Evaluation method based on fish swimming ability

Abstract

The invention relates to the field of evaluation methods based on fish swimming ability, in particular to an evaluation method based on fish swimming ability. The evaluation method comprises the following steps: confirming a canal cascade channelization channel grade, and arranging a three-stage cascade hub; confirming a fish passing purpose at a downstream third hub; classifying the estuary fish communities; determining the types of canal estuary migratory fishes and ecological habits of estuary fishes, and determining fish passing specifications; determining a fish passing time period of the fishway at the third hub based on the fish passing season and the fish passing time period; in the fish passing time period, the swimming ability of the fishes is tested at the third hub, the swimming ability test result is obtained, and the migration ecological characteristics of the fish passing object of the third hub are determined; and determining a design index of the third hub fishway. According to the evaluation method based on the swimming ability of the fishes, the swimming ability of the target fishes passing through the fishway is studied, and the migration ecological characteristics of the fishes passing through the fishway are defined, so that the design indexes of the third hub fishway are determined, and a theoretical reference basis is provided for the design of the third hub fishway.

Description

Technical Field

[0001] The invention relates to the field of fish swimming ability evaluation methods, and in particular to a fish swimming ability evaluation method. Background Art

[0002] After the construction of permanent river-blocking structures on rivers, the original continuous river ecosystem is divided into discontinuous environmental units. The most direct adverse impact on fish is the blocking of migration channels. This is often devastating for migratory and semi-migratory species that need to migrate over a large area to complete their life history. They cannot reach their original breeding grounds or feeding grounds to complete their life history, and their resource volume will be seriously affected. For species that can complete their life history in local waters, it may affect the genetic exchange between different water groups, resulting in a decrease in the overall genetic diversity of the population and the degradation of fish quality. For some rare and endangered fish, they may face the risk of extinction. In order to ensure the migration of fish in the engineering river section, it is necessary to set up fishway projects at the hub, restore the connectivity of the canal, and provide migration channels for fish and crabs. In the actual process, how to evaluate the swimming ability of fish before designing fishways, simulated natural channels, and fish locks has become an important research direction for technicians in this field. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiency in the prior art that there is currently no better evaluation method for fish swimming ability, and to provide an evaluation method based on fish swimming ability.

[0004] In a first aspect, the present invention provides an evaluation method based on the swimming ability of fish, comprising the following steps:

[0005] S1. Confirm the canal cascade channelization level, divide the canal into sections based on the river conditions, plan to straighten the canal, arrange three-level cascade hubs on the canal, namely the first hub, the second hub and the third hub from upstream to downstream, and confirm the dredging excavation volume;

[0006] S2. Determine the water demand of the river and the average water consumption over many years based on the functional positioning of the canal and the comprehensive utilization parameters of water resources;

[0007] S3. Confirm the fish passing purpose at the third downstream hub;

[0008] S4. Classify estuarine fish communities based on the interaction between freshwater runoff and saltwater intrusion;

[0009] S5. Confirm the species of river-sea migratory fish and upstream migratory fish at the canal estuary and the ecological habits of estuarine fish, confirm the specifications of fish, and obtain fish that meet the requirements;

[0010] S6. Determine the time period for fish passage in the fishway at the third hub based on the fish passage season and the fish passage period;

[0011] S7. During the fish passage time period confirmed in step S6, the fish obtained in step S5 are tested for swimming ability at the third hub, and the swimming ability test results of different fish are obtained to clarify the migratory ecological characteristics of the fish passage objects at the third hub;

[0012] S8. Determine the design indicators of the third hub fishway based on the migratory ecological characteristics of the fish passing through the third hub.

[0013] The present application describes an evaluation method based on fish swimming ability, which studies the swimming ability of target fish passing through the fishway, clarifies the migratory ecological characteristics of the fish passing through the fishway, thereby determining the design indicators of the third hub fishway and providing a theoretical reference basis for the design of the third hub fishway.

[0014] Preferably, in S5, the river-sea migratory fish species include eel, flower eel and spotted sea bass; the upstream migratory fish species include seven-thread anchovy and spotted mullet.

[0015] Preferably, the portion of the canal located downstream of the third hub is a tidal river section.

[0016] Preferably, in step S7, an annular water tank is provided at the third hub, and a swimming area is provided in the water tank, so that the fish swim in the swimming area, the water flow speed is artificially controlled and set, and the swimming speed and swimming ability of the fish are calculated according to the water flow speed.

[0017] Preferably, the swimming ability of the fish is tested to compare the swimming ability of fish of similar species and size to the target fish, and determine the design flow rate of the fishway set at the third hub.

[0018] Preferably, the swimming ability of fish is tested by an annular test water tank, which includes a strip elliptical annular flow channel, a swimming area is arranged in a straight segment area on one side of the strip elliptical annular flow channel, a flow stabilizer is arranged at one end of the swimming area, and a grille is arranged at the other end, a propeller flow meter for longitudinal air outlet is arranged in the straight segment area on the other side of the strip elliptical annular groove structure, and the rotating blades are driven to rotate by a motor, and the motor is controlled by a frequency converter.

[0019] Preferably, the flow rate in the annular test water tank is gradually increased by adjusting the operating frequency of the motor, the flow rate in the water tank is tested for each unit increase in the motor frequency, a standard curve is prepared, and a linear fit is performed on the standard curve.

[0020] Preferably, the fitting equation of the flow velocity-frequency curve of the test annular test water tank is: y=0.0474x-0.036, R2=0.999, wherein y is the flow velocity; x is the frequency, and R2 is the width of the strip elliptical annular flow channel.

[0021] Preferably, the fish's current-seeking characteristics and ability to resist current are tested. Test indicators include induced flow velocity, critical swimming speed and surging swimming speed.

[0022] Preferably, the induction flow rate test is specifically:

[0023] Place more than 10 fish in a test annular test tank, and gradually increase the flow rate until half of the test fish turn around to the countercurrent direction. At this time, the flow rate is the induced flow rate of the test fish group;

[0024] Place the test fish individually in the still water of the test annular test tank, and then gradually increase the flow rate until the test fish turns to the countercurrent direction. At this time, the flow rate is the induced flow rate of the individual test fish;

[0025] Preferably, the critical swimming speed test is specifically:

[0026] The body length and weight of the tested fish are measured and the fish are placed in the swimming area of ​​the annular test tank, and the initial flow velocity, flow velocity gradient and time gradient of the annular test tank are set;

[0027] The dissolved oxygen and temperature were tested at regular intervals. When the fish reached the end grid of the swimming area and could not swim, they were removed from the swimming area and their weight was tested. It was assumed that the swimming speed of the fish was equal to the water flow speed and the retention effect was ignored to calculate the critical swimming speed.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present application describes an evaluation method based on fish swimming ability, which studies the swimming ability of target fish passing through the fishway, clarifies the migratory ecological characteristics of the fish passing through the fishway, thereby determining the design indicators of the third hub fishway and providing a theoretical reference basis for the design of the third hub fishway. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a chart of the fishing time periods for different fish species used in this application.

