Water level variable amplitude self-adaptive composite partition plate type fishway

Abstract

According to the technical scheme, the water level variable amplitude self-adaptive composite partition plate type fishway comprises a flow passing groove, a water level variable amplitude self-adaptive composite partition plate type fishway body and a water level variable amplitude self-adaptive composite partition plate type fishway body, the side walls are arranged on the two sides of the overflowing groove respectively; the plurality of composite partition plates are mounted in the overflowing groove and comprise first partition plates and second partition plates; the first partition is located on the front side of the second partition in the water flow direction. The first partition plate is composed of two trapezoid symmetrical partition plates fixedly connected with the side walls and the overflowing groove, and the two trapezoid symmetrical partition plates are matched to form a trapezoid vertical seam overflowing structure with the narrow upper portion and the wide lower portion. The second partition plate is of a composite structure with a U-shaped plane and a trapezoidal vertical surface with a narrow upper part and a wide lower part, and is fixed at the center line of the overflowing groove; gaps exist between the two sides of the second partition plate and the side walls, and an inverted-trapezoid-shaped vertical seam overflowing structure with the wide upper portion and the narrow lower portion is formed. The self-adaptive water level amplitude variation capacity of the fishway is improved, a stable flow field beneficial to fish upstream tracing is formed, the fishes are better protected, and the blocking influence of a dam on drainage basin connectivity is relieved.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy engineering and environmental protection engineering, and in particular relates to a composite baffle-type fishway with adaptive water level amplitude variation. Background Art

[0002] For a long time, the construction of water conservancy projects has ensured the realization of various economic and social functions such as flood control, power generation, shipping and water supply, but engineering facilities such as dams have also had a profound impact on river ecosystems. The construction of large-scale dams has led to huge changes in the environmental characteristics of upstream and downstream, obstructed the transport of nutrients, fragmented river habitats, reduced aquatic biodiversity, and seriously affected the migration and ecological exchange of aquatic organisms such as fish. As an important ecological compensation measure to alleviate the barrier effect of dams, fishways have been used internationally for more than 300 years. The basic principle is to decompose the total water level difference between upstream and downstream into several smaller water level differences, reduce the flow rate of water, and thus provide fish with a suitable channel for upstream migration and migration.

[0003] Traditional fishway designs mainly include vertical slot, submerged hole and Daniel structures, among which the vertical slot fishway is widely used due to its simple construction and uniform structure. However, due to the complex terrain and climatic conditions of my country's major rivers, the water level changes greatly upstream and downstream of the fishway, and the existing vertical slot structure has obvious deficiencies in adapting to water level fluctuations.

[0004] It is specifically manifested in the following aspects:

[0005] 1. The change of the current section does not match

[0006] When the water level drops, the traditional vertical slot fishway has a fixed or evenly distributed flow cross-sectional area, which causes the cross-sectional area to decrease and the flow velocity to increase sharply. This causes the fish in the pool to encounter excessively high water velocity, which is not conducive to their upstream migration.

[0007] 2. Limited flow control capability

[0008] In the prior art, the flow cross-section is uniformly distributed in the longitudinal direction, making it difficult to effectively control the local flow velocity. This uniform flow field structure will interfere with the fish's perception of the mainstream direction and affect the normal migration behavior of the fish.

[0009] 3. Insufficient local energy dissipation

[0010] The vertical slit structure has a fixed hole width and cannot provide effective energy dissipation measures for different water depths and local flow states, resulting in a mismatch in the spatial distribution of the energy dissipation rate per unit water body, which further aggravates the emergence of local high-velocity areas in the fishway. Summary of the invention

[0011] The purpose of the present invention is to address the shortcomings of the above-mentioned background technology and to provide a composite baffle-type fishway with adaptive water level fluctuations, so as to improve the ability of the fishway to adapt to water level fluctuations, form a stable flow field that is conducive to fish upstream, better protect fish, and reduce the barrier effect of dams on the connectivity of the watershed.

