4 2 32 1.26

[0183] In addition, the model water flow must be turbulent, that is, the model Reynolds number Rem = VR / v = 46875 > 1000. Where V is the water velocity, m / s; R is the hydraulic radius, m; and ν is the kinematic viscosity of the water flow.

[0184] Scope of the local cross-section model: The local cross-section physical model of the fishway project is based on the preliminary design of the vertical slot fishway 23. In accordance with the requirements and content of the experimental research, the local model scope includes 10 pools 30 in the fishway, marked C1 to C10, 11 groups of baffles 32, marked 1# to 11# baffles 32, and guide plates 35. The upstream is connected to the flat water channel and the downstream is connected to the adjustable tail gate. The local model structure layout is shown in Figure 7 , which includes an upstream flat bottom section, a test slope section and a downstream flat bottom section that are connected in sequence.

[0185] Model Construction: During the process, the bottom slope of the fishway was controlled using the cross-section method and cast with cement. The partitions 32 and guide plates 35 were constructed from gray plastic panels and wooden boards. The pile structure 22 was constructed from PVC pipe. To facilitate observation of the flow patterns and fish migration characteristics within the chamber 30, a single side wall of the model chamber 30, serving as the observation section, was constructed from plexiglass. The roughness should meet resistance similarity requirements. Based on the design of the vertical slot fishway 23, the bottom slope of chamber 30 was designed to be I = 1.96%. The prototype chamber 30 had a net width of 3.0 m and a length of 3.6 m. The partitions 32 and guide plates 35 were both 0.3 m wide, with their ends rounded to a radius of R = 0.15 m. The vertical slot 31 was 0.45 m wide with a diversion angle of 30°. The bottom pile structure 22 had a diameter of 0.15 m and a height of 0.10 m.

[0186] Design scheme test study: According to the preliminary design scheme of vertical slot fishway 23, the bottom slope of chamber 30 is designed to be I=1.96%, corresponding to the low water level design conditions of the upstream and downstream of the fishway, the average low tide level of the estuary is -0.52m ~ the outlet operating water level is 8.0m, the minimum water depth in chamber 30 is 1m, and the volume of energy dissipation water body is the minimum value on the basis of the unchanged geometric scale of chamber 30, which is used as the most unfavorable design condition for the fishway cross-section model test. During the test, the upstream flat water channel and the downstream overflow plate are used to control the upstream and downstream water levels to be constant. 12 water gauges are arranged along the model to measure the water level of chamber 30, and the flow field of chamber 30 and vertical slot 31 is collected at a single point using an acoustic Doppler flow meter. Figure 8 As shown, the water level difference of chamber 30: the water depth of the inlet and outlet is controlled to be 1m, and the water level distribution of chamber 30 along the process is measured by water gauge to consider the influence of the inlet and outlet water flow stability. The water level characteristic values ​​of the typical chamber 30 in the middle of the model are shown in Table 6.

[0187] Table 6 Water level characteristic values

[0188] serial number C4 C5 C6 C7 C8 Water level in chamber 30 (m) 1.44 1.38 1.31 1.25 1.18 Water level difference between 30 pool rooms / 0.06 0.07 0.06 0.07 Water depth in the pool chamber 30m 0.98 0.99 0.99 1 1

[0189] It can be seen from the above table that the water surface line of chamber 30 is basically parallel to the bottom slope, the average water depth of typical chambers 30C4~C8 is 0.99m, and the average water level difference of chambers 30 at all levels is 0.065m.

[0190] Flow velocity distribution of vertical slit 31: Flow velocity was measured for 5# to 7# vertical slits 31. Four measuring points were arranged from top to bottom along the center line of each vertical slit 31 along the water depth [0.8H, 0.6H, 0.4H, 0.2H, 0.12H, H is the water depth at the vertical slit 31]. The flow velocity of the measuring points of the vertical slit 31 passing the fish is summarized in Table 7. The flow velocity distribution of the vertical slit 31 is as follows: Figure 9 .

[0191] Table 7 Flow velocity at each measuring point vertically through the fish slit 31, m / s;

[0192]

[0193] By testing the swimming ability of target fish species, it was found that the flow velocity distribution of the vertical slots 31 in the vertical slot fishway 23 was 0.54 to 1.37 m / s, with an average flow velocity of 1.0 m / s.

[0194] As can be seen from the above table, the average flow velocity of vertical seam 31 under the design scheme is 1.11 m / s, and the flow velocity range of the measuring point is between 0.78 and 1.36 m / s, which basically meets the value range requirement of 0.54 to 1.37 m / s. The average flow velocity exceeds the average flow velocity control index of 1 m / s.

[0195] Calculate the velocity coefficient of the partition 32 according to the following formula And the power dissipation E of 30 units of water in the pool room: E=ρg△hQ / V, v is the average flow velocity of the vertical slit 31; △h is the average water level difference of the partition 32; Q is the average flow rate of the fishway; V is the water volume of the pool chamber 30 (m 3 ) According to calculation, the flow rate of vertical slot fishway 23 is Q = 0.50m 3 / s, velocity coefficient of partition 32 Meets the requirements; unit water power dissipation E = 29.43W / m 3 <200W / m 3 , that is, the turbulence intensity of the water flow in the pool chamber 30 is small enough, and the size of the pool chamber 30 meets the power dissipation requirements per unit water body.

[0196] Flow field distribution in chamber 30: Taking C6 chamber 30 as an example, C6 chamber 30 is selected to measure the surface flow field distribution. Five measuring lines are marked N1 to N5 along the width of chamber 30. Each measuring line has 7 measuring points marked L1 to L7 along the length of chamber 30, for a total of 35 points. The measuring points are distributed as follows: Figure 10 .

[0197] like Figure 11 As shown in the schematic diagram of the flow field distribution in chamber 30 of the design, driven by the water level difference between the upstream and downstream sides of vertical slit 31, water flows around baffle 32, passes through vertical slit 31, and enters chamber 30 in the form of a jet, forming the main flow of chamber 30. The main flow of chamber 30 is continuous and smooth, i.e., it has a small degree of curvature. A rear circulation flow forms behind baffle 32, and a complete recirculation zone is not formed behind guide plate 35.

[0198] The flow velocity of the measuring points in the pool chamber 30 is shown in Table 8. The flow velocity distribution along the width of the pool chamber 30 along the measuring lines [N1~N5] is as follows Figure 12 .

[0199] Table 8 Measurement points and flow velocity ∑V (m / s) in chamber 30

[0200]

[0201] like Figure 12 As shown in the figure, the Vx distribution along the length of the chamber 30 shows negative values ​​for the near-wall measurement lines N1 and N5 in the front section, corresponding to backflow behind baffle 32 and guide plate 35. The negative range of Vx for measurement line N1 (0.79 ≤ x ≤ 3.04 m) and the value are both larger than those for measurement line N5 (-0.22 ≤ Vx ≤ -0.02 m / s), indicating that the backflow behind baffle 32 has a greater impact range and intensity. The ∑V distribution along the length of the chamber 30 shows that the mainstream flow is not fully diffused, and the velocity distribution is uneven along the cross-sectional width. The maximum velocity is concentrated at measurement lines N3 and N4, and the minimum mainstream value ∑V is 0.81 m / s. The energy dissipation rate of chamber 30 is reflected by the ratio of the minimum mainstream value of chamber 30 to the average velocity of vertical seam 31. The energy dissipation rate of chamber 30 in the design solution is approximately 27%.

[0202] The near-wall area provides a low velocity area to ensure that the target fish can rest, but in order to prevent small fish from getting lost and delaying their upstreaming time, a certain amount of backflow is required to meet the energy dissipation requirements, but the backflow cannot be too intense and the range cannot be too large. c is the maximum length of the recirculation zone, B c is the maximum width of the recirculation zone, v cmax is the maximum flow velocity in the recirculation zone, L is the length of the pool chamber 30, B is the width of the pool chamber 30, and the quantitative parameters of the recirculation zone are shown in Table 9.

[0203] Table 9 Reflow zone parameters

[0204] Recirculation zone location <![CDATA[L c / L]]> <![CDATA[B c / B]]> <![CDATA[L c / B c ]]> <![CDATA[L c B c / LB]]> <![CDATA[v cmax (m / s)]]> After partition 32 0.83 0.50 2.00 0.42 0.34 Guide bar 35 / / / / /

[0205] L c B c / LB can be used to define the impact range of the reflow zone, from Figure 11 As can be seen from Table 9, the backflow area behind the guide plate 35 is suppressed under the design scheme, and a stable and complete backflow is not formed. The backflow area behind the partition 32 has a large impact range, and L c B c / LB=0.42,intensity v cmax =0.34m / s.

[0206] In summary, the preliminary design of the vertical slot fishway 23 includes a rectangular chamber 30 with a bottom slope of 1.96%. The chamber 30 is 3.6 meters long, with the baffles 32 and guide plates 35 both 0.3 meters thick and a net width of 3.0 meters. The ends of the baffles 32 and guide plates 35 are rounded with a semicircular arc of 0.15 meters in radius, without piers. The vertical slot 31 for the fish passage is 0.45 meters wide, with a diversion angle of 30°. Pile structures 22 with a diameter of 15 cm and a height of 10 cm are installed at the bottom, with pile centerline spacing of 45 cm, arranged in two staggered rows. The design flow conditions were verified by constructing a local model with a geometric scale of 1:4, yielding the following conclusions:

[0207] The water surface line along the pool chamber 30 is basically parallel to the bottom slope. The average water level difference of the pool chamber 30 is 0.065m. The average flow velocity of the vertical seam 31 is 1.11m / s. The flow velocity at the measuring points is distributed between 0.97 and 1.36m / s, which basically meets the value range requirement of 0.54 to 1.37m / s. The average flow velocity exceeds the average flow velocity control index of 1m / s.

[0208] The flow rate of vertical slot fishway 23 is about 0.50m 3 / s, velocity coefficient of partition 32 Unit water power dissipation E = 29.43W / m 3 The turbulence intensity of the water flow in the pool chamber 30 is small enough, and the size of the pool chamber 30 is reasonable to meet the power dissipation requirements per unit water body.

[0209] Driven by the water level difference between chambers 30, the water flow bypasses the pier of partition 32 and enters chamber 30 through the vertical slit 31. The mainstream in chamber 30 has a small degree of curvature along the way and does not diffuse sufficiently along the width of chamber 30. The maximum flow velocity is concentrated along the N3 and N4 measuring lines, and the minimum value of the mainstream is 0.81 m / s. The average flow velocity in chamber 30 is 0.50 m / s, which meets the recommended average flow velocity range of 0.24 to 0.67 m / s for chamber 30.

[0210] There is no obvious deflection and diffusion of the mainstream in the pool chamber 30. The development of the backflow behind the guide plate 35 is suppressed and no complete and stable backflow zone is formed. However, a large-scale backflow zone is formed behind the partition 32 under the shear effect of the mainstream. cBc / LB=0.42,maximum reflux intensity v cmax =0.34m / s. A large backflow range can easily cause small fish to lose their way.

[0211] In summary, the scale of the pool chamber 30, the width of the vertical slit 31, and the main bottom slope design under the design scheme are basically reasonable and meet the requirements of the target fish for upstream swimming; the diversion angle is small, so that the mainstream injected into the pool chamber 30 through the vertical slit 31 does not undergo obvious deflection in the pool chamber 30, and the energy dissipation is not obvious, which is about 27%. The average flow velocity in the vertical slit 31 exceeds the design recommended value. At the same time, a large-scale backflow area is formed on the rear side of the partition 32, which can easily cause small fish to lose their way and delay the upstream swimming time. The flow state in the pool chamber 30 needs to be adjusted.