[0031] Figure 2 This is a schematic diagram of the annular test water tank structure of this application.

[0032] Figure 3 It is a schematic diagram of the flow velocity-frequency fitting curve in the annular test flume structure of the present application.

[0033] Figure 4This is a schematic diagram of the correlation between the eel's induced flow velocity and body length in this application.

[0034] Figure 5 This is a schematic diagram of the correlation between the critical swimming speed and body length of the eel in this application.

[0035] Figure 6 This is a schematic diagram of the correlation between the eel's swimming speed and body length in this application.

[0036] Figure 7 This is a schematic diagram of the correlation between the induced flow velocity and body length of the striped seabass in the present application.

[0037] Figure 8 This is a schematic diagram of the correlation between the critical swimming speed and body length of the striped seabass in this application.

[0038] Fig. 9 This is a schematic diagram of the correlation between the diving swimming speed and body length of the striped seabass in this application.

[0039] Fig.10 This is a schematic diagram of the correlation between the induced flow velocity and body length of the red-eyed trout in this application.

[0040] Fig.11 This is a schematic diagram of the correlation between the critical swimming speed and body length of the red-eyed trout in this application.

[0041] Fig.12 This is a schematic diagram of the correlation between the red-eyed trout's lunging swimming speed and body length in this application.

[0042] Fig.13 This is a schematic diagram of the correlation between the induced flow velocity and body length of the dace in the present application.

[0043] Fig.14 This is a schematic diagram of the correlation between the critical swimming speed and body length of the dace in the present application.

[0044] Fig.15 The present invention relates to the correlation between the swimming speed and body length of the dace.

[0045] Fig.16 This is a schematic top view of the pool chamber structure of the present application.

[0046] Fig.17 This is a three-dimensional schematic diagram of the pool chamber structure of this application.

[0047] Fig.18 This is a schematic diagram of the overall structure of the fishway in this application.

[0048] Fig.19 This is a schematic diagram of the structure when the pile structure of this application is a boss.

[0049] Fig. 20 Schematic diagram of the pile structure when the pile structure is a pipe structure for this application

[0050] Fig.21 This is a top view of the eel channel structure of this application. DETAILED DESCRIPTION

[0051] The present invention is further described in detail below in conjunction with specific embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0052] 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 all based on the expression of the orientation or position relationship shown in the drawings, or are the orientation or position relationship when the invented product / equipment / device is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so as to facilitate the technicians to quickly understand the scheme, 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 cannot be understood as a limitation on the present invention.

[0053] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or 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 set in directions such as "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.

[0054] In addition, the expressions “first”, “second”, “third”, etc., which appear in the terms, are merely used to distinguish the description of the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.

[0055] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be any number such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.

[0056] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0057] Example 1

[0058] like Figure 1-21 As shown in the figure, the swimming ability of target fish species in the fishway is studied to clarify the migratory ecological characteristics of the third hub fish species

[0059] The main fish species in the fishway are downstream migratory fish (CA) such as flower eel, eel, and flower perch, upstream migratory fish (AN) such as seven-thread anchovy and flower mullet, and historically distributed freshwater fish such as red-eye trout and dace; other fish species that are also considered are spotted mullet, Chinese black mullet, spotted tongue goby, silverfish, tongue goby, semi-ridged Chinese fish, and Hepu mitten crab. The fish passing season is from November to September of the following year. The main fish species passing through the vertical slot fishway are 40-600mm in size, and the fish species passing through the eel channel are 100-500mm in size.

[0060] By testing the swimming ability of the main fish species of the third hub fishway, such as sea bass, eel, red-eyed trout, and dace, as well as the fish currently distributed in this section of the river, the design indicators of the third hub fishway were comprehensively determined: the flow velocity range of the fish holes / slits of the vertical slot fishway is 0.54~1.37m / s, and the average flow velocity can be about 1.0m / s; the average flow velocity in the pool chamber is 0.24~0.67m / s; the inlet fish-attracting flow velocity should not be lower than the fish-sensing flow velocity of 0.2m / s, and should be 0.35~0.73m / s; the outlet flow velocity should not be still water, and should be 0.24~0.35m / s; eels are fish with climbing habits, and the eel way should not be simply designed based on the measured swimming ability, but can be designed as a steeper slope, but staggered cylindrical tubes or piers should be designed at the bottom to provide a fulcrum for their climbing.

[0061] Step 1: Confirm that the overall terrain of the canal is high in the north and low in the south. For the upstream water diversion river section, dig a watershed to connect at least three rivers upstream, and plan to achieve the Class I waterway standard through cascade channelization in this section. The canal is divided into four route sections based on the river conditions: Shaping River Section, Watershed Section, Main Stream Section, Urban Section, and Estuary Nearshore Section. The waterway is straightened at 57 locations. The canal is arranged in three levels, from the upstream side of the Yujiang River to the estuary, they are the first hub, the second hub, and the third hub, with a dredging and excavation volume of 60 million m 3 .

[0062] Step 2: According to the functional positioning of the canal, the parameters for comprehensive utilization of water resources mainly consider the water demand for water outside the river and the water demand for navigation at the hub. The water users outside the river along the canal are mainly three types of water users: residents, industry and agricultural irrigation. The average annual water consumption outside the river between the first hub and the second hub is 0.1m3 / s, and the average annual water consumption outside the river between the second hub and the third hub is 13.9m3 / s, including 1.6m3 / s for irrigation and 12.3m3 / s for industrial and domestic water. Under the condition of water conservation, the water demand for navigation at the first hub is 24m3 / s, the water demand for navigation at the second hub is 24m3 / s, and the water demand for navigation at the third sluice is 10.86m3 / s (10.06m3 / s from May to January of the following year).

[0063] Review of the swimming ability of target fish species

[0064] Step 3: The third hub is the last step of the canal. The downstream is a tidal river section. After the canal is built, the downstream will be deepened due to the requirements of the waterway, which may aggravate the upstream movement of salt water, resulting in an increase in the salinity of the downstream habitat. The number of estuarine fish species that migrate upstream to the lock may increase simultaneously. At the same time, these fish have the need to migrate between seawater and freshwater at different stages of their life history. The construction of a fishway at the third hub can provide them with upstream and downstream channels. Therefore, the main purpose of fish passage at the third hub is adjusted to: connect the migratory channels of river-sea migratory fish, provide upstream conditions for estuarine fish, and provide migratory channels and gene exchange channels for freshwater fish.