[0012] The technical solution adopted by the present invention is: a composite baffle-type fishway with adaptive water level amplitude, comprising:

[0013] The flow channel has a uniform width along the entire length and a slope;

[0014] The side walls are respectively arranged on both sides of the flow channel;

[0015] A plurality of composite baffles installed in the flow channel, the composite baffles comprising a first baffle and a second baffle; the first baffle is located in front of the second baffle in the water flow direction;

[0016] The first baffle is composed of two trapezoidal plates that gradually widen from top to bottom and are fixed to the bottom and side walls of the flow channel; the two trapezoidal plates leave a vertical flow gap in the middle, which is narrow at the top and wide at the bottom, forming a flow structure that is narrow at the top and wide at the bottom;

[0017] The second baffle is an integral structure that is U-shaped in plane and trapezoidal in elevation, narrow at the top and wide at the bottom, and is fixed at the center line of the flow channel; vertical flow gaps are left between the left and right sides of the baffle and the side walls, corresponding to the central gap of the first baffle, forming a side channel that is wide at the top and narrow at the bottom;

[0018] The composite baffle makes the flow velocity in the flow channel unevenly distributed along the height direction, with higher velocity at the top and lower velocity at the bottom, forming a slow flow zone with a certain depth at the bottom, thereby reducing the increase in the flow velocity in the pool chamber and adapting to water level changes when the downstream water level drops.

[0019] In the above technical solution, the width of the top of the flow structure formed by the first partition is greater than 1.5 times the swing amplitude of the tail of the fish with the longest body length passing through the fishway.

[0020] In the above technical solution, the width of the bottom end of the flow structure formed by the second partition is greater than 1.5 times the swing amplitude of the tail of the fish with the longest body length passing through the fishway.

[0021] In the above technical solution, the width of the top of the flow-through structure formed by the first partition is greater than 0.2 meters.

[0022] In the above technical solution, the width of the bottom end of the flow structure formed by the second partition is greater than 0.2 meters.

[0023] In the above technical solution, the flow cross-sectional area S1 formed by the flow structure formed by any water level in the first baffle and the flow cross-sectional area S2 formed by the flow structure formed by the corresponding water level in the second baffle satisfy the following conditions: (1-a)S2≦S1≦(1+a)S2; where a is the coordination coefficient.

[0024] In the above technical scheme, the design process of the plane dimensions of the first baffle and the second baffle is as follows: in the water tank experiment, a water tank that is reduced in scale is constructed, and baffles are installed and water is passed according to the initial design dimensions; the water flow velocity at different measuring points is measured, or tracers are placed to observe whether the water flow is continuous through video monitoring, and the baffle size is adjusted according to the test results until the set flow field conditions are met.

[0025] In the above technical solution, the set flow field conditions include: the flow velocity in the water tank chamber is between 0.15 and 1.8 m / s, the water depth variation in the chamber is less than 0.3 m; there is no water drop or water jump, the streamlines are continuous, and there is no local strong water turbulence area.

[0026] In the above technical solution, the slope of the flow channel is a fixed angle, and the fixed angle ensures that the water flows smoothly along the channel within the design range.

[0027] In the above technical solution, the composite baffles are arranged at preset intervals along the longitudinal direction of the flow channel to form a plurality of local slow flow areas to meet the water flow environment requirements for the passage of different fish species.

[0028] The beneficial effects of the present invention are as follows: the present invention adopts a composite structure of a first baffle and a second baffle, so that the water flow in the fishway forms an uneven distribution of "large at the top and small at the bottom" along the height direction, thereby forming a slow flow area with a certain depth at the bottom of the fishway. This structural design can reduce the reduction of the flow cross-sectional area and the increase of the flow velocity when the downstream water level drops, improve the local flow state, and keep the change amplitude of the internal flow field relatively gentle, which is conducive to the safe passage of fish of different species and flow resistance. The present invention is provided with a composite energy dissipation baffle inside, so that the energy dissipation effect at the bottom is greater than that at the top, and the overall energy dissipation capacity can be enhanced and the flow velocity can be slowed down when the water level drops; the present invention has two mainstream migration channels, and fish are not easy to get lost in the fishway; the width of the slit is linearly widened from bottom to top, which is conducive to the passage of fish of different lengths and sizes. The present invention adjusts the flow field in the fishway through the composite baffle, so that the fishway can still maintain suitable hydraulic conditions under the condition of large water level fluctuation, and improves the shortcoming of the existing vertical slit fishway that has a weak ability to adapt to water level changes. In fishway projects, the use of this composite baffle-type fishway can enhance the adaptive ability of high head difference and long-distance fishways to water level fluctuations, improve the fish passage effect of the fishway, and better protect fish.