[0212] Optimization scheme experimental research

[0213] Overview of the optimization scheme: After the design scheme test, the diversion angle of 30° is too small, which is the main reason why the mainstream is almost vertically injected into the lower chamber 30 and the diffusion in the chamber 30 is insufficient, and the influence range of the unilateral recirculation area behind the partition 32 is too large. Therefore, the optimization idea of ​​increasing the diversion angle to promote the deviation of the mainstream in the chamber 30 is adopted. The diversion angle is optimized, and the scale of the chamber 30, the width of the vertical seam 31, the bottom slope of the chamber 30 and the arrangement of the pile structure 22 remain unchanged, and a series of optimization test studies are carried out. Based on the design scheme of 30° diversion angle, it is increased to 45° and 50° respectively, forming 45° and 50° single-side vertical seam fishway 23 schemes, and a 45° opposite-side vertical seam fishway 23 scheme is added for synchronous comparative demonstration. The characteristic structural parameters of the optimization scheme and the structure of the chamber 30 are shown in Table 10. Figure 13 .

[0214] Table 10 Characteristic structural parameters of the series of optimization schemes and vertical seam flow rates of different schemes

[0215]

[0216] Comparative analysis of schemes: Same-side vertical slot fishway scheme: In view of the unfavorable water flow conditions in chamber 30 exposed by the design scheme, such as the average flow velocity of the vertical slot 31 exceeding the design requirements and no obvious deflection of the mainstream in chamber 30, a comparative analysis of the three sets of design schemes of the single-side vertical slot fishway 23, Run1 and Run2 schemes, was conducted.

[0217] The flow rates of vertical slot 31 of three groups of vertical slot fishway 23 on the same side are shown in Table 10. Figure 14 . Compared with the design scheme, the water flow velocity in the vertical seam 31 decreases after the diversion angle increases. Among them, the average flow velocity of the vertical seam 31 in Run1 decreases more significantly, that is, when the diversion angle is adjusted to 45°, the average flow velocity of the vertical seam 31 drops from 1.11m / s in the design scheme to 1.01m / s, and the flow velocity range is 0.99~1.06m / s, which meets the design recommended flow velocity requirements. When the diversion angle is further increased to 50°, the flow velocity of the vertical seam 31 in the Run2 scheme increases compared with the Run1 scheme, and the average flow velocity of the vertical seam 31 is 1.05m / s, and the flow velocity distribution is in the range of 1~1.16m / s. At the same time, it can be seen from the vertical distribution of flow velocity that the vertical distribution of the flow velocity in the vertical seam 31 is more uniform after the diversion angle is increased.

[0218] Different-side vertical slit fishway 23 scheme: By comparing the three groups of single-side vertical slit fishway 23 schemes with different diversion angles, it can be seen that when the diversion angle is 45°, the flow velocity in the vertical slit 31 is most obviously attenuated, with an average flow velocity of 1.01m / s, which meets the flow velocity recommendations proposed in the design phase. Therefore, based on this diversion angle, in response to the design problems exposed by the design scheme, such as insufficient mainstream deflection and the flow state in chamber 30 being unfavorable for fish to swim upstream, the water flow conditions of the three groups of schemes are compared: the design scheme, the single-side vertical slit fishway 23Run1 with a 45° diversion angle, and the double-side vertical slit fishway 23Run3 with a 45° diversion angle. The flow velocity distribution of the vertical slit 31 in different schemes is shown in Table 11. Figure 15 , the typical flow field distribution under the three schemes is as follows Figure 16 .

[0219] As can be seen from the chart, for the same diversion angle, the arrangement of vertical slits 31 on opposite sides has an adverse effect on water energy dissipation. Under the Run3 scheme, the average flow velocity of vertical slits 31 reaches 1.23m / s, which is 23% higher than the design recommended average flow velocity of 1.0m / s. Figure 16 It can be seen that the mainstream in the pool chamber 30 of Run1 and Run3 schemes has obvious deflection, such as Figure 17As shown, compared with the design scheme, the mainstream in the pool chamber 30 attenuates significantly along the way, and the attenuation rate increases to about 50%. The single-sided vertical slit 31 scheme of Run1 forms a slightly curved S-shaped mainstream in the single-stage pool chamber 30, and forms a complete backflow zone behind the baffle 32 and the backflow zone behind the guide plate 35 on both sides of the mainstream. The mainstream in the pool chamber 30 shows a trend of first decreasing and then increasing, with a minimum value of 0.51m / s in the middle and lower sections of the pool chamber 30 (L6 measuring line); the opposite-side vertical slit 31 scheme (Run3) forms an S-shaped mainstream in the two consecutive pool chambers 30, and forms a backflow zone behind the baffle 32 in the single-stage pool chamber 30. The mainstream in the pool chamber 30 decreases along the way, and the mainstream minimum value of 0.60m / s appears near the lower vertical slit 31 at the downstream end of the pool chamber 30.

[0220] Table 11 Flow rate of vertical seam 31 in different schemes

[0221]

[0222]

[0223] Summary of the Optimization Scheme: In response to the design scheme test results, which showed that the average flow velocity of the vertical slot 31 slightly exceeded the design recommended value, the mainstream in chamber 30 was insufficiently deflected, and there was significant unilateral backflow behind baffle 32, all of which were unfavorable to fish upstream flow conditions, an optimization approach was adopted to increase the diversion angle to promote mainstream deflection in chamber 30. Three optimized schemes were simultaneously compared and demonstrated: a single-sided vertical slot fishway 23 with diversion angles of 45° and 50°, and a contralateral vertical slot fishway 23 with a diversion angle of 45°. Based on the test results of the three optimized vertical slot fishway 23 schemes, it was found that as the diversion angle increased, the mainstream in chamber 30 was significantly deflected compared to the design scheme (30° diversion angle), and the mainstream attenuation rate in chamber 30 increased from 23% to approximately 50%. The single-sided vertical slot fishway 23, with a diversion angle of 45°, exhibits more reasonable flow velocity distribution characteristics along the vertical slot 31 and the main flow in chamber 30 compared to other options. The average flow velocity in vertical slot 31 is reduced from the design plan's 1.11 m / s to 1.01 m / s, meeting the design's recommended flow velocity requirements for vertical slot 31. Furthermore, the main flow in the single-stage chamber 30 forms a slightly curved S-shaped curve, creating a complete and stable recirculation zone on both sides of the main flow. Therefore, the single-sided vertical slot fishway 23, with a diversion angle of 45°, chamber 30 dimensions, vertical slot 31 width, chamber 30 bottom slope, and pile structure 22 layout unchanged from the design, is recommended as the cross-sectional model for the fishway at hub 1.

[0224] Test results of the recommended solution: Solution overview: The recommended solution is that the design bottom slope of the pool chamber 30 is I = 1.96%, the net width of the prototype pool chamber 30 is 3.0m, the length of the pool chamber 30 is 3.6m, the width of the partition 32 and the guide plate 35 are both 0.3m, and the ends are rounded with a radius of R = 0.15m. The width of the vertical seam 31 is 0.45m, the diversion angle is 45°, the diameter of the bottom pile structure 22 is 0.15m, and the height is 0.10m. The layout of the pool chamber 30 is as follows Figure 18. Water level difference in pool room 30: Figure 19 As shown, the water depth at the inlet and outlet is controlled at 1m. The water level distribution of 30 chambers along the recommended scheme is measured by water gauge. Considering the influence of the water flow stability at the inlet and outlet, the water level characteristic values ​​of 30 chambers in the middle of the model are shown in Table 5.4-4.

[0225] Table 5.4-4 Water level characteristic values

[0226] serial number C4 C5 C6 C7 C8 Water level in chamber 30 (m) 1.47 1.4 1.33 1.26 1.19 Water level difference between 30 pool rooms / 0.07 0.07 0.07 0.07 Water depth in the pool chamber 30m 1 1 1 1.01 1.01

[0227] It can be seen from the above table that the water surface line of chamber 30 is basically parallel to the bottom slope. The water levels of the upstream inlet and downstream outlet of the control model are 1.71m and 1.00m respectively, that is, the water depth of the flat slope section is maintained at 1.00m. The average water depth of chambers C4 to C8 is 1.00m, and the average water level difference of chambers 30 at all levels is 0.07m.

[0228] Flow velocity distribution of vertical slit 31: Flow velocity of 5#~7# vertical slit 31 was measured. Four measuring points were arranged at different positions along the water depth from top to bottom on the center line of each vertical slit 31, namely 0.8H, 0.6H, 0.4H, and 0.2H. H is the water depth value of vertical slit 31. The flow velocity of the measuring points of vertical slit 31 passing fish is summarized in Table 12. The flow velocity distribution of vertical slit 31 is as follows: Figure 20 .

[0229] Table 12 Flow velocity at each vertical measuring point of vertical slit 31 (m / s)

[0230]

[0231] As can be seen from the chart, under the recommended scheme, the average flow velocity of vertical joint 31 is 1.01 m / s, and the average flow velocity distribution of the measuring points is between 0.99 and 1.06 m / s, which basically meets the requirements of an average flow velocity of 1 m / s in vertical joint 31 and a flow velocity distribution range of 0.54 to 1.37 m / s.

[0232] Under the recommended solution, the flow rate of vertical slot fishway 23 is Q = 0.45m 3 / s, calculate the velocity coefficient of partition 32 The power dissipation of 30 units of water in the pool is E = 28.61W / m 3 <200W / m 3 , the size of chamber 30 meets the power dissipation requirements per unit water body.

[0233] Flow field distribution in chamber 30: Select a typical chamber 30 to measure its flow field distribution, and the measurement point arrangement is the same as the design scheme. The flow field distribution of the recommended solution chamber 30 is shown as follows Figure 21As can be seen from the figure, driven by the water level difference between the upstream and downstream of the vertical seam 31, the water flows around the baffle 32 and passes through the vertical seam 31 into the pool chamber 30 in the form of a jet to form the mainstream of the pool chamber 30. The mainstream presents an obvious S-shaped continuous curve in the pool chamber 30, and a complete and stable recirculation zone is formed on the back side of the baffle 32 and the guide plate 35. The flow velocities of the measuring points in the recommended solution pool chamber 30 are shown in Table 13. The minimum flow velocity of the mainstream occurs at measuring point L6, ∑V=0.51m / s, which is significantly lower than the minimum flow velocity of the mainstream in the design solution. That is, as the curvature of the mainstream entering the pool chamber 30 increases, the degree of mainstream attenuation increases.

[0234] Table 13 Measurement points and flow rate ∑Vm / s in chamber 30

[0235]

[0236] The flow velocity distribution along the 5 measuring lines [N1~N5] with a width of 30 in the pool is as follows Figure 22 As shown in the figure, the Vx distribution along the length of the flow path shows that the near-wall measurement lines N1 and N5 exhibit negative values ​​in the front section of chamber 30, corresponding to the recirculation zone behind partition 32 and guide plate 35. The negative Vx value for the N1 measurement line ranges from 1.24 ≤ x ≤ 2.14 m, with a value of -0.13 ≤ Vx ≤ -0.01 m / s. The negative Vx value for the N5 measurement line ranges from 1.24 ≤ x ≤ 3.04 m, with a value of -0.22 ≤ Vx ≤ -0.04 m / s. The ∑V distribution along the length of the flow path shows that the mainstream flow within chamber 30 is concentrated along the N3 and N4 measurement lines. The velocity distribution within chamber 30 is more uniform than in the design solution, indicating that the mainstream flow is effectively dissipated through the vertical slit 31 jet. The quantitative parameters of the recirculation zone for the recommended solution are shown in Table 14.