[0065] Step 4: Since estuarine waters are subject to the interaction of freshwater runoff and seawater intrusion, the habitat types are very complex, and estuarine fish communities are divided into six ecological groups: Estuarine resident fish: the entire life cycle takes place in estuarine waters; Occasional marine fish: live in the ocean for most of their life cycle and occasionally go to estuarine waters for foraging; Downstream migratory fish: mainly inhabit freshwater rivers, use estuaries as important migration channels, and spawn in the ocean; Upstream migratory fish: unlike downstream migratory fish, they spawn in freshwater rivers, but raise their young and forage in estuarine waters, and adult fish mostly live in the ocean; Marine migratory fish: live in near-shore waters for part of their life cycle, but estuarine waters are important foraging and rearing places, and are also important habitats for adult and juvenile fish; Freshwater fish: all stages of their life cycle are spent in the freshwater environment of the river area adjacent to the estuary.

[0066] Step 5: The fish species migrating from the canal estuary to the sea mainly include eel, flower eel, and flower perch, etc. The fish species migrating upstream mainly include seven-thread anchovy and flower mullet, etc.

[0067] For example: a total of 119 species of canal fish were found, belonging to 10 orders, 29 families and 84 genera. There are 3 species of river-sea migratory fish, namely eel, flower eel and seven-thread anchovy; there are 8 species of estuarine fish, namely flower shad, spotted shad, spotted sea bass, Chinese black snakehead, spotted tongue goby, silverfish, tongue goby and half-ridged Chinese [fish mang], which are distributed in the downstream section of the third hub. It is necessary to prevent the construction of the third hub from causing the distribution of river-sea migratory fish species in the upper reaches of the canal. Taking eels as an example, the canal has an estuary, which is a channel for long-distance migration of eels and other fish. Ecological habits of estuarine fish: Taking flower eel, eel, seven-thread anchovy, flower shad and Chinese black snakehead as examples:

[0068] Flower eel: Flower eel is a downstream migratory fish. In winter, the gonads begin to develop near the river mouths, and then enter the deep sea to spawn and reproduce. From March to April every year, young eels begin to enter the river mouths to feed and grow upstream, and live in caves in rivers and streams. Flower eels can climb a certain height to wade through sluice gates to enter mountain streams and valleys.

[0069] Eel: Eel is a type of catadromous fish, originally from the sea, which swims upstream to fresh water to grow up, and then returns to the sea to lay eggs. Every spring, large numbers of young eels [also called white eels and eel lines] enter the river estuaries from the sea in groups. Male eels usually grow up at the river estuaries; while female eels swim upstream to the main streams, tributaries and lakes connected to rivers, and some even travel thousands of kilometers to reach the upper reaches of rivers.

[0070] Seven-filament Coilia: Seven-filament Coilia is a typical upstream migratory fish. Its hatching and early life history need to be completed in fresh water. In the subsequent growth and development stages, it flexibly travels between the brackish water and fresh water areas of the estuary. However, unlike the migration patterns of other Coilia fish in my country, the migration activities of Seven-filament Coilia in the Pearl River Estuary are more diverse, and there are differences in the "resume" of stream migration between individuals, reflecting the diversity and complexity of the survival strategies of Seven-filament Coilia in the life history.

[0071] Flowery croaker: Belongs to the genus Lurpula of the family Lupulidae in the order Lupuliformes, commonly known as yellow croaker, widely distributed in the northwest Pacific Ocean, especially in Vietnam, Thailand, South Korea and coastal areas of my country. It is a common mid- and upper-level migratory economic fish in the lower reaches of the Pearl River and the Pearl River Estuary. It usually lives in brackish and fresh water areas. Its spawning period is from April to August. During the spawning season, it migrates to estuaries or inland rivers to spawn.

[0072] Chinese black mullet: The Chinese black mullet can tolerate salinity of 0-35‰, with a more suitable salinity of 10-25‰. The suitable salinity for seedlings is about 15‰, which is similar to the salinity in the mangrove area of ​​Guangxi in April. It is speculated that Chinese black mullet mates and reproduces in April. The temperature range of Chinese black mullet is 6.0-35.0℃, and the ideal water temperature is 25-30℃.

[0073] Step 6: After the third hub is newly built, the downstream is a tidal river section, and the water flow habitat will change to a certain extent. Therefore, the main fish passing objects of the third hub fishway are downstream migratory fish (CA), upstream migratory fish (AN), and freshwater fish with historical distribution.

[0074] Therefore, after the review, the main fish species that can be passed are: downstream migratory fish (CA) flower eel, eel, and flower perch, upstream migratory fish (AN) seven-thread anchovy and flower mullet, historically distributed freshwater fish red-eye trout and dace; the objects that can be taken into consideration are: spotted mullet, Chinese black mullet, spotted tongue goby, Ju's silverfish, tongue goby, semi-ridged Chinese [fish mang] and other estuarine fish, and Hepu mitten crab. The fish species that can be passed during the environmental assessment stage have been adjusted to a certain extent, mainly to adjust seven-thread anchovy, flower mullet and other fish with sea-river migratory characteristics to the main fish species, and to increase estuarine fish such as Chinese black mullet and spotted tongue goby to the objects of consideration.

[0075] Step 7: Fishing Season

[0076] The fish season in the environmental impact assessment report is from February to November, and the fish season in the feasibility report is from February to October. The fish season is reviewed and determined based on the reselection of the fish objects and the sorting out of their migration seasons. Figure 1 As shown:

[0077] From December to May of the following year, young eels at the mouth of the canal migrate upstream in groups to the estuary and migrate into freshwater rivers.

[0078] The gonadal development of male and female Coilfish is basically the same. The parents spawn twice a year. The first spawning period is from February to March, and the spawning is completed in April. After that, the parent population moves to the open sea. The individual body length of the young fish found in May has reached 40 to 50 mm. In autumn, the spawning fish gather at the estuary again and spawn for the second time in August and September.

[0079] The spotted bream usually lives in brackish and freshwater areas. Its spawning period is from April to August. During the spawning season, it migrates to estuaries or inland rivers to lay eggs.

[0080] The spawning period of goby is from April to August every year.

[0081] To sum up, the fishing season of the fishway at the third hub is from November to September of the following year, and it can be shut down for dredging and maintenance in October.

[0082] Step 8: Confirm the fish size

[0083] The length of sexually mature females is 100-290mm, with the smallest sexually mature individual being 102mm long and weighing 4.5g; the length of males is 90-220mm, with the smallest sexually mature individual being 90mm long and weighing 3g. The common length of the flower bream is 40-240mm. The length of a sexually mature 3-year-old flower perch is up to 600mm. The length of young eels that reach the estuary in my country is 100-200mm; in the eel fishway on the St. Lawrence River in the United States, the length of the eels migrating upstream ranges from 300 to 500mm.

[0084] In summary, the main specification range of fish passing through the third hub vertical slot fishway is 40 to 600 mm. The specification of fish passing through the eel channel is 100 to 500 mm.