[0029] Furthermore, the top width of the flow structure formed by the first baffle of the present invention is greater than 1.5 times the swing amplitude of the fish's tail, ensuring that the width of the flow area is sufficient to meet the fish's swing and passing requirements, avoiding mechanical obstruction to the fish or local water flow turbulence caused by the narrow channel, thereby improving the passing rate.

[0030] Furthermore, the bottom width of the flow structure formed by the second baffle of the present invention is greater than 1.5 times the swing amplitude of the fish's tail, which also ensures that the bottom flow area has sufficient width to ensure that fish can pass smoothly in the lower flow rate area, while taking into account hydraulic stability and reducing the adverse effects of local high flow rates.

[0031] Furthermore, the flow width at the top of the first baffle of the present invention is greater than 0.2 meters, providing a clear minimum size standard to ensure that sufficient flow channel width can be formed under various working conditions, effectively dispersing water flow energy, reducing flow velocity peaks, and improving the environment for fish passage.

[0032] Furthermore, the flow width at the bottom end of the second baffle of the present invention is greater than 0.2 meters, which also ensures that the lower part of the fishway has at least a basic passage width, ensures the formation and stability of the low flow rate area, and provides safe passage conditions for fish.

[0033] Furthermore, the present invention achieves balance and coordination of water flow energy in different parts of the fishway by controlling the proportional relationship between the flow cross-sectional areas S1 and S2 formed by the first baffle and the second baffle (S2≦S1≦(1+a)S2), preventing rapid changes in water flow due to uneven local flow distribution, thereby improving the overall hydraulic regulation effect and the adaptability of fish passage.

[0034] Furthermore, the present invention uses a flume test to dynamically adjust and optimize the plane dimensions of the first baffle and the second baffle to ensure that the final design can achieve the preset flow field conditions. This method provides a practical and repeatable optimization process that can continuously correct the design parameters based on experimental data, thereby ensuring that the fishway has ideal hydraulic performance under actual working conditions.

[0035] Furthermore, the flow field conditions set by the present invention (flow rate in the pool chamber is 0.15-1.8 m / s, the water depth variation is less than 0.3 m, there is no water drop or water jump, the streamline is continuous, and there is no local strong water turbulence area) ensure that the fishway maintains a stable and continuous water flow environment during operation. This is not only conducive to fish perception and smooth upstreaming, but also avoids energy concentration and turbulence problems caused by sudden changes in local flow patterns.

[0036] Furthermore, the present invention provides a continuous and stable water flow channel by setting a flow channel with a fixed slope, so that the water flows smoothly along the channel. This design helps to control the flow velocity distribution in the fishway as a whole, reduce the impact on fish caused by sudden changes in water flow, and ensure the overall operation stability of the fishway.

[0037] Furthermore, the composite baffles of the present invention are arranged at preset intervals along the longitudinal direction of the flow channel to form multiple local slow flow areas. This layout design can provide multiple low-flow areas for rest and adaptation according to the differences in fish species and swimming abilities, improve the conditions for fish passage, and at the same time enhance the adaptability of the fishway to different water level changes, ensuring the efficient operation of the ecological channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a three-dimensional structural effect diagram of the present invention.

[0039] Figure 2 It is a schematic diagram of the structural longitudinal section of the present invention.

[0040] Figure 3 Schematic diagram of the plane dimensions of the embodiment.

[0041] Figure 4 Schematic diagram of the structure and dimensions of the first partition and the second partition in the embodiment.

[0042] Figure 5 It is the surface flow field distribution diagram of the pool chamber of the embodiment.

[0043] Figure 6 2. It is a flow field distribution diagram of the bottom layer of the pool chamber of the embodiment.