[0237] Table 14 Reflow zone parameters

[0238] Recirculation zone location <![CDATA[L c / L]]> <![CDATA[B c / B]]> <![CDATA[L c / B c ]]> <![CDATA[L c B c / LB]]> <![CDATA[v cmax (m / s)]]> After partition 32 0.38 0.33 1.36 0.12 0.18 Guide bar 35 0.5 0.33 1.82 0.17 0.24

[0239] The influence range of the backflow area behind the partition 32 is L c B c / LB=0.12, reflux intensity v cmax =0.18m / s, the influence range of the recirculation zone behind the guide plate 35 is L c B c / LB=0.17,backflow intensity v cmax =0.24m / s. Compared with the design scheme, the recommended scheme redistributes the backflow in the pool chamber 30, forming a stable and complete backflow behind the guide plate 35, and the influence range of the backflow behind the partition 32 is reduced from 0.42 to 0.12, and the intensity is attenuated from 0.34m / s to 0.24m / s.

[0240] Summary of the recommended solution: In view of the fact that the diversion angle 30° is too small as exposed in the design solution, the mainstream is almost vertically injected into the lower chamber 30, the mainstream diffusion in the chamber 30 is insufficient, and the unilateral backflow range behind the partition 32 is too large, which easily makes the target fish swim upstream and creates unfavorable water flow conditions in the chamber 30. Therefore, the diversion angle is optimized. The recommended solution for hub 1 is to keep the size of the chamber 30, the width of the vertical seam 31 and the bottom slope of the chamber 30 unchanged, increase the diversion angle to 45°, promote the deflection of the mainstream in the chamber 30, increase the energy dissipation of the mainstream, and form the optimized water flow structure of the chamber 30. The water flow conditions are demonstrated through a local model with a geometric scale of 1:4, and the following conclusions are drawn:

[0241] The water surface line along the pool chamber 30 is basically parallel to the bottom slope, the average water level difference of the pool chamber 30 is 0.07m, the average flow velocity of the vertical seam 31 is 1.01m / s, and the vertical flow velocity is evenly distributed from the top of the pile structure 22 to the free water surface. The flow velocity of the vertical seam 31 is distributed between 0.99 and 1.06m / s. The flow velocity of the vertical seam 31 passing through the fish meets the average flow velocity of 1m / s, and the flow velocity distribution range requirement of 0.54 to 1.37m / s.

[0242] The flow rate coefficient of vertical slit 31 type baffle 32 is φ = 0.86, and the power dissipation per unit water volume in chamber 30 is E = 28.61 W / m 3 <200W / m 3 , the size of the pool chamber 30 meets the power dissipation requirements of the unit water body; on the basis of the unchanged size and bottom design of the pool chamber 30, the structure of the vertical seam 31, the partition 32 and the guide plate 35 are optimized, and the flow rate coefficient Decreases, corresponding to a design water depth of 1m, the flow rate of vertical joint 31 is about 0.45m 3 / s, which is about 7% lower than the design solution.

[0243] Under the recommended scheme, the water flow is driven by the water level difference between the chambers 30, bypasses the pier of the partition 32, and enters the chamber 30 through the vertical slit 31. The mainstream in the chamber 30 is continuous, clear and S-shaped. After entering the chamber 30, the mainstream is effectively diffused. The average flow velocity in the chamber 30 is 0.37 m / s, which meets the average flow velocity range of 0.24 to 0.67 m / s in the chamber 30, and the mainstream flow velocity is ≥0.51 m / s.

[0244] The curvature of the mainstream in the pool chamber 30 increases, and a complete and stable recirculation zone with a considerable influence range and intensity is formed behind the partition 32 and the guide plate 35. The influence range of the recirculation zones on both sides is 0.12-0.17, and the recirculation intensity range is 0.18-0.24 m / s. A low flow rate zone is created near the wall, ensuring that the target fish can rest while preventing small fish from getting lost and delaying their upstreaming time.

[0245] The single-sided vertical slot fishway 23 at Hub 1 features a rectangular chamber 30 with a bottom slope of 1.96%. The chamber 30 is 3.6 meters long, with both the baffle 32 and guide plate 35 0.3 meters thick. The chamber 30 has a net width of 3.0 meters, and the vertical slot 31 is 0.45 meters wide. Piles 22 with a diameter of 15 cm and a height of 10 cm are installed at the bottom, with piles spaced 45 cm apart in two staggered rows. A partial cross-sectional model of the fishway at a geometric scale of 1:4 was established to evaluate the structural rationality of the chamber 30 and baffle 32, as well as the flow conditions. Optimization studies were conducted, resulting in the following conclusions:

[0246] Under the design scheme, the scale of the pool chamber 30, the width of the vertical seam 31, and the main bottom slope are basically reasonable, meeting the requirements of the target fish to migrate upstream; the flow rate of the fishway is about 0.50m 3 / s, velocity coefficient of partition 32 The diversion angle is small, so that the mainstream injected into the pool chamber 30 through the vertical slit 31 does not experience obvious deflection and energy dissipation in the pool chamber 30. The average flow velocity of the vertical slit 31 is 1.11m / s. After entering the pool chamber 30, the maximum flow velocity is concentrated along the N3 and N4 measuring lines, and the minimum value of the mainstream is 0.81m / s. At the same time, the development of the backflow behind the guide plate 35 is suppressed, and a complete and stable backflow zone is not formed. A large-scale backflow zone is formed behind the partition 32 under the shear effect of the mainstream. L c B c / LB=0.42, which may easily cause small fish to lose their way and delay their upstreaming time. Therefore, the flow pattern in the pool chamber 30 needs to be adjusted.

[0247] The small value of the diversion angle is the main reason why the water conditions in the vertical seam 31 and the pool chamber 30 do not meet the requirements for fish upstream migration. Therefore, with the idea of ​​promoting the deflection of the mainstream in the pool chamber 30 and increasing the energy dissipation of the mainstream, the diversion angle is adjusted to optimize the water flow structure of the pool chamber 30. The recommended solution is to keep the size of the pool chamber 30, the width of the vertical seam 31 and the bottom slope of the pool chamber 30 unchanged, and increase the diversion angle to 45°.

[0248] Under the recommended solution, the average water level difference of the pool chamber 30 is 0.07m, the average flow velocity of the vertical seam 31 is 1.01m / s, the flow velocity distribution of the vertical seam 31 is between 0.99 and 1.06m / s, and the flow velocity of the fish-passing vertical seam 31 meets the requirements of an average flow velocity of 1m / s and a flow velocity distribution range of 0.54 to 1.37m / s. On the basis of the unchanged size and bottom design of the pool chamber 30, the flow velocity coefficient is improved by recommending the structure of the vertical seam 31, the partition 32 and the guide plate 35. has decreased, For a design water depth of 1m, the flow rate of vertical joint 31 is about 0.45m 3 / s, which is about 7% lower than the design. The mainstream in chamber 30 is continuous, clear and S-shaped. After entering chamber 30, the mainstream is effectively diffused. The average flow velocity in chamber 30 is 0.37m / s, which meets the average flow velocity range of 0.24-0.67m / s in chamber 30, and the mainstream flow velocity is ≥0.51m / s. The curvature of the mainstream in chamber 30 increases, and a complete and stable recirculation zone with a considerable influence range and intensity is formed behind the partition 32 and the guide plate 35. The influence range of the recirculation zone on both sides is 0.12-0.17, and the recirculation intensity range is 0.18-0.24m / s. A low flow velocity zone is created near the wall to ensure that the target fish can rest while preventing small fish from getting lost and delaying their upstreaming time.

[0249] Fishway overall model test: The fishway overall model test mainly focuses on the vertical slot fishway23 to conduct the following research: a. The water flow pattern and fish entry and exit conditions at the designed fishway inlet and outlet under typical operating water levels upstream and downstream of the fishway; b. The flow rate, water surface along the designed fishway, flow velocity changes, and flow velocity patterns of the fish pond and rest pool36 under different operating water levels during the fishing season; c. Propose suggestions for optimizing the type, scale, and plane layout of the fishway inlet and outlet.

[0250] Design and Production of the Overall Fishway Model: Similarity Conditions: The overall fishway model was designed as a normal model, following the gravity similarity criterion. Taking into account the structural dimensions of the fishway and the site constraints, the geometric scale of the overall fishway model was determined to be 1:15. The model should meet geometric similarity, water flow similarity, and dynamic similarity. The scales for each are shown in Table 15.

[0251] Table 15 Calculation table of scales of the overall fishway model

[0252] scale Plane scale Vertical scale Flow rate scale Flow rate scale Roughness scale formula <![CDATA[λ L ]]> <![CDATA[λ H ]]> <![CDATA[λ v =λ L 1 / 2 ]]> <![CDATA[λ Q =λ L 5 / 2 ]]> <![CDATA[λ n =λ L 1 / 6 ]]> Actual scale 15 15 3.87 871 1.57

[0253] The model water flow is turbulent, and the model Reynolds number Re m =5230>1000, V: water flow velocity; R: hydraulic radius; ν: water flow viscosity coefficient.

[0254] Model making: The overall model making of the fishway is based on the hub plan layout, plant operation layer plan layout, plant section, project area topography, fishway plan layout and the pool chamber 30 structure diagram after optimization of the cross-section model provided by the design unit. In combination with the design requirements and test content, the model simulates the original river section length of about 450m, of which 200m is upstream of the dam axis and 250m is below the dam axis. It simulates two units, the fishway inlet, the entire trough body and the outlet, etc. The model is 30m long and 5.5m wide. In order to ensure that the natural terrain can be accurately reproduced on the model and to ensure the accuracy of model making, the plane survey adopts the plane wire control system, and the plane position error is controlled within ±5mm; the terrain production adopts the cross-section method, and the average cross-section spacing is about 90cm, which is basically perpendicular to the main river channel, and the terrain elevation error is within ±0.5mm. The fishway trough body and partition 32 are made of plastic plates. Model layout see Figure 23 .

[0255] Design scheme test study: Overall model design scheme of fishway Design scheme overview: Plane layout: The fishway is arranged on the left side of the power station 27, and the inlet is arranged about 30m downstream of the power station 27, using the tail water of the power station 27 to attract fish. After passing through the inlet, the fishway meanders upstream, with an axis length of about 485m, during which 120 pool chambers 30 and 4 rest pools 36 are arranged. The rest pools 36 are arranged at 3 bends and the fishway flood gates. Each rest pool 36 is 6.6m long. The outlet is arranged about 150m upstream of the dam. The overall layout of the fishway is shown in Figure 23 The plane structure of chamber 30: In the overall model design scheme test, the structural dimensions of chamber 30 were optimized using the cross-section model, i.e., the net width of chamber 30 is 3.0m, the length is 3.6m, the partition 32 is 1.83m long, the guide plate 35 is 0.95m long, the vertical seam 31 is 0.45m wide, the diversion angle is 45°, and the bottom slope of chamber 30 is 1:51.02. The plane structure dimensions of chamber 30 are shown in the table. Figure 24 , unit: cm. Test Conditions: As shown in Table 16, based on the designed operating water levels upstream and downstream of the fishway, the model selected six typical operating conditions for testing: the upstream maximum and minimum operating water levels, the downstream minimum operating water level (fishway inlet depth of 1.0 m), an inlet depth of 1.7 m (identical to the outlet depth at the upstream maximum water level), and the maximum operating water level (fishway inlet depth of 3.36 m). The test conditions are shown in Table 17.