[0085] Step 9. Swimming ability test test method

[0086] At present, there are four main methods for testing fish swimming ability:

[0087] The fish move in a straight line in a still water tank. Bait is delivered at both ends. The fish move back and forth. An underwater camera is used to film the fish's movement behavior and the movement distance and time are used to estimate the fish's swimming speed and swimming ability.

[0088] Using a large diameter still water annular tank, fish followed the movement of visual markers, which moved at speeds ranging from 0 to 4.5 m / s.

[0089] Fish move in a circular water tank. The water flow in the tank is set and controlled artificially. The swimming speed and swimming ability of the fish are calculated based on the position of the fish's movement and the water flow rate.

[0090] Using a portable annular water tank, fish move in a specific swimming area in the tank, the water flow speed is set manually, and the swimming speed and swimming ability of the fish are calculated based on the water flow speed.

[0091] This test uses the fourth method.

[0092] Test time and location: The test time is September-October 2022; the test location is near the third hub of the canal in Qinbei District, Qinzhou City, Guangxi Zhuang Autonomous Region.

[0093] Step 10: Test fish: Based on the types of fish passing through the previous stage, the types of fish passing through after verification, and the availability of fish in the canal section, the project team tested the swimming ability of sea bass and eel, as well as red-eyed trout, dace, and other fish currently distributed in the river section. By consulting the data and comparing the swimming ability of fish of similar species and body size to the fish passing through, the design flow rate of the third hub fishway was comprehensively determined. The specifications of the test fish are shown in Table 1.

[0094] Table 1 Test fish species and specifications

[0095] Fish species Body length cm Average body length cm Eel 18.5～26.8 22.0 Lateolabrax 33.0～37.0 35.5 Redeye Trout 17.5～28.4 22.3 Dace 16.8～27.1 20.8

[0096] After the target fish in the canal are captured, they are temporarily kept in an aquarium and oxygenated. The test begins 24 hours after the fish are temporarily kept to reduce the stress response of the fish. When the test fish need to be transported during the test, a fine net and a bucket with water are used to transport the fish, which will cause less damage to the fish, so as to reduce the impact on the test fish.

[0097] Test equipment:

[0098] The water tank for testing the swimming ability of fish is designed as a circular test water tank 1, such as Figure 2 As shown. Specifically and preferably: the swimming ability of fish is tested by an annular test water tank (1), the annular test water tank (1) comprises a strip elliptical annular flow channel (11), a swimming area (12) is arranged in a straight section area on one side of the strip elliptical annular flow channel (11), a flow stabilizer (13) is arranged at one end of the swimming area (12), and a grille (14) is arranged at the other end, and a vortex flow meter (15) for longitudinal air discharge is arranged in a straight section area on the other side of the strip elliptical annular groove structure (11), the rotating blade (15) is driven to rotate by a motor (16), and the motor (16) is controlled by a frequency converter (17). The annular test water tank 1 comprises a LGY-Ⅱ type vortex flow meter for flow velocity calibration before the test. During the test, a DO200 type dissolved oxygen meter is used to measure dissolved oxygen and temperature, and the local air pressure value is input before use for dissolved oxygen calibration, so that the purpose of real-time monitoring of water temperature and dissolved oxygen is achieved during the test of the fish swimming ability test water tank schematic diagram.

[0099] By adjusting the motor operating frequency (f, Hz) to gradually increase the flow velocity (v, m / s) in the water tank, the flow velocity in the annular test water tank 1 is tested every time the motor frequency increases by a certain frequency, a standard curve is made, and a linear fit is performed. The fitting equation of the test water tank flow velocity-frequency curve is y=0.0474x-0.036, R2=0.999, where y is the flow velocity; x is the frequency, and R2 is the width of the strip elliptical annular flow channel. .

[0100] Swimming ability indicators:

[0101] There are two main types of indicators that characterize the swimming ability of fish, one is the current-seeking characteristics, and the other is the ability to overcome the flow. The current-seeking characteristics refer to the tendency of fish to flow and the sensitivity of induction. The ability to overcome the flow is the ability of fish to overcome the flow of a certain velocity. These two swimming ability indicators are usually important reference data in the design of fish-passing facilities, and are also one of the key directions of research on fish-passing facilities and fish behavior at home and abroad. Specifically, the current-seeking characteristics of fish are mainly used for the design of the minimum flow velocity that occurs in the migration route; the speed at which fish overcome the flow is mainly used in the design of flow velocity control in fish-passing facilities.

[0102] Tidal characteristics: Tidal characteristics are generally measured by response flow speed. The response flow speed refers to the flow rate that can cause fish to respond to tidal flow. The response to tidal flow is usually indicated by the change in the direction of fish movement. In the design of fishways, the response flow speed is not only an important parameter for the design of the inlet fish attracting flow speed, but also a reference for the design of fish passing facilities and the minimum flow speed in the fish migration route.

[0103] Flow-control ability: According to the different internal movement metabolism patterns of fish and the different apparent movement durations, the flow-control ability of fish is mainly divided into three categories, which are expressed in terms of speed: sustained swimming speed, prolonged swimming speed and burst speed. The difference between these three speeds of some fish can be reflected by the change in the slope of the swimming time and speed relationship graph.

[0104] Sustained swimming speed: Fish can maintain sustained swimming mode for a long time without feeling tired, and its duration is usually calculated as >200min. At this time, fish use aerobic metabolism to provide energy to slowly contract red muscle fibers, thereby propelling the fish forward.

[0105] Endurance swimming speed: The endurance swimming speed of fish is between the sustained swimming speed and the sprint swimming speed, which can usually be maintained for 20s to 200min and ends with fatigue. At this speed, the energy consumed by fish is obtained through both aerobic metabolism and anaerobic metabolism. Anaerobic metabolism provides higher energy, but it is easy to accumulate a large amount of lactic acid, which makes fish feel tired.

[0106] Among them, the most studied critical swimming speed is within the range of endurance swimming speed.

[0107] Burst swimming speed: Burst swimming speed is the maximum speed that fish can reach, and it is maintained for a very short time, usually <20s. At this speed, fish obtain greater energy through anaerobic metabolism and achieve a short-term burst swimming speed, but also accumulate waste products such as lactic acid. According to the different swimming times, burst swimming ability can be divided into burst swimming speed and darting swimming speed. Among them, burst swimming speed refers to the maximum swimming speed that fish can reach in a very short time (<2s), which is usually used when hunting and avoiding danger in an emergency. Defending swimming speed refers to the maximum swimming speed that fish can reach in a relatively short period of time (<20s). Defending swimming speed is an important parameter in fishway design.

[0108] Normally, fish slow down or speed up by adjusting the frequency and amplitude of the swings of their body and tail fin to maintain a burst-and-coast swimming style, which allows fish to reduce the amount of energy they consume.