[0044] Figure 7 3 is a flow field distribution diagram of the first partition cross section in the embodiment.

[0045] Figure 8 3 is a flow field distribution diagram of the second partition cross section in the embodiment.

[0046] Fig. 9 It is a water depth distribution diagram along the embodiment.

[0047] Fig.10 2 is a diagram showing the average flow velocity distribution of the holes and slits along the embodiment.

[0048] Among them, 1 is the flow channel, 2 is the side wall, 3 is the first partition, and 4 is the second partition. DETAILED DESCRIPTION

[0049] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments to facilitate a clear understanding of the present invention, but they do not constitute a limitation on the present invention.

[0050] like Figure 1-4As shown, the present invention provides a composite baffle-type fishway with adaptive water level amplitude, comprising:

[0051] A flow channel 1, the width of which is uniform along the entire length and has a slope;

[0052] Side walls 2 are respectively arranged on both sides of the flow channel 1;

[0053] A plurality of composite baffles installed in the flow channel 1, wherein the composite baffles include a first baffle 3 and a second baffle 4; the first baffle 3 is located in front of the second baffle 4 in the water flow direction;

[0054] The first baffle 3 is composed of two vertical trapezoidal symmetrical baffles fixedly connected to the side wall 2 and the flow channel 1, which cooperate to form a trapezoidal vertical slot flow structure that is narrow at the top and wide at the bottom;

[0055] The second baffle 4 is a composite structure that is U-shaped in plane and trapezoidal in elevation, narrow at the top and wide at the bottom, and is fixed at the center line of the flow channel 1; there are gaps between the two sides of the second baffle 4 and the side wall 2, forming an inverted trapezoidal vertical slot flow structure that is wide at the top and narrow at the bottom;

[0056] The composite baffle makes the flow velocity in the flow channel 1 unevenly distributed along the height direction, with the flow velocity being larger at the top and smaller at the bottom, forming a slow flow zone with a certain depth at the bottom, thereby reducing the increase in the inlet flow velocity when the downstream water level drops and adapting to water level changes.

[0057] Specifically, the width a2 of the top of the flow structure formed by the first baffle 3 is greater than 1.5 times the tail swing of the longest fish passing through the fishway, and the width a1 of the bottom of the flow structure formed by the first baffle 3 is greater than a2, and the values ​​are set according to the specific fish passing requirements. Figure 4 As shown,

[0058] Specifically, the width of the bottom end b1 of the flow structure formed by the second baffle 4 is greater than 1.5 times the tail swing of the longest fish passing through the fishway, and the width b1 of the top end of the flow structure formed by the second baffle 4 is greater than b2, and the value is set according to the specific fish passing requirements. The top cross section of the second baffle 4 is a trapezoid with one side open, and the bottom cross section is a rectangle with the same side open.

[0059] Specifically, the width of the top of the flow structure formed by the first partition plate 3 is greater than 0.2 meters, and the width of the bottom of the flow structure formed by the second partition plate 4 is greater than 0.2 meters.

[0060] Preferably, the first partition is composed of two trapezoidal plates that gradually widen from top to bottom and are fixed to the bottom and side walls of the flow channel. The two trapezoidal plates leave a vertical flow gap in the middle, with a narrow top and a wide bottom, forming a "narrow top and wide bottom" flow structure.

[0061] Example dimensions for the first bulkhead are as follows:

[0062] Top gap width: about 0.20m;

[0063] Bottom gap width: about 0.80m;

[0064] Distance between the partition and the side wall: about 0.60m (can be adjusted according to the total width of the fishway and the size of the target fish);

[0065] Height of partition: matches the depth of the flow channel (about 3.0m in this embodiment).

[0066] The functional characteristics of the first partition are as follows:

[0067] The narrow upper and wide lower gap design can produce obvious flow velocity stratification when water flows through the baffle: the flow velocity at the upper part is relatively large, and the flow velocity at the lower part is relatively low;

[0068] When the downstream water level drops and the inlet flow velocity increases, the slow-flow area at the bottom can still maintain a certain depth, helping fish pass through the low-flow zone.