[0256] Table 16 Fishway design operating water level

[0257] Design operating water level Maximum water level (m) Minimum water level (m) Water level fluctuation (m) upstream 8.7 8 0.7 downstream 1.84 -0.52 2.36

[0258] Table 17 Model test conditions

[0259]

[0260] Analysis of test results: Water level along the fishway: The changes of water level along the fishway under various working conditions are shown in Figure 25 To facilitate the analysis of the hydraulic characteristics along the fishway, the four rest pools set up in the fishway are numbered from 1# to 4# from the downstream fishway entrance to the upstream fishway entrance.

[0261] Condition 1: The normal water level of the upstream reservoir is 8.7 m (the maximum operating level upstream of the fishway), and the water level below the dam (the fishway inlet) is -0.52 m from the fishway's designed minimum operating level. The water depth at the fishway outlet is 1.7 m, and the water depth at the inlet is 1.0 m. From the water surface along the entire length of the resting pool, the water depth in chambers 30 above 2# resting pool 36 is approximately 1.7 m, and the water level difference between adjacent chambers 30 is roughly consistent, at around 0.07 m, consistent with the design value. Chambers 30 below 2# resting pool 36 are significantly affected by the downstream water level, with water depth decreasing along the length of the resting pool. The water level difference between chambers 30 gradually increases, reaching an average of 0.13 m for the seven most downstream chambers 30. Condition 2: The normal water level of the upstream reservoir is 8.7 m (the maximum operating level upstream of the fishway), and the water level below the dam (the fishway inlet) is 0.18 m. Under this operating condition, the water depth at both the inlet and outlet of the fishway is 1.7m. The water surface in each of the 30 chambers along the fishway fluctuates slightly, with the water surface gradient roughly consistent with the bottom slope of the fishway. The water depth within each chamber is approximately 1.7m, and the water level difference between the chambers is approximately 0.07m, consistent with the design value. Operating Condition 3: The normal water level of the upstream reservoir is 8.7m (the maximum operating level upstream of the fishway), and the water level below the dam is 1.84m (the maximum operating level downstream of the fishway). The water depth at the fishway outlet is 1.7m, and the water depth at the inlet is 3.36m. Looking at the water surface profile along the length of the 30 chambers upstream of the 3# resting pool 36, the water depth is approximately 1.7m, and the water level difference between the 30 chambers is approximately 0.07m. Downstream of the 3# resting pool 36, the water surface gradient decreases, and the water depth and the drop between the chambers gradually decrease. The average drop between the 7 chambers 30 downstream is only 0.02m. Condition 4: The upstream reservoir is at a dead water level of 8.0m (the fishway's upstream minimum operating level), and the water level below the dam (the fishway inlet) is -0.52m from the fishway's designed minimum operating level. Under this condition, the water depth at both the inlet and outlet of the fishway is 1.0m. The water surface profile along the fishway fluctuates little, and the water surface gradient is generally consistent with the fishway bottom slope. The water depth within each chamber 30 is approximately 1.0m, and the water level difference between the chambers is approximately 0.07m, consistent with the design value. Condition 5: The upstream reservoir is at a dead water level of 8.0 m (the lowest operating water level upstream of the fishway), and the water level below the dam (at the fishway inlet) is 0.18 m. The water depth at the fishway outlet is 1.0 m, and the inlet is 1.7 m. From the water surface profile, the water depth of each chamber upstream of the 3# resting pool 36 is approximately 1.0 m, and the water level difference between the 30 chambers is approximately 0.07 m. Downstream of the 3# resting pool 36, the water surface gradient decreases along the entire length of the chambers, affected by the downstream water level. The water depth of each chamber 30 gradually decreases, and the height difference between the 30 chambers 30 gradually decreases, reaching an average height difference of only 0.03 m for the 7 most downstream chambers 30. Condition 6: The upstream reservoir is at a dead water level of 8.0 m (the lowest operating water level upstream of the fishway), and the water level below the dam is 1.84 m (the highest operating water level downstream of the fishway). The water depth at the fishway outlet is 1.0 m, and the inlet is 3.36 m.Judging from the water surface line along the process, the water depth of each chamber upstream of the 4# rest pool 36 is about 1.0m, and the water level difference among the 30 chambers is about 0.07m; the chambers 30 downstream of the 4# rest pool 36 are affected by the downstream water level, and the water surface line gradient along the process decreases, the water depth of each chamber 30 gradually decreases, and the height difference among the 30 chambers gradually decreases. The average height difference among the 7 chambers 30 downstream is only 0.006m.

[0262] Flow velocity and flow pattern in the fishway: 1. Flow velocity in vertical slit 31: The flow velocity changes along the vertical slit 31 in the fishway under different working conditions are shown in the figure. Figure 26 . Among them, the 124 vertical slits 31 set in the fishway are numbered as 1# vertical slit 31 to 124# vertical slit 31 in the direction from the downstream fishway entrance to the upstream fishway exit. Working condition 1: The flow velocity of each vertical slit 31 upstream of the 2# rest pool 36 does not change much, and is all around 0.96m / s. The flow velocity of each vertical slit 311-32# downstream of the 2# rest pool 36 gradually increases due to the decrease in water depth and the increase in the height difference between the pool chambers 30. The flow velocities of the 1-15# vertical slits 31 all exceed the design flow velocity requirement of 1.0m / s, among which the flow velocity of the 1# vertical slit 31 reaches 1.66m / s. Working condition 2: The flow velocity of each vertical slit 31 along the fishway does not change much, and is all between 0.93-0.98m / s, meeting the design flow velocity requirement. Working condition 3: The flow velocity of each vertical slit 31 upstream of the 3# rest pool 36 does not change much, and is all around 0.96m / s. The flow velocity of each vertical slit 311-48# downstream of 3# rest pool 36 is gradually reduced due to the increase in water depth and the decrease in the height difference between 30 pool chambers, among which the flow velocity of 1# vertical slit 31 is 0.48m / s. Under this working condition, the flow velocity of each vertical slit 31 along the process meets the design requirements. Working condition 4: The flow velocity of each vertical slit 31 along the fishway does not change much, and is all between 0.93-0.98m / s, which meets the design flow velocity requirements. Working condition 5: The flow velocity of each vertical slit 31 upstream of 3# rest pool 36 does not change much, and is all around 0.96m / s. The flow velocity of each vertical slit 311-48# downstream of 3# rest pool 36 is gradually reduced due to the increase in water depth and the decrease in the height difference between 30 pool chambers, among which the flow velocity of 1# vertical slit 31 is 0.55m / s. Under this working condition, the flow velocity of each vertical slit 31 along the process meets the design requirements. Condition 6: The flow velocity in each vertical slit 31 upstream of the 3# rest tank 36 remained relatively constant at approximately 0.96 m / s. Downstream of the 3# rest tank 36, the flow velocity in each vertical slit 311-48 gradually decreased due to the increased water depth and the reduced height difference between the chambers 30. Compared to Condition 5, the flow velocity in each vertical slit 31 decreased significantly due to the significant increase in the inlet water depth, with the flow velocity in the 1# vertical slit 31 reaching 0.29 m / s. Under this condition, the flow velocity in each vertical slit 31 along the entire length met the design requirements.

[0263] Flow rate and flow pattern of chamber 30: Figure 27As shown in the figure, the flow patterns of the water in each fish pond of the fishway under each working condition are basically the same. Generally speaking, there are two different flow patterns in the pond chamber 30, namely the mainstream area connecting the two-level vertical slits 31 and the recirculation area forming a closed streamline. After the water flows out of the vertical slit 31, it is deflected toward the center of the fish pond under the action of the guide plate 35. When it approaches the next vertical slit 31, it is deflected toward the vertical slit 31 under the action of the guide plate 35, and the mainstream presents a significant S-shaped streamline. There is a relatively symmetrical recirculation area on each side of the mainstream, with the recirculation on the left side in a counterclockwise direction and the recirculation on the right side in a clockwise direction. The above water flow patterns are consistent with the results of the fishway cross-section model test.

[0264] Under each working condition, the changes in the mainstream flow velocity in each fish pond along the process are shown in Figure 28 In this experiment, the 120 fish ponds in the fishway were numbered 1# to 120# chambers 30 from the downstream fishway entrance to the upstream fishway exit. The test results show that in working conditions 2 and 4, since the water depth of each chamber 30 along the way is consistent, the flow velocity in the chamber 30 does not change much, mostly between 0.72-0.78m / s; in working condition 1, since the inlet water depth is lower than the outlet water depth, the flow velocity gradually increases from 30# chamber 30 to 1# chamber 30, among which the mainstream flow velocity of 1# chamber 30 is 1.31m / s; in working conditions 3, 5 and 6, since the inlet water depth is lower than the outlet water depth, the mainstream flow velocity of each downstream chamber 30 shows a gradually decreasing trend. Among them, in working condition 3, the mainstream flow velocity of 46# to 120# chambers 30 is mostly between 0.72-0.78m / s, and the flow velocity gradually decreases from 0.71m / s to 0.4m / s from 45# chamber 30 to 1# chamber 30. In working condition 5, the mainstream flow velocity in pools 30# to 120# was mostly 0.72-0.78 m / s. From pool 30# to pool 30#, the flow velocity gradually decreased from 0.70 m / s to 0.46 m / s. In working condition 6, the mainstream flow velocity in pools 30# to 52# was mostly 0.72-0.78 m / s. From pool 30# to pool 30#, the flow velocity gradually decreased from 0.70 m / s to 0.25 m / s.

[0265] Flow velocity and flow pattern in rest pool 36: Figure 29 As shown, this fishway project has a total of 4 rest pools 36, of which the 4# rest pool 36 is arranged in the straight section, and the 1-3# rest pools 36 are arranged in the turning section. Compared with the pool chamber 30, the flow pattern of the water in the rest pool 36 has changed significantly. Among them, since the longitudinal distance between the baffles 32 at both ends of the 4# rest pool 36 is longer, the water is basically not affected by the downstream baffle 32 after flowing out of the upstream vertical seam 31 and directly hits the left side wall, and then moves close to the side wall. After reaching the end of the rest pool 36, it is affected by the downstream baffle 32 and turns to the vertical seam 31; Figure 30 As shown in a, the 3# rest pool 36 is located downstream of the observation room. Since the fish passage at the observation room 34 is located on the left, the main flow of the corresponding rest pool 36 is close to the left wall of the arc, with a width of about 0.7m, and a large-scale recirculation area inside; Figure 30As shown in b, the flow patterns of 1# and 2# rest pools 36 are consistent, with the mainstream located inside the turning section with a width of about 0.7m, and a large-scale recirculation area outside; Figure 30 As shown in Figure a, the width of the fish passageway outside the observation room 34 is 1.0 m, and the water flow is straight. Table 18 shows the mainstream flow velocities within each resting pool 36 and the fish passageway of the observation room 34 under various operating conditions. As can be seen from the table, under operating conditions 1 and 2, the maximum flow velocities within each resting pool 36 were not significantly different, ranging from 0.54 to 0.69 m / s. Under operating condition 3, due to the increased inlet water depth, the maximum flow velocity in resting pool 1 36 decreased slightly to 0.41 m / s, while the maximum flow velocities in the other resting pools 36 were around 0.55 m / s. Under operating conditions 4 and 5, the maximum flow velocities within each resting pool 36 were not significantly different, ranging from 0.53 to 0.65 m / s. Under operating condition 6, due to the increased inlet water depth and the reduced flow from the fishway body, the maximum flow velocity in resting pool 1 36 was significantly lower than that under other operating conditions, reaching only 0.27 m / s. However, this was still greater than the induced flow velocity of the fish and did not pose a barrier to their upstream movement. The flow rate of the fish passage in the observation room under each working condition is between 0.36 and 0.44 m / s, which meets the requirements for fish to migrate upstream.