[0109] Fish often use sustained swimming speed for exercise (e.g. migration), usually use endurance swimming speed in difficult areas, and use burst swimming speed when hunting and escaping. Sustained exercise of fish is considered to be a "marathon" aerobic metabolism exercise of fish. Its sustained swimming speed is the maximum speed at which fish can swim stably for 6 hours without exhaustion. Endurance swimming exercise is a swimming exercise that combines aerobic and anaerobic metabolism of fish. The duration of endurance swimming speed is generally 20s to 200min. The duration of endurance swimming speed is related to the type of fish, individual size, water temperature, and the period of burst swimming and sustained swimming.

[0110] Test content: In order to comprehensively study the swimming ability of fish, this project tests the fish's current-seeking characteristics and ability to overcome currents. The test indicators are: induced flow velocity, critical swimming speed, and aggressive swimming speed.

[0111] Test plan

[0112] Induction flow rate test: The induction flow rate test generally uses the water flow rate corresponding to the fish adjusting the swimming direction as an indicator:

[0113] For group testing, a large number of fish (usually more than 10) are placed in a water tank and the flow rate is gradually increased until half of the test fish turn around and go against the flow. At this point, the flow rate is the induced flow rate of the test fish group.

[0114] Place the test fish individually in the still water of the tank, and then gradually increase the flow rate until the test fish turns to the countercurrent direction. At this time, the flow rate is the induced flow rate of the individual test fish.

[0115] Critical swimming speed

[0116] There are usually two test methods for measuring critical swimming speed: "fixed flow rate method" and "increasing flow rate method".

[0117] Fixed flow rate method: In the fixed flow rate test, the fish are placed in a constant flow rate, and the flow rate does not change during the entire experiment. The fish are first allowed to adapt to the tank for a period of time, and then the flow rate is adjusted to a specific required flow rate, and this flow rate increase must be completed within the specified time. This procedure is repeated many times at different sub-maximal flow rates. In the test of fish swimming ability, in order to avoid differences caused by the influence of the individual environment and physiology. Fixed swimming speed tests 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 incremental flow rate method, which is less time-consuming and has a small sample size, has been mainly used.

[0118] Increasing flow rate method: Before starting the experiment, the fish body length and weight were tested and the fish were placed in the swimming area of ​​the experimental device. The initial flow rate of the experimental device was set to 1bl / s (bl is the body length of the fish), the flow rate gradient was 1bl / s, and the time gradient was 15min. The dissolved oxygen and temperature were tested every 5min. When the fish was fatigued (judgment criterion: the fish reached the end grid of the swimming area and could not swim), the fish was removed from the sealed area and the weight was tested. Since the fish always swims in the swimming area, it can be assumed that the swimming speed of the fish is equal to the water flow speed. The critical swimming speed Ucrit calculation formula is Ucrit = Up + (tf / ti) × Ut, where: Up (bl / s) is the swimming speed of the fish during the entire time period that the fish can swim, Ut (bl / s) is the speed gradient, tf (min) is the time it takes for the fish to increase in speed for the last time until the fish is fatigued, and ti (min) is the time gradient. Since the cross-sectional area of ​​the fish is smaller than 10% of the cross-sectional area of ​​the swimming area, the retention effect can be ignored, that is, there is no need to correct the critical swimming speed.

[0119] The increasing flow rate method has a relatively short test time, strong controllability, and requires a smaller number of fish to obtain statistically significant values. Therefore, the increasing flow rate method was selected to test the critical swimming speed.

[0120] Burst swimming speed: Since the burst swimming speed is maintained for a very short time and the fish's reaction is inconsistent, it is usually difficult for people to grasp such a short time for accurate measurement. Fish cannot always maintain a certain speed. When they swim at high speed, they adopt a "burst-slide" swimming mode. To date, there are still few methods for measuring this behavior. Some use electric shocks to obtain the theoretical value of muscle contraction time; some measure the fish's jumping height to calculate its take-off speed, which can be considered as the fish's maximum burst swimming speed, calculated by the formula V = (2gh) 1 / 2; some international scholars also believe that the burst swimming speed can be obtained by using the incremental flow rate method with the minimum time interval and the maximum flow rate step length. The essence of the burst swimming speed test is to adjust the maximum flow rate step length within the minimum time step length.

[0121] Burst swimming speed is divided into burst speed and burst speed. Burst swimming speed refers to the speed at which fish swim in a very short time.

[0122] The maximum swimming speed reached within (<2s), and the breakthrough swimming speed refers to the maximum swimming speed reached by fish in a relatively short period of time (<20s). In this test, the "increasing flow rate method" with a time step of 20s is used to test the breakthrough speed index value. The increasing flow rate method test is the same as the critical speed test method, with a time step of 20s. The breakthrough swimming speed U breakthrough calculation formula is U breakthrough = Up + (tf / ti) × Ut, where: Up (bl / s) is the swimming speed of the fish during the entire time period that the fish can swim, Ut (bl / s) is the speed gradient, tf (min) is the time it takes for the fish to increase its speed for the last time until the fish is fatigued, and ti (min) is the time gradient. Since the cross-sectional area of ​​the fish is smaller than 10% of the cross-sectional area of ​​the swimming area, the retention effect can be ignored, that is, there is no need to correct the critical swimming speed.

[0123] Comprehensive evaluation of swimming speed: In swimming speed test, some scholars proposed to use the half-endurance (TLm) method to calculate the critical swimming speed, that is, when 50% of the test fish are fatigued, it is considered that the average sustained swimming speed has been reached. This 50% principle is often used in the statistical analysis of swimming speed. Therefore, this test uses the half-endurance (TLm) method to calculate the critical swimming speed and burst swimming speed test values, that is, if 50% of the test fish can overcome a certain flow rate value, then this flow rate value is called the swimming speed index of this type of fish.

[0124] Comprehensive evaluation method for swimming ability: sustained swimming speed range, 0-80% critical swimming speed; endurance swimming speed range, 80% critical swimming speed ~ breakthrough speed; burst swimming speed range, breakthrough speed ~10bl / s (body length / second).

[0125] Test Results

[0126] Eel

[0127] Sensing flow rate: Figure 4 As shown, there are 10 fish in this test, the body length of the tested fish is 0.21-0.27m, and the average body length is 0.23m. The test water temperature is 20.8-27.5℃, and the dissolved oxygen is 5.4-6.67mg / L. The measured induced flow rate is 0.18-0.23m / s.

[0128] Critical swimming speed: Figure 5 As shown, there are 10 fish in this test, the body length of the tested fish is 0.18-0.25m, and the average body length is 0.21m. The test water temperature is 21.8-27.5℃, and the dissolved oxygen is 4.4-5.67mg / L. The critical swimming speed is measured to be 0.56-0.70m / s.