[0069] The second partition is an integral structure that is U-shaped in plane and trapezoidal in elevation, and is installed at the center line of the flow channel. Vertical flow gaps are left between the left and right sides of the partition and the side walls, corresponding to the central gap of the first partition, forming a side channel in the shape of an "inverted trapezoid" (wide at the top and narrow at the bottom). The second partition includes a partition body, and symmetrical wing plates are vertically arranged on the edges of both sides of the partition body. The partition body is a trapezoidal flat plate structure that is "narrow at the top and wide at the bottom", and the wing plates are triangular flat plate structures. The wing plates are distributed along both sides of the partition body.

[0070] Example dimensions for the second bulkhead are as follows:

[0071] Top width (partition body): about 0.50m;

[0072] Bottom width (partition body): about 1.10m;

[0073] Side gaps: for example, leave about 0.25m of flow passage at the bottom and about 0.55m at the top (designed according to the total width of the fishway and the needs of the target fish);

[0074] Partition height: also matches the depth of the flow channel.

[0075] The functional characteristics of the second partition are as follows:

[0076] Compared with the central flow form of the first baffle, the second baffle places the main structure on the center line, and diversion channels are formed on both sides; its "narrow at the top and wide at the bottom" main body makes the water flow in the middle relatively uniform, and the side gaps provide slow flow areas or rest areas under different water level conditions; the first and second baffles are arranged alternately, which can form different flow combinations along the fishway, enhancing the adaptability of the fishway to water level changes.

[0077] The central gap of the first baffle and the side gap of the second baffle appear alternately, so that the water flow forms different flow distributions in different sections, which can not only ensure smooth flow at high water levels, but also suppress excessive increase in flow rate at low water levels.

[0078] Both types of partitions are "narrow at the top and wide at the bottom" or "inverted trapezoidal" in shape, which can form a relatively stable low-flow area at the bottom, providing upstream channels or resting places for fish of different swimming abilities.

[0079] When the downstream water level drops, the flow velocity in the inlet section will inevitably increase. However, through the orderly arrangement of the above-mentioned composite baffle structure, the increase in the peak flow velocity can be effectively reduced, thereby improving the overall hydraulic stability and traffic efficiency of the fishway.

[0080] Specifically, the flow cross-sectional area S1 formed by the flow structure formed by any water level in the first baffle 3 and the flow cross-sectional area S2 formed by the flow structure formed by the corresponding water level in the second baffle 4 meet the following conditions: (1-a)S2≦S1≦(1+a)S2; where a is the coordination coefficient, which is 0.1-0.3, and the larger the scale of fishway construction, the smaller its value. Figure 4 As shown, the dark blue shaded part is S1 and the light yellow shaded part is S2.

[0081] Specifically, the design process of the plane dimensions of the first baffle 3 and the second baffle 4 is as follows: in the water tank experiment, a water tank that is reduced in scale is constructed, and baffles are installed and water is passed according to the initial design dimensions; the water flow velocity at different measuring points is measured, or tracers are placed to observe whether the water flow is continuous through video monitoring, and the baffle size is adjusted according to the test results until the set flow field conditions are met.

[0082] The set flow field conditions include: the flow velocity in the water tank chamber is between 0.15 and 1.8 m / s, the water depth variation in the tank chamber is less than 0.3 m; there is no water drop or water jump, the streamline is continuous, and there is no local strong water turbulence area, that is, the Froude number Fr is less than 1.7, and the energy dissipation rate per unit volume of the water body E is less than 200 W / m 3 ,The continuous flow was observed through manual viewing of video monitoring.

[0083] Specifically, the slope of the flow channel 1 is a fixed angle, and the fixed angle ensures that the water flows smoothly along the channel within the design range and is set according to the specific application scenario.

[0084] Specifically, the composite baffles are arranged at preset intervals along the longitudinal direction of the flow channel 1 to form a plurality of local slow flow areas to meet the water flow environment requirements for the passage of different fish species.

[0085] The following working conditions are proposed to perform calculation analysis on the embodiment to simulate the impact of the drop in the inlet water level. The calculation conditions are shown in Table 1.