[0266] Table 18 Flow rate of the rest pool 36 and the fish passage of the observation room 34 m / s

[0267] Test conditions 1 2 3 4 5 6 1# Rest Pool 36 0.69 0.65 0.41 0.65 0.54 0.27 2# Rest Pool 36 0.67 0.66 0.54 0.65 0.64 0.39 3# Rest Pool 36 0.61 0.6 0.55 0.6 0.59 0.49 4# Rest Pool 36 0.56 0.54 0.54 0.55 0.53 0.55 Observation Room 34 0.44 0.43 0.39 0.41 0.42 0.36

[0268] Fishway inlet and outlet flow rate and flow pattern: Fishway inlet: The fishway inlet is the main entrance for migratory fish to enter the fishway and is the most important component of the fishway. The fishway inlet of this project is located about 30m downstream of the power station 27, and the fish are attracted by the tail water of the power station 27. Figure 30 c and Figure 32 As shown in the figure, the flow patterns at the inlet of the fishway under various working conditions are not much different. Affected by the jet flow of the last vertical slit 31, the inlet presents a staggered distribution of mainstream and return flow. The mainstream passes the inlet turning point close to the right side wall, and the mainstream width is about 1.0m. The inlet mainstream flow velocity gradually decreases with the increase of downstream water level. The inlet mainstream flow velocity of working condition 1 is the largest, which is 0.69m / s. The inlet mainstream flow velocity of working condition 6 is the smallest, which is 0.15m / s, which is lower than the induced flow velocity of migratory fish and does not meet the design requirements. The mainstream flow velocity of the fishway inlet under various working conditions is shown in Table 19. Figure 32 As shown in Figure a, under various operating conditions of the fishway, the flow field characteristics of the river channel near the inlet are basically the same, the flow velocity distribution is relatively uniform, the water flow is smooth, and the water flow velocity is between 0.25 and 0.4 m / s, which is between the induced flow velocity and the critical swimming speed of the fish passing through, and can achieve a good fish attracting effect.

[0269] Table 19 Mainstream flow velocity at the fishway inlet

[0270] Test conditions 1 2 3 4 5 6 Reservoir water level m 8.7 8.7 8.7 8 8 8 Water level below dam (m) -0.52 0.18 1.84 -0.52 0.18 1.84 Inlet mainstream flow rate m / s 0.69 0.4 0.21 0.38 0.26 0.15

[0271] Fishway exit: Figure 32 As shown in Figure b, the fishway outlet is located on the left bank, about 150 m upstream of the dam. Observations based on the overall model of the hub show that the water flow near the fishway outlet is smooth. Affected by the deep water depth of the reservoir, the flow velocity is mostly between 0.03 and 0.1 m / s, which basically meets the design requirements.

[0272] Summary of the design scheme: Under the engineering layout conditions of the design scheme, the water depth of the 30m chamber in the upstream section of the fishway is mainly affected by the water level of the reservoir, and the water depth of each 30m chamber is basically consistent with the water depth of the fishway outlet; the water depth of the 30m chamber in the downstream section of the fishway is significantly affected by the change of the downstream water level, and the water depth fluctuates greatly; under all working conditions, the water depth of each 30m chamber along the way meets the design requirement of not less than 1.0m; the flow rate of the fishway is mainly controlled by the water level of the upstream reservoir and is basically not affected by the change of the downstream water level. Under the working condition of the reservoir water level of 8.7m, the flow rate of the fishway is 0.74m 3 / s, when the reservoir water level is 8.0m, the fishway flow rate is 0.44m 3 / s; under the working conditions of 8.0m reservoir water level, the flow velocity of each vertical seam 31 along the process meets the requirements; when the reservoir water level is 8.7m, when the downstream water level is lower than 0.18m, the flow velocity of the vertical seam 311-15# vertical seam 31 below 1# rest pool 36 exceeds the design flow velocity requirement; under working conditions 2 and 4, the mainstream flow velocity of each pool chamber 30 along the process does not change much, mostly in the range of 0.72-0.78m / s; under working condition 1, the flow velocity gradually increases from 30# pool chamber 30 to 1# pool chamber 30, and the maximum flow velocity of 1# pool chamber 30 is 1.31m / s; under working conditions 3, 5 and 6, the mainstream flow velocity of each pool chamber 30 downstream shows a trend of gradually decreasing. In Condition 6, the flow rate in Chamber 1# 30 was the lowest, at 0.25 m / s. The mainstream flow rate at the fishway inlet gradually decreased as the downstream water level rose, reaching only 0.15 m / s in Condition 6, falling short of the design requirements. The flow rates at the fishway inlets in the remaining conditions ranged from 0.21 to 0.69 m / s. The river flow near the inlet was smooth, with velocities between 0.25 and 0.4 m / s, falling between the induced velocity and critical swimming speed of the fish, effectively attracting them. The flow at the fishway outlet was also smooth, with velocities mostly within 0.1 m / s, meeting the design requirements.

[0273] Experimental Study of Optimization Schemes: Optimization Strategies: Experimental verification of the fishway design revealed two issues: First, when the reservoir water level was 8.7 m and the downstream water level was below 0.18 m, the flow velocity in the downstreammost straight section of the chambers 30 and vertical slits 31 exceeded the design requirements. Second, when the reservoir water level was 8.0 m and the downstream water level was 1.84 m, the flow velocity at the fishway inlet was too low, falling below the fish-sensed velocity. The main reason for the flow velocity exceeding the design requirements in the vertical slits 31 within the fishway trough and within the fish pond was that the fishway design parameters failed to fully adapt to water level fluctuations at the inlet. As a continuous water-passing structure, the fishway trough, while maintaining consistent flow across all chambers 30, significantly increases the flow velocity in the lower chambers 30. Based on this analysis, the proposed optimization strategies are: first, reducing the flow rate in the fishway trough to match the water depth of the lower chambers 30 under low water level conditions; and second, increasing the water depth of the chambers 30 with excessive flow velocity to reduce the flow velocity. As for the problem of fishway import, the main consideration is to solve it by importing water.

[0274] Optimization Plan 1: Optimization Engineering Measures: Optimization Plan 1 intends to reduce the fishway flow rate by reducing the width of the vertical slits 31 of some chambers 30 at the upstream outlet section of the fishway, thereby reducing the flow rate of the vertical slits 31 of the chambers 30 near the inlet. The specific measures are: reduce the width of the vertical slits 31 of the 30 most upstream chambers 30. To avoid adverse flow conditions caused by sudden changes in the width of the vertical slits 31, adjust the width of the vertical slits 31 of the 10 most upstream chambers 30 to 0.3m, the width of the vertical slits 31 of the subsequent 10 chambers 30 to 0.35m, and the width of the vertical slits 31 of the next 10 chambers 30 to 0.4m. See the layout of the optimization plan. Figure 33 . Analysis of test results: The optimization scheme was tested under two typical working conditions: working condition 1 (high water level upstream and low water level downstream) and working condition 4 (low water level upstream and downstream). The test results show that due to the reduction in the width of the vertical slit 31 in the outlet section, the flow rate of the fishway is effectively reduced. Under working condition 1, the flow rate of the fishway is reduced from 0.74m3 / s in the design scheme to 0.53m3 / s. Correspondingly, the flow velocities of each chamber 30 and vertical slit 31 near the fishway inlet are reduced, but the flow rate of the most downstream vertical slit 31 (1# vertical slit 31) still exceeds the design requirements, which is 1.21m / s. Comparison of the flow rate of vertical slit 31 in the optimization scheme 1 and the design scheme for working condition 1 is shown in Figure 34 In addition, the test found that under working condition 4 (design minimum water level), due to the reduction of the flow rate of the fishway, the water depth of most of the pool chambers 30 in the middle and lower part was less than the design scheme, with the minimum water depth being 0.78m, which did not meet the design minimum water depth requirement. Figure 35 .

[0275] Optimization Plan 2: Optimization measures: It is proposed to increase the water depth of the chamber 30 by lowering the bottom elevation of the 15 chambers 30 (1-15#) and the inlet in the most downstream straight section, thereby reducing the flow velocity in the vertical slot 31. Specific measures include: lowering the bottom elevation of the fishway inlet from -1.52m to -2.22m, and adjusting the bottom slope of the chamber 30 in the most downstream straight section from 1.95% to 3.24%. The optimization plan layout is shown in Figure 36 . Analysis of test results: The optimization scheme was tested under the six working conditions listed in Table 17. The test results show that the water surface line and flow rate along the fishway under each working condition of the optimization scheme 2 are basically consistent with the design scheme. The water depth of each chamber 30 in the most downstream straight section increases significantly due to the decrease in the bottom elevation, and the flow rate of each chamber 30 and the vertical seam 31 decreases significantly. Under working condition 1, the flow rate of the 1# vertical seam 31 decreases from 1.66m / s to 0.98m / s, and the mainstream flow rate of the 1# chamber 30 decreases from 1.31m / s to 0.76m / s. The maximum flow rate of the vertical seam 31 and the chamber 30 occurs at the place where the bottom slope changes, that is, the 16# vertical seam 31 and the 15# chamber 30, with flow rates of 1.08m / s and 0.79m / s respectively. The minimum flow rate of vertical seam 31 and pool chamber 30 occurs in working condition 6, with flow rates of 0.25m / s and 0.21m / s, respectively, which basically meet the design requirements. Figure 37 、 Figure 38 and Figure 39 .

[0276] The flow pattern of the water flow at the fishway inlet under each working condition of the optimization scheme does not change much from the design scheme. Due to the decrease in the inlet bottom elevation and the increase in water depth, the corresponding inlet flow rate decreases. The comparison of the mainstream flow rate at the fishway inlet under each working condition and the design scheme is shown in Table 20. It can be seen from the table that the flow rate at the fishway inlet in working condition 1 is the largest, which is 0.4m / s. The flow rate at the fishway inlet in working condition 6 is the smallest, which is 0.11m / s. Under working conditions 3 and 6, that is, the highest downstream operating water level conditions, the inlet flow rate is lower than the migratory fish induced flow rate (0.2m / s), which does not meet the design requirements. In this regard, the model conducted a water replenishment test for the above two working conditions. The test shows that in order to ensure that the mainstream flow rate at the fishway inlet is not lower than the migratory fish induced flow rate, the minimum water replenishment flow rate for working conditions 3 and 6 is 0.7m / s respectively. 3 / s、1.0m 3 / s. The inlet flow pattern before and after water replenishment is shown in Figure 40 .