[0129] Swimming speed: Figure 6 As shown, there are 10 fish in this test, the body length of the tested fish is 0.19-0.27m, and the average body length is 0.22m. The test water temperature is 20.7-28.6℃, and the dissolved oxygen is 4.76-5.7mg / L. The measured swimming speed is 0.57-0.95m / s.

[0130] Summary: The half tolerance of the eel's critical swimming speed is calculated to be 0.59m / s, and the half tolerance of the burst speed is 0.73m / s. According to domestic and foreign research results, the upper limit of the sustained swimming speed is near 80% of the critical speed, so the dividing line between the sustained swimming speed and the endurance swimming speed of the eel is near 0.48m / s (0.59m / s×80%). According to the swimming speed range, the burst speed is the lower limit of the burst swimming speed, so the burst speed of 0.73m / s is the dividing line between the endurance swimming speed and the burst swimming speed. The upper limit of the burst swimming speed is 10bl / s.

[0131] Lateolabrax

[0132] Sensing flow rate: Figure 7 As shown, there are 10 fish in this test, the body length of the tested fish is 0.33-0.37m, and the average body length is 0.35m. The test water temperature is 19.9-27.2℃, and the dissolved oxygen is 5.52-6.66mg / L. The measured induced flow rate is 0.07-0.24m / s.

[0133] Critical swimming speed: Figure 8 As shown, there are 10 fish in this test, the body length of the tested fish is 0.33-0.37m, and the average body length is 0.35m. The test water temperature is 19.9-27.2℃, and the dissolved oxygen is 5.52-6.66mg / L. The critical swimming speed is measured to be 0.69-1.38m / s.

[0134] Swimming speed: Fig. 9 As shown, there are 10 fish in this test, the body length of the tested fish is 0.34-0.38m, and the average body length is 0.36m. The test water temperature is 19.4-27.4℃, and the dissolved oxygen is 4.74-5.85mg / L. The measured swimming speed is 1.01-1.80m / s.

[0135] Summary: According to calculations, the half tolerance of the critical speed of the striped bass is 1.14m / s, and the half tolerance of the burst speed is 1.37m / s. According to domestic and foreign research results, the upper limit of the sustained swimming speed is near 80% of the critical speed, so the boundary between the sustained swimming speed and the endurance swimming speed of the striped bass is near 0.91m / s (1.14m / s×80%). According to the swimming speed interval, the burst speed is the lower limit of the burst swimming speed, so the burst speed of 1.37m / s is the boundary between the endurance swimming speed and the burst swimming speed. The upper limit of the burst swimming speed is 10bl / s.

[0136] Redeye Trout

[0137] Sensing flow rate: Fig.10 As shown, there are 10 fish in this test, the body length of the tested fish is 0.19-0.28m, and the average body length is 0.23m. The test water temperature is 25.5-30.1℃, and the dissolved oxygen is 6.82-7.62mg / L. The measured induced flow rate is 0.11-0.15m / s.

[0138] Critical swimming speed: Fig.11 As shown, there are 10 fish in this test, the body length of the tested fish is 0.19-0.28m, and the average body length is 0.23m. The test water temperature is 25.5-30.1℃, and the dissolved oxygen is 6.82-7.62mg / L. The critical swimming speed is measured to be 0.54-1.07m / s.

[0139] Swimming speed: Fig.12 As shown, there are 10 fish in this test, the body length of the tested fish is 0.18-0.26m, and the average body length is 0.21m. The test water temperature is 26.6-30.6℃, and the dissolved oxygen is 6.60-7.97mg / L. The measured swimming speed is 1.02-1.87m / s.

[0140] Summary: The half tolerance of the critical speed of red-eyed trout was calculated to be 0.98m / s, and the half tolerance of the burst speed was 1.45m / s. According to domestic and foreign research results, the upper limit of sustained swimming speed is near 80% of the critical speed, so the dividing line between the sustained swimming speed and the endurance swimming speed of red-eyed trout is near 0.78m / s (0.98m / s×80%). According to the swimming speed range, the burst speed is the lower limit of the burst swimming speed, so the burst speed of 1.45m / s is the dividing line between the endurance swimming speed and the burst swimming speed. The upper limit of the burst swimming speed is 10bl / s.

[0141] Dace

[0142] Sensing flow rate: Fig.13As shown, there are 10 fish in this test, the body length of the tested fish is 0.17-0.26m, and the average body length is 0.20m. The test water temperature is 27.5-29.7℃, and the dissolved oxygen is 6.58-7.23mg / L. The measured induced flow rate is 0.10-0.18m / s.

[0143] Critical swimming speed: Fig.14 As shown, there are 10 fish in this test, the body length of the tested fish is 0.17-0.26m, and the average body length is 0.20m. The test water temperature is 27.5-29.7℃, and the dissolved oxygen is 6.58-7.23mg / L. The critical swimming speed is measured to be 0.79-1.21m / s.

[0144] Swimming speed: Fig.15 As shown, there are 10 fish in this test, the body length of the tested fish is 0.19-0.27m, and the average body length is 0.21m. The test water temperature is 26.9-29.9℃, and the dissolved oxygen is 6.16-7.37mg / L. The measured swimming speed is 1.14-1.97m / s.

[0145] Summary According to the calculation, the half tolerance of the critical speed of the dace is 1.07m / s, and the half tolerance of the burst speed is 1.55m / s. According to the research results at home and abroad, the upper limit of the sustained swimming speed is near 80% of the critical speed, so the dividing line between the sustained swimming speed and the endurance swimming speed of the dace is near 0.76m / s (1.07m / s×80%). According to the swimming speed interval, the burst speed is the lower limit of the burst swimming speed, so the burst speed of 1.55m / s is the dividing line between the endurance swimming speed and the burst swimming speed. The upper limit of the burst swimming speed is 10bl / s.

[0146] Swimming speed analysis: According to the test results of the swimming ability of the tested fish, as shown in Table 2, the swimming speed analysis is shown in Table 3.

[0147] Table 2 Swimming ability test results

[0148]

[0149]

[0150] Table 3 Swimming speed classification

[0151]

[0152] Note: The swimming ability test results of the knife-toothed anchovy are derived from the "Special Report on the Study of Fish Habits in Poyang Lake", which is used to compare with the seven-thread anchovy.

[0153] Except for the striped perch, most of the fish passage objects tested were within the fish passage specification range. However, since the striped perch is larger than other fish and has stronger swimming ability, the swimming ability of the striped perch does not constitute a restrictive condition. The main controlling condition for the fishway is reflected in the structural size.

[0154] Design flow rate of fish passage facilities:

[0155] Vertical slot fishway

[0156] Flow rate of fish holes / slots in fish passing facilities: The boundary condition for the flow rate design of the control section of the fish passing facility is to ensure that there is a 0.10m low flow rate area near the bottom wall of the fish hole for the middle and bottom fish to pass through. The flow rate in this area is in the range of 0.29-0.54m / s. The remaining high flow rate area in the middle is mainly for large individual fish to sprint through, and the maximum endurance speed is taken. The flow rate range of the fish hole / slot is 0.54-1.37m / s, and the average flow rate can be about 1.0m / s.