[0086] Table 1 Composite baffle fishway simulation calculation conditions

[0087]

[0088] like Figure 5 and Figure 6 As shown, Figure 5 : The flow field distribution on the surface of the fishway in the embodiment. It can be seen that the flow width at the first baffle 3 on the surface is small, and the second baffle 4 plays a role in flow resistance and energy dissipation, but the water backflow is not significant.

[0089] Figure 6 The bottom flow field distribution of the fishway shows that the flow width at the first baffle 3 of the bottom layer is relatively large, the second baffle 4 plays a stronger role in flow resistance and energy dissipation, the water flow reflux is significant, and the bottom flow velocity is effectively reduced.

[0090] like Figure 7 As shown, they are respectively the flow field distribution simulations of the cross section of the first baffle 3 in the embodiment under three working conditions in turn. It can be seen that the flow velocity at the first baffle 3 is generally distributed as "large at the top and small at the bottom". The surface flow velocity in working condition 3 is about 1.5m / s, the bottom flow velocity is about 0.6m / s, the highest flow velocity point is distributed in the middle of the baffle, the highest flow velocity is about 1.9m / s, and the average flow velocity of the baffle section is 1.08m / s.

[0091] The cross-sectional velocity distribution law of working condition 2 is consistent with that of working condition 3, but as the downstream water level drops, the maximum velocity increases to about 2.4 m / s, and the average velocity of the first baffle 3 is 1.35 m / s.

[0092] In condition 1, the water level in the downstream drops significantly, the velocity in the inlet section increases significantly, and the average velocity in the first baffle 3 section is about 1.71 m / s. Such a "non-uniform" velocity distribution is conducive to the passage of fish of different species and different flow resistance. At the same time, when the average velocity in the section increases, the bottom velocity can still be maintained at a relatively low level, which is conducive to the passage of fish.

[0093] like Figure 8 As shown, they are respectively the flow field distribution simulations of the cross section of the second partition plate 4 in the embodiment under three working conditions in turn. It can be seen that the flow velocity at the second partition plate 4 is slightly smaller than that at the first partition plate 3, and the flow velocity distribution is relatively more uniform.

[0094] There are low flow rate areas in the pool chamber in front of and behind the second partition 4, which can provide a resting area for fish and are conducive to the upstream migration of fish.

[0095] like Fig. 9As shown, the water depth distribution along the composite baffle under the three calculation conditions in the embodiment. It can be seen that the water depth of the outlet section under the three conditions fluctuates around 2.98m, which is relatively stable, and the water depth along the way gradually decreases. When the inlet water level drops by 1m, the overall water surface line can still remain relatively stable. When the inlet water level drops by 2m, the water surface line of the inlet section drops more significantly.

[0096] like Fig.10 As shown, the distribution of the average flow velocity along the vertical seams of the composite partition under the three calculation conditions in the embodiment, it can be seen that the flow velocity along the outlet section and the middle section of the fishway is basically stable, and the flow velocity change mainly occurs in the inlet section.

[0097] In working conditions 1 and 2, as the water level drops, the average flow velocity of the inlet section increases continuously, reaching 1.41m / s and 2.26m / s respectively. Although it has increased compared with working condition 3, the amplitude is smaller than that of conventional fishways.

[0098] Through the calculation and analysis of the average flow velocity of the inlet vertical slit section under different working conditions in the embodiments, it can be seen that the inlet flow velocity of the composite baffle solution increases under the condition of downstream water level drop. When the downstream water level drops by 1.0m, the inlet flow velocity of the fishway 3 increases to 1.41m / s relative to the normal operating condition, an increase of 29%, while the flow velocity increase of the conventional vertical slit fishway should be 50%, and the reduction of the flow velocity by the composite baffle is 21%.

[0099] When the downstream water level drops by 2m, the flow velocity at the inlet of fishway 3 increases to 2.26m / s relative to the normal operating condition, an increase of 107.2%, while the increase in flow velocity of the conventional vertical slit fishway should be 200%. The reduction in flow velocity by using composite baffles is 92.8%.