[0277] Table 20 Main flow velocity at the fishway inlet and water replenishment flow rate under various working conditions

[0278] Operating conditions 1 2 3 4 5 6 Design inlet flow rate m / s 0.69 0.4 0.21 0.38 0.26 0.15 Optimization solution 2 inlet flow rate m / s 0.42 0.27 0.17 0.25 0.2 0.11 <![CDATA[Makeup water flow rate m 3 / s]]> -- -- 0.7 -- -- 1

[0279] Summary of optimization scheme: In response to the problems existing in the design scheme, two optimization schemes were tested based on the two ideas of reducing the flow rate of the fishway body and increasing the water depth of the chamber 30 where the flow rate exceeds the standard. Optimization scheme 1 takes the measure of reducing the width of the vertical slit 31 in the outlet section, which achieves the purpose of reducing the flow rate of the fishway, so that the flow rate of each chamber 30 and vertical slit 31 in the most downstream straight section is reduced, but still does not meet the design flow rate requirement. In addition, the reduction in the flow rate of the fishway caused a significant drop in the water level of most of the middle chambers 30. Under working condition 4, the water depth of the chamber 30 does not meet the minimum design water depth requirement of the fishway. Optimization scheme 2 increases the water depth of the chamber 30 and effectively reduces the flow rate of the vertical slit 31 by reducing the elevation of 15 chambers 30 [1-15#] and the inlet bottom in the most downstream straight section. Under all working conditions, the flow rates of the fishway vertical slits 31 and the pool chamber 30 can meet the design requirements. However, the lowering of the bottom elevation of the fishway inlet and the increase in water depth significantly reduce the inlet flow rate. In working conditions 3 and 6, i.e., the highest downstream operating water level working conditions, the inlet flow rate is 0.2m / s lower than the induced flow rate of migratory fish, which does not meet the design requirements. In order to ensure that the mainstream flow rate of the fishway inlet is not lower than the induced flow rate of migratory fish, water needs to be replenished at the fishway inlet. The minimum replenishment flow rate for working conditions 3 and 6 is 0.7m / s respectively. 3 / s、1.0m 3 / s.

[0280] In summary, by establishing a 1:25 scale overall fishway model and combining the results of local model tests, the layout of the vertical slot fishway 23 in Hub 1 was demonstrated and optimized experimentally. The following conclusions were drawn:

[0281] According to the design plan, the flow rate of the fishway is mainly controlled by the water level of the upstream reservoir and is basically not affected by changes in the downstream water level. Under the working condition of reservoir water level of 8.7m, the flow rate of fishway is 0.74m3 / s; under the working condition of reservoir water level of 8.0m, the flow rate of fishway is 0.44m3 / s; under all working conditions, the water depth of each chamber 30 along the process meets the design requirement of not less than 1.0m; when the reservoir water level is 8.7m, when the downstream water level is lower than 0.18m, the flow velocity of vertical seam 31 and chamber 30 near the fishway inlet below 1# rest pool 36 exceeds the design requirement, the maximum flow velocity of vertical seam 31 is 1.66m / s, and the maximum flow velocity of chamber 30 is 1.31m / s; the flow velocity of fishway inlet gradually decreases with the increase of downstream water level. The mainstream flow velocity of inlet in working condition 6 is only 0.15m / s, which does not meet the design requirement. The flow velocity of fishway inlet in other working conditions is between 0.21-0.69m / s; the water flow at the fishway outlet is smooth, and the flow velocity is mostly within 0.1m / s. The water flow is relatively smooth, meeting the design requirements.

[0282] In response to the problem of excessive flow rate in the vertical seam 31 and the pool in the lower section of the fishway in the design scheme, optimization measures were proposed to lower the bottom elevation of the fishway inlet [from -1.52m to -2.22m] and increase the slope of the most downstream straight section chamber 30 [from 1.95% to 3.24%]. By increasing the water depth of chamber 30, the purpose of reducing the flow rate was achieved to meet the requirements; under the operating conditions of working conditions 3 and 6 [high water level downstream], the flow rate at the fishway inlet was lower than the induced flow rate of migratory fish [0.2m / s], which did not meet the design requirements and required water replenishment at the fishway inlet. The minimum water replenishment flow rates for working conditions 3 and 6 were 0.7m3 / s and 1.0m3 / s, respectively.

[0283] Conclusions and suggestions: The model test research project of the fishway project at the hub uses a variety of technical means such as data analysis, on-site testing, and physical model testing to carry out four parts of research content: 1. Research on the swimming ability of the target fish species passing through the fishway to clarify the migratory ecological characteristics of the fish passing through; 2. Design of the fishway 2 scheme, and propose a preliminary design scheme for the fishway plane and the structure layout of chamber 30; 3. Physical model test of the local section of the fishway project, based on the preliminary design scheme, carry out the demonstration and optimization research on the structure layout of chamber 30 of the vertical slot fishway 23, and propose a recommended scheme for the structure of chamber 30; 4. Overall model test research of the fishway, based on the preliminary design scheme and the recommended scheme for the structure of chamber 30, carry out the overall hydraulic characteristics test research of the vertical slot fishway 23, and propose a recommended scheme for the overall layout of the fishway and operation suggestions. The specific conclusions are as follows:

[0284] Study on the Swimming Ability of Target Fish Passages: Analysis and review of existing data indicate that the primary purpose of the Hub 1 fishway is to connect river-sea migratory fishes, providing upstream migration for estuarine fishes and a migratory pathway and genetic exchange for freshwater fishes. The primary fish passing through the Hub 1 fishway should be catadromous fishes [CA] and anadromous fishes [AN]. After review, the primary catadromous fishes [CA] are: flower eel, eel, and sea bass; and anadromous fishes [AN] are: seven-thread anchovy and flower shad. Also considered are: spotted shad, Chinese snakehead, spotted tongue goby, silverfish, tongue goby, semi-ridged Chinese fish, and other estuarine fishes, as well as Hepu mitten crabs. The fishing season is November to September. The vertical slot fishway 23 primarily serves fish with a diameter of 40 to 600 mm, while the eel channel 24 serves fish with a diameter of 100 to 500 mm. The design parameters for the first fishway were determined by conducting swimming tests on the main fish species of the hub, including sea bass, eel, red-eyed trout, and dace, as well as the fish currently distributed in this section of the river. The flow velocity through the holes / slits of the vertical slot fishway 23 should range from 0.54 to 1.37 m / s, with an average flow velocity of approximately 1.0 m / s. The average flow velocity in chamber 30 should range from 0.24 to 0.67 m / s. The inlet flow velocity should not be lower than the fish-sensing velocity by 0.2 m / s, and should preferably be between 0.35 and 0.73 m / s. The outlet flow velocity should not be still water, and should preferably be between 0.24 and 0.35 m / s. Eels are fish with climbing habits. Although their measured swimming ability is relatively small, the eel track 24 should not be designed simply based on the measured swimming ability. The eel track 24 can be designed as a steeper slope, but staggered cylindrical tubes or piers should be designed at the bottom to provide a foothold for their climbing.

[0285] Fishway 2 design: Taking into account the migratory behavior characteristics of the fish passing through Hub 1 and the water scheduling plan for the Hub 1 fishway, a dual fishway design was adopted: vertical slot fishway 23 and eelway 24. Both vertical slot fishway 23 and eelway 24 were located on the left bank, close to the shore of the tailwater of power station 27. Eelway 24 and vertical slot fishway 23 met near the downstream observation room 34 and then merged into vertical slot fishway 23. The vertical slot fishway 23 was designed with a bottom slope of 1:51.02, a total length of 458 meters, and one inlet with a bottom elevation of -1.52 meters and one outlet with a bottom elevation of 7 meters. The fishway includes 30,120 chambers and 364 rest pools. The cross-section of the chamber 30 is rectangular, the bottom slope of the chamber 30 is I = 1.96%, the thickness of the partition 32 and the guide plate 35 are both 30 cm, the diversion angle is 30°, no pier heads are set at the ends of the partition 32 and the guide plate 35, and the ends are rounded with a radius R = 15 cm; the net width of the chamber 30 is 3.0 m, the length of the chamber 30 is 3.6 m, the design water depth h is 1.0 ~ 3.36 m, the design vertical seam 31 is 45 cm wide, and a pile structure 22 with a diameter of 15 cm and a height of 10 cm is set at the bottom. The centerline spacing of the piles is 45 cm, and they are arranged in two rows in a staggered manner. The design of Eelway 24 is as follows: at the intersection of the left bank vertical retaining wall and the downstream bank, a vertical eelway entrance 24 is set towards the bank. Starting from the riverbed at -7.5m, an entrance is set every 1m, with a total of 7 eel entrances 33. The main channel is an aluminum water trough 13m long, 0.37m wide, and 0.1m high. The water trough has a slope of 15° and is covered with a lid. The water trough is equipped with a plastic climbing matrix 20. The matrix consists of staggered plastic tubes. The water trough tubes are immersed in water at a depth of more than 3cm. Eelway 24 merges into the vertical slot fishway 23 at an elevation of 3.39m. The eels will then use this vertical slot fishway 23 to continue upstream. An observation room 34 is provided on the upstream side of the intersection of the vertical slot fishway 23 and the eel way 24 to count the species and number of fish that have successfully gone upstream and to evaluate the fish passage effect of the fishway so as to improve the structure of the fishway and the fish passage effect in the future. It also serves as a publicity and demonstration function.

[0286] Physical model test of a local section of the fishway project: Based on the preliminary design of the vertical slot fishway 23, a local section model of the fishway with a geometric scale of 1:4 was established. The test found that the design scheme's pool chamber 30 scale, vertical slot 31 width, and main body bottom slope design were basically reasonable, meeting the target fish species' upstream migration requirements; the fishway flow rate was approximately 0.50 m3 / s, and the baffle 32 velocity coefficient φ = 0.97; the diversion angle was small, resulting in the average flow velocity of the vertical slot 31 (1.11 m / s) exceeding the design requirement, and there was no obvious deflection of the mainstream in the pool chamber 30, resulting in unfavorable water flow conditions in the pool chamber 30. Aiming at the problem that the diversion angle is too small, resulting in the water flow conditions in the vertical seam 31 and the pool chamber 30 not meeting the requirements of fish upstream migration, the diversion angle is adjusted to optimize the water flow structure of the pool chamber 30, with the idea of ​​promoting the deflection of the mainstream in the pool chamber 30 and increasing the energy dissipation of the mainstream. By comparing the water flow conditions of the pool chamber 30 and the vertical seam 31 of the three groups of optimization schemes, it is proposed to keep the scale of the pool chamber 30, the width of the vertical seam 31 and the bottom slope of the pool chamber 30 unchanged, and increase the diversion angle to 45°. The scheme adopts the method of the invention. Under the scheme, the average water level difference of the pool chamber 30 is 0.07m, the average flow velocity of the vertical seam 31 is 1.01m / s, the flow velocity distribution of the vertical seam 31 is between 0.99 and 1.06m / s, the flow velocity of the vertical seam 31 passing fish meets the average flow velocity of 1m / s, the flow velocity distribution range of 0.54 to 1.37m / s, the flow velocity coefficient φ=0.86, corresponding to the design water depth of 1m, the flow rate of the vertical seam 31 is about 0.45m3 / s, which is about 7% less than the design scheme.