[0157] Imported fish attracting flow rate: The preferred flow rate of fish is generally within the range of their sustained speed. FAO believes that 60%-80% of the critical swimming speed is acceptable. According to test results, the imported fish attracting flow rate should not be lower than the fish-induced flow rate of 0.2m / s, and should be 0.35-0.73m / s.

[0158] Outlet flow rate: The outlet of the fish passage facility should maintain a certain flow rate so that the fish will not be affected in their normal migration after swimming out of the fish passage facility. Therefore, the outlet of the fish passage facility should not be arranged in a completely still water place, so that the fish cannot sense the flow rate and are easily lost. At the same time, the outlet position should not be too close to the discharge structure, and if the flow rate exceeds the critical flow rate of fish, the fish will be easily sucked into the sluice and taken downstream. According to the test results, the flow rate near the fishway outlet should not be still water, and 0.24~0.35m / s is appropriate.

[0159] Flow velocity of the main structure: The average flow velocity in the pool chamber is 0.24~0.67m / s, and try to ensure that there is at least 0.10~0.30m of low flow velocity area near the bottom wall for fish to live, and the flow velocity in this area is within 0.48m / s.

[0160] 3.4.4.2. Eel Road

[0161] So far, there is no specially built eel ladder in my country, so the relevant parameters are mainly referenced from related foreign projects. The practice of the eel ladder on the St. Lawrence River in the United States shows that: although research literature shows that eel fry have weak swimming ability, when the flow rate is less than 1.8m / s, eels can still swim upstream easily. Not only are they not washed away by the water, but they swim against the current or hold their position tightly. The Ontario Hydropower Station has shown through practice that the slope of the eel ladder can reach 40°.

[0162] In summary: Eels are fish with climbing habits. Although their swimming ability is measured to be small, the design should not be based on the measured swimming ability. According to foreign experience, eel paths can be designed with steep slopes, but staggered cylindrical tubes or piers should be designed at the bottom to provide a foothold for their climbing.

[0163] Summary: The main fish species of the third hub fishway should be downstream migratory fish (CA) flower eel, eel, and flower perch; upstream migratory fish (AN) seven-thread anchovy and flower mullet; historical freshwater fish red-eye trout and dace. Other fish species that can be taken into consideration include: spotted mullet, Chinese black mullet, spotted tongue goby, silverfish, tongue goby, semi-ridged Chinese fish [fish mang] and other estuarine fish; and Hepu mitten crab. The fish season of the third hub fishway is from November to September of the following year. The size range of the main fish species of the third hub fishway is 40 to 600 mm. The flow rate range of the fish hole / slit is 0.54~1.37m / s, and the average flow rate can be about 1.0m / s; the average flow rate in the pool chamber 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 it is preferably 0.35~0.73m / s; the outlet flow rate should not be still water, and it is preferably 0.24~0.35m / s. Eels are fish with climbing habits. Although the measured swimming ability is small, it should not be simply designed based on the measured swimming ability. The eel way can be designed as a steeper slope, but staggered cylindrical tubes or piers should be designed at the bottom to provide a fulcrum for climbing. In summary: Through the study of the swimming ability of the target fish passing through the fishway, the migratory ecological characteristics of the third hub fish passing objects are clarified:

[0164] The main fish species in the fishway are downstream migratory fish (CA) such as flower eel, eel, and flower perch, upstream migratory fish (AN) such as seven-thread anchovy and flower mullet, and historically distributed freshwater fish such as red-eye trout and dace; other fish species that are also considered are spotted mullet, Chinese black mullet, spotted tongue goby, silverfish, tongue goby, semi-ridged Chinese fish, and Hepu mitten crab. The fish passing season is from November to September of the following year. The main fish species passing through the vertical slot fishway are 40-600mm in size, and the fish species passing through the eel channel are 100-500mm in size.

[0165] By testing the swimming ability of the main fish species of the third hub fishway, such as sea bass, eel, red-eyed trout, and dace, as well as the fish currently distributed in this section of the river, the design indicators of the third hub fishway were comprehensively determined: the flow velocity range of the fish holes / slits of the vertical slot fishway is 0.54~1.37m / s, and the average flow velocity can be about 1.0m / s; the average flow velocity in the pool chamber is 0.24~0.67m / s; the inlet fish-attracting flow velocity should not be lower than the fish-sensing flow velocity of 0.2m / s, and should be 0.35~0.73m / s; the outlet flow velocity should not be still water, and should be 0.24~0.35m / s; eels are fish with climbing habits, and the eel way should not be simply designed based on the measured swimming ability, but can be designed as a steeper slope, but staggered cylindrical tubes or piers should be designed at the bottom to provide a fulcrum for their climbing.

[0166] Based on the evaluation of the swimming ability of fish in this application, the overall scheme of fishway 2 is obtained: the vertical slot fishway 23 and the eel way 24 are arranged on the shore side 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. The inlet of fishway 2 is arranged near the mainstream, and the eel way 24 and the vertical slot fishway 23 are arranged on the tailwater side of the power station 27 to meet the conditions of attracting and bringing in fish.

[0167] Fig.18 As shown, the structural parameters of the vertical slit fishway 23 are as follows: Width of the pool chamber 30: The width of the pool chamber 30 should be greater than 2 times the body length of the fish object. When there are multiple types of main fish objects, it should be determined according to the size of the largest fish object. Preferably, the specifications of the main fish objects are 4 to 60 cm, and the width of the fishway is selected to be 3 m, which can meet the requirements of fish passing and is relatively economical. Length of the pool chamber 30: The net length of the pool chamber 30 can be 1.2 to 1.5 times the width of the trough body. Preferably, the length of the pool chamber 30 is 3.6 m. Depth of the pool chamber 30: The water depth of the pool chamber 30 should meet the requirements of the body height of the fish object and the energy dissipation of the pool chamber 30. The minimum water depth should be greater than 2.0 times the body height of the largest fish object, and not less than 1.0 m. Preferably, the design water depth h is 1.0 to 3.36 m. Width of the vertical slit 31 of the fishway: The width of the vertical slit 31 of the partition 32 should not be less than 1 / 3 of the body length of the fish object. A vertical slit 31 type partition 32 is selected. Preferably, the width B of the vertical slit 31 is 0.45 m. 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 velocity coefficient of the partition 32, which is determined through hydraulic model tests and comprehensive analysis; I is the slope of the bottom slope of the fishway; 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 seam fishway inlet and outlet; m is the number of rest pools; 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; Q is the flow rate of the fishway, B is the width of the vertical seam 31; h is the water depth,

[0168] Furthermore, the overall structure of the fishway 2 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-eye 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.