[0100] Table 2 is a comparison of the calculation results of the energy dissipation effects of the composite baffle-type fishway in various working conditions in the embodiments, indicating that the present invention can greatly improve the ability of the fishway to adapt to water level changes.

[0101] Table 2 Comparison of energy dissipation effects of composite baffle fishway under various working conditions in the embodiments

[0102]

[0103] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A composite baffle fishway with adaptive water level amplitude, characterized by: include: The flow channel has a uniform width along the entire length and a slope; The side walls are respectively arranged on both sides of the flow channel; A plurality of composite baffles installed in the flow channel, the composite baffles comprising a first baffle and a second baffle; the first baffle is located in front of the second baffle in the water flow direction; The first baffle is composed of two trapezoidal plates that gradually widen from top to bottom and are fixed to the bottom and side walls of the flow channel; the two trapezoidal plates leave a vertical flow gap in the middle, which is narrow at the top and wide at the bottom, forming a flow structure that is narrow at the top and wide at the bottom; The second baffle is an integral structure that is U-shaped in plane and trapezoidal in elevation, narrow at the top and wide at the bottom, and is fixed at the center line of the flow channel; vertical flow gaps are left between the left and right sides of the baffle and the side walls, corresponding to the central gap of the first baffle, forming a side channel that is wide at the top and narrow at the bottom; The composite baffle makes the flow velocity in the flow channel unevenly distributed along the height direction, with higher velocity at the top and lower velocity at the bottom, forming a slow flow zone with a certain depth at the bottom, thereby reducing the increase in the inlet flow velocity and adapting to water level changes when the downstream water level drops.

2. The composite baffle-type fishway with adaptive water level amplitude according to claim 1 is characterized by: The width of the top of the flow structure formed by the first baffle is greater than 1.5 times the swing amplitude of the tail of the largest fish passing through the fishway.

3. The composite baffle fishway with adaptive water level amplitude according to claim 1 is characterized by: The width of the bottom end of the flow structure formed by the second partition is greater than 1.5 times the swing amplitude of the tail of the largest fish passing through the fishway.

4. The composite baffle fishway with adaptive water level amplitude according to claim 1 is characterized by: The width of the top of the flow-through structure formed by the first partition is greater than 0.2 meters.

5. The composite baffle fishway with adaptive water level amplitude according to claim 1 is characterized by: The width of the bottom end of the flow-through structure formed by the second partition is greater than 0.2 meters.

6. The composite baffle fishway with adaptive water level amplitude according to claim 1 is characterized by: The flow cross-sectional area S1 formed by the flow structure formed by any water level in the first baffle and the flow cross-sectional area S2 formed by the flow structure formed by the corresponding water level in the second baffle satisfy the following conditions: (1-a)S2≦S1≦(1+a)S2; where a is the coordination coefficient.

7. The composite baffle fishway with adaptive water level amplitude according to claim 1 is characterized by: The design process of the plane dimensions of the first baffle and the second baffle is as follows: in the water flume experiment, a water flume that is reduced in scale is constructed, and baffles are installed and water is passed according to the initial design dimensions; the water flow velocity at different measuring points is measured, or tracers are placed to observe whether the water flow is continuous through video monitoring, and the baffle dimensions are adjusted according to the test results until the set flow field conditions are met.

8. The composite baffle fishway with adaptive water level amplitude according to claim 7 is characterized by: The set flow field conditions include: the flow velocity in the water tank chamber is between 0.15 and 1.8 m / s, the water depth variation in the chamber is less than 0.3 m; there is no water drop or water jump, the streamline is continuous, and there is no local strong water turbulence area.

9. The composite baffle fishway with adaptive water level amplitude according to claim 1 is characterized in that: The slope of the flow channel is a fixed angle, and the fixed angle ensures that the water flows smoothly along the channel within the design range.

10. The composite baffle-type fishway with adaptive water level amplitude according to claim 1, characterized in that: The composite baffles are arranged at preset intervals along the longitudinal direction of the flow channel to form a plurality of local slow flow areas to meet the water flow environment requirements for the passage of different fish species.

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