[0287] Fishway overall model test: Based on the recommended structural scheme of chamber 30 and the preliminary design scheme of vertical slit fishway 23, a fishway overall model with a geometric scale of 1:15 was established. The study showed that the flow rate of the fishway is mainly controlled by the water level of the upstream reservoir and is basically not affected by the change of the downstream water level. Under the working condition of the reservoir water level of 8.7m, the flow rate of the fishway is 0.74m3 / s; under the working condition of the reservoir water level of 8.0m, the flow rate of the fishway is 0.44m3 / s; under each working condition, the water depth of each chamber 30 along the way meets the design requirement of not less than 1.0m; when the reservoir water level is 8.7m, when the downstream water level is lower than 0.18m, the flow rate of the vertical slit 31 and chamber 30 in the lower section of the fishway [below 1# rest pool 36] exceeds the design requirement, and the vertical slit 31 The maximum flow rate is 1.66m / s, and the maximum flow rate in chamber 30 is 1.31m / s; the flow rate at the fishway inlet gradually decreases with the increase of downstream water level. The mainstream flow rate at the inlet of working condition 6 is only 0.15m / s, which does not meet the design requirements. The flow rate at the fishway inlet of other working conditions is 0.21-0.69m / s; the water flow at the fishway outlet is smooth, and the flow rate is mostly within 0.03-0.1m / s. The water flow is relatively smooth, meeting the design requirements. In response to the problem of excessive flow rate in the vertical seam 31 and the pool in the lower section of the fishway in the design scheme, optimization measures were proposed to lower the bottom elevation of the fishway inlet [from -1.52m to -2.22m] and increase the slope of the pool chamber 30 in the most downstream straight section [from 1.95% to 3.24%]. This achieved the purpose of reducing the flow rate in the vertical seam 31 and the pool chamber 30 to meet the requirements. Under the operating conditions 3 and 6 [the water level below the dam is higher than 0.18m] of the optimized scheme, the flow rate in the fishway inlet was lower than the induced flow rate of migratory fish [0.2m / s], which did not meet the design requirements and made it difficult to ensure the fish attracting effect of the fishway inlet. Water replenishment was required at the fishway inlet. Model tests showed that to ensure that the fishway inlet reached the induced flow rate of migratory fish, the minimum water replenishment flow rates for working conditions 3 and 6 were 0.7m3 / s and 1.0m3 / s, respectively. After communicating with the design unit, it was found that this project is restricted by water resources and the implementation of imported water replenishment measures is difficult. Based on this, it is recommended to install water propellers at the fishway inlet to meet the inlet fish attracting flow rate requirements.

[0288] In summary, the optimized overall layout structure and operation plan of the fishway are as follows: the structure of the canal fishway includes an eel way 24 and a vertical slot fishway 23. The migratory fish in the eel way 24 include eels and mitten crabs, and the migratory fish in the vertical slot fishway 23 include red-eyed trout and dace. The eel way 24 and the vertical slot fishway 23 are located on the same side of the canal. A climbing matrix 20 is provided in the eel way 2. One end of the eel way 2 is connected to the middle part of the vertical slot fishway 23, and the other end extends to the bottom of the canal. The part of the vertical slot fishway 23 located upstream of the eel way 2 is also provided with a climbing matrix 20. The eel way 2 and the part of the vertical slot fishway 23 located upstream of the eel way 2 together form a migratory channel.

[0289] A preferred solution is that the climbing matrix 20 includes a plurality of rows of pile structures 22 , wherein each row is provided with at least two pile structures 22 at intervals, and adjacent rows of pile structures 22 are staggered along the length direction of the eel way 24 or the vertical slot fishway 23 .

[0290] The structure of a canal fishway of the present application provides climbing assistance for eels by staggering the pile structures 22 and adjacent rows of pile structures 22 along the length direction of the eel way 24 or the vertical slit fishway 23. At the same time, the pile structure 22 does not have bristles compared to the bristle base, so there is no debris blockage and it is easy to clean. Moreover, the pile structure 22 can play a role in dissipating energy by friction resistance, water flow counteraction and diffusion along the way, thereby improving the flow state and reducing the flow rate of the vertical slit 31 passing through the fish. The pile structure 22 can be a cylindrical tube or a pier, and the staggered pipes or piers designed at the bottom provide a fulcrum for the eels to climb. The pipes are preferably cylindrical tubes or frustum tubes. Figure 30 As shown, further preferably, a through hole 21 is provided on the upstream side of the frustum tube; the upper edge of the frustum tube and the edge of the through hole 21 form an arc transition; the height of the frustum tube is greater than the bottom diameter of the tubular structure, and the top diameter of the frustum tube is smaller than the bottom diameter of the frustum tube. In one preferred embodiment, the bottom diameter of the pile structure 22 is greater than the top diameter of the pile structure 22.

[0291] A preferred solution is that the pile structure 22 includes a plurality of forward-disposed frustum piles, the lower portion of the frustum piles being connected to the bottom of the migratory channel, the top of the frustum piles being closed, and the height of the frustum piles being greater than the diameter of the bottom portion of the frustum piles.

[0292] A preferred solution is as follows: the pile structure 22 is a tubular structure, the lower portion of which is connected to the bottom of the migratory channel, the upper portion of which is open, and a through hole 21 is provided on the upstream side of the tubular structure; the upper edge of the tubular structure and the edge of the through hole 21 transition in a circular arc; the height of the tubular structure is greater than the diameter of the tubular structure bottom, and the diameter of the top of the tubular structure is smaller than the diameter of the tubular structure bottom. The inner wall of the tubular structure can also assist eels in climbing, and the through hole 21 is provided on the upstream side of the tubular structure, which can provide better migratory conditions for small fish such as Hepu mitten crabs and eels. At the same time, the tubular structure, in combination with the through hole 21, can better dissipate energy by friction along the way, counteracting water flow, and diffusing it, thereby better improving the flow pattern and reducing the flow velocity of the vertical slit 31 through which the fish pass. Preferably, the migratory channel includes a driving mechanism, a four-bar linkage, a base and a fishway bottom plate structure. The base and the fishway bottom plate structure are both inclined, and the pile structure 22 is arranged on the fishway bottom plate structure. The driving mechanism drives the four-bar linkage to drive the fishway bottom plate structure to slide back and forth with the base.

[0293] The eel channel 24 and the vertical slot fishway 23 are both arranged on the tailwater side of the power station 27 of the hub 1, which is the mainstream edge of the physical barrier [sluice] under most working conditions, and is more suitable for attracting and attracting fish.

[0294] This embodiment also discloses a fishway construction method for forming the canal fishway structure of the present application, comprising the following steps: S1: constructing a vertical slot fishway 23; S2: constructing an eelway 24 and connecting the eelway 24 to the vertical slot fishway 23; S3: adjusting the slope and diversion angle of the eelway 24. The fishway construction method of the present application, based on the canal fishway design method of this embodiment, first constructs the vertical slot fishway 23, then constructs the eelway 24, and finally adjusts the slope and diversion angle of the eelway 24, thereby constructing a more optimized canal fishway structure. The entire process is simple and cost-effective.

[0295] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for designing a canal fishway, characterized in that: The following steps are involved: S1: Establish a fishway database at the hub, evaluate the swimming ability of target fish species passing through the fishway, and determine the migratory ecological characteristics of the target fish species; S2: Based on the ecological characteristics of the migration of fish objects and the fishway database at the hub, a fishway scheme is designed to determine the preliminary design scheme of the fishway structure. The fishway (2) in the preliminary design scheme of the fishway structure includes an eel way (24) and a vertical slot fishway (23). The migratory fish in the eel way (24) include eels and Hepu mitten crabs, and the migratory fish in the vertical slot fishway (23) include red-eyed trout and dace. One end of the eel way (24) is connected to the middle of the vertical slot fishway (23), and the other end extends to the bottom of the canal; S3: Based on the preliminary design scheme of the fishway structure, a local cross-section physical model of the fishway project is designed, and a local cross-section physical model test of the fishway project is conducted to obtain a recommended scheme for the pool chamber structure located upstream of the eel channel (24) in the vertical slot fishway (23); S4: Build an overall fishway model based on the preliminary design and the recommended chamber structure, and conduct a fishway overall model test to determine the overall fishway structure. Wherein, the step S2 specifically includes the following steps: S21. Determine the design flow rate of the eel passage (24) and the design flow rate of the vertical slot fishway (23) based on the migratory ecological characteristics of the fish passage and the initial technical parameters of the fishway, wherein the design flow rate of the vertical slot fishway (23) includes the flow rate through the fish hole / slit, the inlet fish attracting flow rate, the outlet flow rate, and the main structure flow rate of the vertical slot fishway (23); S22. Based on the fishway database at the hub, the initial technical parameters of the fishway, the design flow velocity of the eelway (24), the design flow velocity of the vertical slot fishway (23), and the tailwater position of the power station (27) in the hub (1), determine the layout positions of the vertical slot fishway (23) and the eelway (24), as well as the position where the eelway (24) connects to the vertical slot fishway (23); S23: The design water level at the vertical slot fishway outlet (25) is determined based on the layout of the vertical slot fishway (23) and the eelway (24), the design water storage level of the hub (1), and the water level fluctuation parameters; and the design water level at the vertical slot fishway inlet (26) is determined based on the average low tide level of the tidal river section downstream of the hub (1), the water level fluctuation, and the cumulative frequency of low tides below the hub (1); S24: determining an angle parameter between the axis of the vertical slot fishway inlet (26) and the riverbed water flow and a width parameter of the vertical slot fishway inlet (26) based on a design water level at the vertical slot fishway outlet (25) and a design water level at the vertical slot fishway inlet (26); S25: determining the width of the vertical slot fishway (23) based on the width parameter of the vertical slot fishway inlet (26); S26: determining structural parameters of the vertical slot fishway (23) based on a design water level at the vertical slot fishway outlet (25), a design water level at the vertical slot fishway inlet (26), a size of a maximum fish-passing object in the fish-passing specification, and a width of the vertical slot fishway (23); S27: Based on the structural parameters of the vertical slot fishway (23), the structural position of the eelway and the arrangement parameters of the pile structure (22) are designed to obtain a preliminary design scheme for the fishway structure; The structural parameters of the vertical slot fishway (23) include the bottom slope of the fishway 、 Fishway design flow rate and total length, fishway bottom slope I and Fishway design flow rate v The specific relationship between it and the total length L of the fishway is: In the formula I is the slope of the fishway bottom; n is the number of pool chambers (30), v Design flow rates for fish passes; g is the acceleration due to gravity; is the velocity coefficient of the partition (32); l y is the net length of the pool chamber (30); k 2 is the net length ratio coefficient; k 1 is the quantity proportional coefficient; L is the total length of the fishway; d is the thickness of the partition (32).

2. The method for designing a canal fishway according to claim 1, characterized in that: Step S1 of evaluating the swimming ability of target fish species passing through the fishway and determining the migratory ecological characteristics of the target fish species includes the following steps: S11. Confirm the hub structure and the purpose of fish passage at the hub; S12. Classify estuarine fish communities based on the interaction between freshwater runoff and saltwater intrusion, and obtain the classification results of fish species that pass through the estuary; S13. Based on the fish classification results, the ecological habits of each fish species are determined. Based on the ecological habits of each fish species, the size and season of the fish species passing through the passage are determined. Initial technical parameters for the fishway are formulated, and fish species that meet the requirements are obtained. Initial technical parameters for the fishway include the number of fishways, the designed flow rate of the fishway, the layout of the fishway, the structure of the fishway, the inlet and outlet of the fishway, the water consumption of the fishway, and the operating water level of the fishway. S14. Determine the time period for fish passage at the fishway at the hub (1) based on the fish passage season; S15. During the fish passage time period confirmed in step S14, the swimming ability of the fish obtained in step S13 is tested at the hub (1), and the swimming ability test results of different fish are obtained to clarify the migratory ecological characteristics of the fish passing through the hub (1).