[0169] 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 .

[0170] The part of the vertical slot fishway 23 located upstream of the eel way 2 is interspersed with water retaining structures, 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 arranged opposite to each other, and the guide plate 35 is smaller in width than the partition 32. A vertical slot 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, and the climbing matrix 20 includes a plurality of rows of pile structures 22, wherein each row is interspersed with at least two pile structures 22, and adjacent rows of the pile structures 22 are staggered with each other along the length direction of the migratory channel.

[0171] 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, compared with the bristle base, the pile structure 22 does not have bristles, so there is no debris blockage and it is easy to clean. In addition, the pile structure 22 can play a role in friction resistance, water flow concussion and diffusion to dissipate energy 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 8 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 are in 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. A preferred solution: the bottom diameter of the pile structure 22 is greater than the top diameter of the pile structure 22.

[0172] A preferred solution is that the pile structure 22 includes a plurality of forwardly arranged frustum piles, the lower portion of the frustum piles is connected to the bottom of the migratory channel, the top of the frustum piles is closed, and the height of the frustum piles is greater than the bottom diameter of the frustum piles.

[0173] A preferred solution: the pile structure 22 is a tubular structure, the lower part of the tubular structure is connected to the bottom of the migratory channel, the upper part of the tubular structure 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 are in arc transition; the height of the tubular structure is greater than the bottom diameter of the tubular structure, and the top diameter of the tubular structure is smaller than the bottom diameter of the tubular structure. The inner wall of the tubular structure can also assist eels in climbing, and a through hole 21 is provided on the upstream side of the tubular structure, which can provide better migratory conditions for small Hepu mitten crabs and eels, and at the same time, the tubular structure cooperates with the through hole 21 to better play the role of friction resistance along the way, water flow counteraction and diffusion to dissipate energy, and thus better improve the flow state and reduce the flow velocity of the vertical slit 31 through which 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 reciprocate and slide with the base.

[0174] The eel way 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 better meets the conditions for attracting and bringing in fish.

[0175] 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 protection scope of the present invention.

Claims

1. A method for evaluating fish swimming ability, characterized in that: The following steps are involved: S1. Confirm the canal cascade channelization level, divide the canal into sections based on the river conditions, plan to straighten the canal, arrange three-level cascade hubs on the canal, namely the first hub, the second hub and the third hub from upstream to downstream, and confirm the dredging excavation volume; S2. Determine the water demand of the river and the average water consumption over many years based on the functional positioning of the canal and the comprehensive utilization parameters of water resources; S3. Confirm the fish passing purpose at the third downstream hub; S4. Classify estuarine fish communities based on the interaction between freshwater runoff and saltwater intrusion; S5. Confirm the species of river-sea migratory fish and upstream migratory fish at the canal estuary and the ecological habits of estuarine fish, confirm the specifications of fish, and obtain fish that meet the requirements; S6. Determine the time period for fish passage in the fishway at the third hub based on the fish passage season and the fish passage period; S7. During the fish passage time period confirmed in step S6, the fish obtained in step S5 are tested for swimming ability at the third hub, and the swimming ability test results of different fish are obtained to clarify the migratory ecological characteristics of the fish passage objects at the third hub; S8. Determine the design indicators of the third hub fishway based on the migratory ecological characteristics of the fish passing through the third hub.

2. The method for evaluating the swimming ability of fish according to claim 1, characterized in that: In S5, river-sea migratory fish species include eel, flower eel and spotted sea bass; upstream migratory fish species include seven-thread anchovy and flower mullet.

3. The method for evaluating fish swimming ability according to claim 1, characterized in that: The portion of the canal located downstream of the third hub is a tidal river section.

4. The method for evaluating the swimming ability of fish according to claim 1, characterized in that: In step S7, an annular water tank is provided at the third hub, and a swimming area (12) is provided in the water tank, so that the fish swim in the swimming area (12), the water flow speed is manually controlled and set, and the swimming speed and swimming ability of the fish are calculated based on the water flow speed.

5. The method for evaluating the swimming ability of fish according to claim 4, characterized in that: The swimming ability of fish is tested to compare with that of fish of similar species and size, and the design flow rate of the fishway at the third hub is determined.

6. The method for evaluating the swimming ability of fish according to claim 5, characterized in that: The swimming ability of fish is tested by using an annular test water tank (1). The annular test water tank (1) comprises a strip-shaped elliptical annular flow channel (11). A swimming area (12) is arranged in a straight section area on one side of the strip-shaped elliptical annular flow channel (11). A flow stabilizer (13) is arranged at one end of the swimming area (12), and a grille (14) is arranged at the other end. A propeller flow meter (15) for discharging air in the longitudinal direction is arranged in a straight section area on the other side of the strip-shaped elliptical annular groove structure (11). The blades of the propeller flow meter (15) are driven to rotate by a motor (16), and the motor (16) is controlled by a frequency converter (17).

7. The method for evaluating the swimming ability of fish according to claim 6, characterized in that: The flow rate in the annular test water tank (1) is gradually increased by adjusting the working frequency of the motor, the flow rate in the water tank is tested when the motor frequency increases by a unit frequency, a standard curve is prepared, and a linear fitting is performed on the standard curve.

8. The method for evaluating the swimming ability of fish according to claim 7, characterized in that: The fitting equation of the flow velocity-frequency curve of the test annular test water tank (1) is: y=0.0474x-0.036, R2=0.999, wherein y is the flow velocity; x is the frequency, and R2 is the width of the strip elliptical annular flow channel.

9. The method for evaluating the swimming ability of fish according to claim 7, characterized in that: Test the fish's flow-taxis characteristics and flow-overcoming ability. Test indicators include induced flow velocity, critical swimming speed and breakthrough swimming speed.

10. The method for evaluating the swimming ability of fish according to claim 7, characterized in that: The induction flow rate test is as follows: Place more than 10 fish in a test annular test water tank (1), and gradually increase the flow rate until half of the test fish turn around to the countercurrent direction. At this time, the flow rate is the induced flow rate of the test fish group; The test fish is placed individually in the still water of the test annular test tank (1), and then the flow rate is gradually increased until the test fish turns to the countercurrent direction, at which time the flow rate is the induced flow rate of the individual test fish; and / or, The critical swimming speed test is as follows: The body length and weight of the tested fish are measured and the fish are placed in the swimming area (12) of the annular test water tank (1), and the initial flow velocity, flow velocity gradient and time gradient of the annular test water tank (1) are set; The dissolved oxygen and temperature were tested at regular intervals. When the fish reached the end grid of the swimming area and could not swim, the fish were removed from the swimming area (12) and the weight of the fish 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. and / or, The swimming ability of the knife-toothed anchovy is tested by analogy with that of the seven-thread anchovy.

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