3. The method for designing a canal fishway according to claim 2, characterized in that: Test the fish's current-seeking characteristics and ability to overcome currents. Test indicators include induced flow velocity, critical swimming speed, and surging swimming speed. Among them: The specific induction flow rate test is as follows: Place more than 10 fish in a test ring-shaped test tank and gradually increase the flow rate until half of the test fish turn back to the upstream direction. The flow rate at this time is the induced flow rate of the test fish group. Place the test fish individually in the still water of the test annular test tank, then gradually increase the flow rate until the test fish turns in the countercurrent direction. The flow rate at this time is the induced flow rate of the individual test fish; The critical swimming speed test is specifically: The body length and weight of the test fish were measured and the fish were placed in the swimming area (12) of the annular test tank. The initial flow velocity, flow velocity gradient and time gradient of the annular test tank were set; Dissolved oxygen and temperature were tested at regular intervals. When the fish reached the end grid of the swimming area and could no longer swim, they were removed from the swimming area (12) and their weight was tested. The critical swimming speed was calculated by assuming that the swimming speed of the fish was equal to the water flow speed and ignoring the retention effect. The swimming ability of the knife-toothed anchovy is tested by analogy with that of the seven-thread anchovy.

4. The method for designing a canal fishway according to claim 1, characterized in that: Step S3 specifically includes the following steps: S31. Design a local cross-sectional physical model of the fishway project based on the preliminary design scheme, wherein the local cross-sectional physical model of the fishway project is designed as a normal model and is designed according to the gravity similarity criterion. The overall fishway model design scheme is also checked for geometric similarity, water flow similarity, and dynamic similarity. S32. Conduct a fishway cross-section model test, measure and evaluate fishway parameters, and find out the parameters that exceed the standard and the reasons for the parameters exceeding the standard, wherein the fishway parameters include the water level difference between the upstream and downstream of adjacent chambers (30), the flow velocity distribution of the vertical slits (31), the flow field distribution in the chambers (30), the flow state in the chambers (30) and the local water flow in the chambers (30), and the average water depth of each chamber (30), the average water level difference of each chamber (30), the flow velocity distribution of the vertical slits (31) of each chamber (30), and the flow field distribution in the chambers (30); S33. After improving the cause in S32, repeat S31-S33 until all fishway parameters meet the design requirements, and form a recommended scheme for the pool chamber (30) structure based on the fishway parameters.

5. The method for designing a canal fishway according to claim 4, characterized in that: In step S31, based on the preliminary design of the vertical slot fishway (23), the bottom slope of the pool chamber (30) is determined. I , the average low tide level at the estuary, the operating water level at the outlet of the vertical slot fishway (23), and the lowest water depth in the pool chamber (30); determine the corresponding design low water level condition upstream of the fishway, the corresponding design low water level condition downstream of the fishway, and the most unfavorable design condition, and design the bottom slope based on the pool chamber (30) I The local cross-section physical model of the fishway project is designed based on the following conditions: the average low tide level at the estuary, the operating water level at the outlet of the vertical slot fishway (23), the lowest water depth in the pool chamber (30), the corresponding design low water level condition upstream of the fishway, the corresponding design low water level condition downstream of the fishway and the most unfavorable design condition. Among them, the most unfavorable design condition is the condition where the volume of the energy dissipation water body is the minimum value on the basis of the unchanged geometric scale of the pool chamber (30).

6. The method for designing a canal fishway according to claim 4, characterized in that: In step S32, the flow velocity distribution of the vertical slit (31) is evaluated as follows: Measuring the flow velocity of at least part of the vertical slits (31), arranging a plurality of measuring points at intervals along the water depth vertically on the center line of each vertical slit (31), and obtaining the flow velocity distribution and average flow velocity of the vertical slit (31) based on the measuring points; Based on the swimming ability test results of the target fish species, the recommended range of flow velocity distribution and the recommended average flow velocity value of the vertical slit (31) are obtained; Evaluate whether the flow velocity distribution of the vertical seam (31) exceeds the recommended range of the flow velocity distribution of the vertical seam (31), and whether the average flow velocity of the vertical seam (31) is greater than the recommended value of the average flow velocity of the vertical seam (31); The velocity coefficient of the baffle (32) is obtained based on the average vertical velocity of the fish passage slit (31), the average water level difference of the baffle (32), the average flow rate of the fishway and the water volume of the pool (30). φ and the unit water power dissipation E of the pool chamber (30), and the velocity coefficient φ of the partition plate (32) and the unit water power dissipation E of the pool chamber (30) meet the design requirements.

7. The method for designing a canal fishway according to claim 4, characterized in that: In step S32, the flow field distribution in the pool chamber (30) is evaluated as follows: A pool chamber (30) is selected to measure the surface flow field distribution thereof, N measuring lines are set along the width of the pool chamber (30), and L measuring points are arranged along the length of each measuring line of the pool chamber (30); Based on the test results of the measuring points, the mainstream entry form, mainstream path, circulation position and recirculation zone integrity of the pool chamber (30) are evaluated, wherein the recirculation zone influence range is K 3 and maximum flow rate in the recirculation zone v cmax to quantify the impact of recirculation zones on fish.

8. The method for designing a canal fishway according to claim 4, characterized in that: Influence range through recirculation zone K 3 and maximum flow rate in the recirculation zone v cmax To quantify the impact of the recirculation zone on fish, specifically: K 3= L c B c / ( LB ), where L c is the maximum length of the recirculation zone, B c is the maximum width of the recirculation zone, L The chief of the fishway, B is the width of the vertical seam (31).

9. The method for designing a canal fishway according to claim 8, characterized in that: Recirculation zone impact range K 3 is 0.12~0.17; the reflux intensity range is 0.18~0.24m / s.

10. The method for designing a canal fishway according to claim 8, characterized in that: When the influence range of the recirculation zone is too large, based on the diversion angle at the vertical slit (31) in the preliminary design scheme, at least a second diversion angle and a third diversion angle are set, and the second diversion angle and the third diversion angle are respectively substituted into the local section physical model of the fishway project to form a new local section physical model of the fishway project, and the new fishway section model test is carried out to obtain the average flow velocity of the vertical slit (31), the maximum flow velocity of the vertical slit (31), and the minimum flow velocity of the vertical slit (31) under various diversion angles, and obtain an optimized structural scheme, wherein the second diversion angle and the third diversion angle are both greater than the diversion angle at the vertical slit (31) in the preliminary design scheme.

11. The method for designing a canal fishway according to claim 10, characterized in that: Based on the optimized structural scheme, the water level difference of the pool chamber (30), the flow velocity distribution of the vertical seam (31), and the flow field distribution in the pool chamber (30) are calculated, and it is confirmed whether the water level difference of the pool chamber (30), the flow velocity distribution of the vertical seam (31), and the flow field distribution in the pool chamber (30) meet the design requirements. If so, the optimized structural scheme is the recommended structural scheme for the pool chamber (30).

12. The method for designing a canal fishway according to claim 4, characterized in that: Step S4 specifically includes the following steps: S41: Establish the overall model design of the fishway based on the preliminary design and the recommended structure of the chamber (30); S42: Based on the overall fishway model design scheme, a fishway overall model is produced. The overall fishway model is designed as a normal model and is designed according to the gravity similarity criterion. The overall fishway model design scheme is also checked for geometric similarity, water flow similarity, and dynamic similarity. S43: Conduct fishway overall model tests based on the fishway overall model to optimize the overall fishway layout structure and operation plan, thereby obtaining the final fishway overall structure plan.

13. The method for designing a canal fishway according to claim 12, characterized in that: Step S41 specifically includes the following steps: Establish the basic structure of the fishway overall model design based on the preliminary design plan; A pool chamber (30) structural scale scheme is established based on the optimized local cross-section structural scheme of the fishway project, and the pool chamber (30) structural scale scheme is added to the basic structural scheme of the overall model design of the fishway to obtain the overall model design scheme of the fishway; The experimental operating conditions are selected according to the upstream design operating water level and the downstream design operating water level of the fishway, wherein the experimental operating conditions include the upstream maximum operating water level condition, the upstream minimum operating water level condition, the downstream minimum operating water level condition, the condition where the inlet water depth is the same as the outlet water depth when the upstream maximum water level is the same, and the maximum operating water level condition; Based on the production of the fishway overall model and various experimental working conditions, the fishway overall model test is carried out to obtain the water depth in each pool chamber (30) and the average height difference between the pool chambers (30) in each working condition.

14. The method for designing a canal fishway according to claim 13, wherein: Based on the overall model test of the fishway, the flow velocity of the vertical slit (31), the flow velocity and flow pattern of the pool chamber (30), the flow velocity and flow pattern in the rest pool (36), and the flow velocity and flow pattern at the inlet and outlet of the vertical slit fishway (23) under various working conditions were obtained.

15. The method for designing a canal fishway according to claim 13, wherein: When the vertical slits (31) in the fishway trough body and the flow rate in the fish pond exceed the design requirements, the flow rate of the vertical slit fishway (23) trough body is reduced to adapt to the water depth of the fishway lower section chamber (30) under low water level conditions.

16. The method for designing a canal fishway according to claim 13, wherein: When the vertical slits (31) in the fishway body and the flow rate in the fish pond exceed the design requirements, the water depth of the flow rate exceeding pool chamber (30) is increased and the flow rate is reduced.

17. A canal fishway structure, characterized in that: The canal fishway is designed by the design method of any one of claims 1 to 16, wherein the structure of the canal fishway includes an eel way (24) and a vertical slit fishway (23), wherein the migratory fish in the eel way (24) include eels and mitten crabs, and the migratory fish in the vertical slit fishway (23) include red-eyed trout and dace, and the eel way (24) and the vertical slit fishway (23) are located on the same side of the canal, one end of the eel way (24) is connected to the middle of the vertical slit fishway (23), and the other end extends to the bottom of the canal, and a climbing matrix (20) is provided in the eel way (24), and the vertical slit fishway (23) is located between the eel way and the vertical slit fishway. Water retaining structures are provided at intervals upstream of the fishway (24), and a pool chamber (30) is formed between adjacent water retaining structures. The water retaining structure includes a partition (32) and a guide plate (35) that are arranged opposite to each other. The guide plate (35) is smaller in width than the partition (32). A vertical slit (31) for fish to pass through is provided between the partition (32) and the guide plate (35). A climbing matrix (20) is also provided in the pool chamber (30). The climbing matrix (20) includes a plurality of rows of pile structures (22), wherein each row is provided with at least two pile structures (22) at intervals, and adjacent rows of the pile structures (22) are staggered along the length direction of the eel way (24) or the vertical slit fishway (23).

18. A method for constructing a fishway, characterized in that: The method for forming the canal fishway structure according to claim 17 comprises the following steps: S1: Construction of vertical slot fishway (23); S2: constructing an eel way (24) and connecting the eel way (24) with the vertical slit fishway (23); S3: Adjust the slope and diversion angle of the eel channel (24).

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