Method for reconstructing vertical slot fishway into movable baffle fishway

Abstract

The application discloses a reconstruction method of a vertical slot fishway into a movable baffle fishway, which comprises the following steps: a) extending the fish inlet downstream; b) reconstructing the fish outlet into a transversely opening gate; and c) adding an automatically controlled energy dissipation baffle between pool rooms; when the defects of the original fishway are caused by the change of the upstream and downstream water levels, the steps of a) and b) need to be performed; when the defects of the original fishway are caused by the emergence of new low-swimming-speed fish species, the step of c) is performed; and when the original fishway has both of the above problems, the steps of a), b) and c) are simultaneously performed. The application has the advantages that the reconstruction method of the vertical slot fishway is provided; the reconstruction design method and the new body type of the fishway outlet; the reconstruction method of the fishway inlet; and the above method and body type have important effects on the improvement of the fish passing efficiency.

Description

Technical Field

[0001] This invention relates to a method for converting a vertical slotted fishway into a movable baffle fishway, belonging to the field of fish passage facility construction in water conservancy and hydropower projects. Background Technology

[0002] Fish passages are important facilities for connecting fish migration routes and are a key component of ecological protection and restoration technologies in water conservancy projects. The "Design Guidelines for Fish Passes in Water Conservancy and Hydropower Projects (SL 609-2013)" stipulates that when upstream water levels fluctuate significantly during the main fish passage season, multiple fish passage outlets at different locations and elevations should be provided. The Food and Agriculture Organization of the United Nations' publication, "Fish passes – Design, dimensions and monitoring," recommends that fish passage outlets should preferably be designed as vertical slits, and multiple outlets should be provided if water level fluctuations exceed 1 meter.

[0003] It is evident that the vertical slot fishway is a commonly used fishway design in engineering. For example... Figure 1 As shown, the fishway is a vertical slit running from top to bottom through the fish hole. Based on the complexity of the slit structure, it can be divided into general vertical slit type and vertical slit type with guide plates, etc. Based on the number of slits, it can be divided into double-sided and single-sided vertical slit types, etc. The vertical slit type mainly utilizes the diffusion and counter-current effects of water flow to dissipate energy, and its energy dissipation effect is more complete than that of general orifice type and overflow weir type, but its flow pattern is complex. The most famous example of a vertical slit fishway is the Hell's Gate fishway on the Fraser River in Canada, and this type is currently widely used abroad. In my country, single-sided guide vertical slit fishways include the Limin River Sluice Fishway, the Qililong Fishway in Zhejiang, the Yuxi Sluice Fishway in Anhui, and the Xijiang Fish Weir Fishway in Guangxi.

[0004] Generally, a well-designed and constructed vertical slotted fishway can meet the needs of fish passage. However, the following situations can affect its effectiveness:

[0005] The downstream topography has changed, affecting the downstream inlet water level;

[0006] In order to meet the needs of flood control, irrigation or power generation, the reservoir water level stay time during the fish passage period has been changed, which in turn affects the effective fish passage time.

[0007] Changes in inflow caused by climate change have resulted in water levels in the upstream and downstream areas not conforming to the original design.

[0008] The above three points can be summarized as follows: the difference in water head between upstream and downstream increases, and the actual flow velocity in the fishway exceeds the standard.

[0009] Changes in upstream and downstream water flow conditions, which alter the habitat conditions for fish, have led to changes in fish populations, resulting in the emergence of some fish species that require lower flow velocities to cross the dam. The fourth point can be summarized as the emergence of new fish passage demands, coupled with excessively high actual flow velocities in the existing fish passages.

[0010] Based on these changes, fish passages need to be rebuilt to meet the fish protection needs under the new conditions. However, existing technologies do not provide publicly available methods or techniques for rebuilding fish passages to address these various situations, nor is there any documentation explaining how to carry out such rebuilds. Existing fish passages with existing problems continue to operate under their original design conditions. During operation, because the original hydraulic boundary conditions cannot be achieved, their fish passage efficiency is significantly reduced or even completely fails to meet the requirements for fish passage. Summary of the Invention

[0011] Based on the above problems, this invention discloses a method for modifying a vertical slotted fishway into a dynamic baffle fishway, the purpose of which is to repair the problem of reduced fish passage capacity caused by the above four situations.

[0012] The present invention discloses a method for converting a vertical slotted fishway into a movable baffle fishway, wherein the vertical slotted fishway follows the following design process:

[0013] (1) Investigate the types of fish that need to pass through the fishway;

[0014] (2) Determine the design flow velocity of the fishway based on the type of fish passing through;

[0015] (3) Determine the upstream and downstream operating water levels and design head of the fish passage based on the basic design parameters of the dam and the types of fish that pass through it;

[0016] (4) Determine the size of the fish passage chamber based on the type of fish passing through;

[0017] (5) Based on the types of fish passing through in (1) and the design flow rate in (2), the type of partition that forms the vertical slit is initially obtained;

[0018] (6) Determine the head difference required for each stage of the pool based on the design flow rate in (2) and the baffle type in (5);

[0019] (7) Determine the fishway slope based on the length of the pool chamber determined in (4) and the head difference required for each level of the pool chamber determined in (6);

[0020] (8) Determine the number of partitions and the length of the fishway based on (3), (6) and (7);

[0021] (9) Adjust the type of partition, the size of the pool and the bottom slope of the fish passage through model tests or numerical simulation analysis.

[0022] When a fishway constructed according to the above process experiences changes in upstream and downstream water levels or the emergence of new low-speed fish species, this method can be used for reconstruction.

[0023] The present invention includes three main components: a) extending the fish inlet downstream; b) modifying the fish outlet into a horizontally opening gate; and c) adding automatically controllable energy dissipation baffles between the pool chambers.

[0024] If the defects in the original fishway are caused by changes in the upstream and downstream water levels, then modifications a) and b) are required.

[0025] When the defect in the original fish passage is due to the emergence of new low-speed fish species, method c) is used for improvement.

[0026] When the original fish passage has both of the above problems, methods a), b), and c) are used simultaneously for improvement.

[0027] The above-mentioned a) "the fish inlet extends downstream" refers to:

[0028] a1) Extend the fishway inlet downstream along the existing bottom slope, so that its farthest end reaches 1m below the current water surface to form a new fish inlet.

[0029] a2) Add a partition between the existing fish inlet and the new fish inlet. The type of partition should be the same as the original fishway partition. If the downstream extension distance is less than the total distance of 12 partitions, the spacing of the newly added partitions should be 0.85 times the original design spacing.

[0030] a3) If the downstream extension distance is greater than the total distance of 12 partitions, the newly added partitions will still use the original design spacing.

[0031] b) Converting the fish outlet into a horizontally opening gate refers to:

[0032] Due to climate change, the normal water level of the reservoir cannot reach the guaranteed water level when the fishway was designed. At this time, it is necessary to lower the elevation of the fishway outlet. After the outlet elevation is modified, the flat gate is replaced with a push gate.

[0033] The aforementioned push-pull door includes: a wing door, a door panel, a connecting main shaft, a fixed main shaft, a push-pull assembly, and a push-pull rod guide groove.

[0034] The width of the wing door mentioned above refers to the width of the narrow partition of the vertical slot fishway, and the width of the door panel mentioned above refers to the width of the wide partition of the vertical slot fishway.

[0035] The aforementioned door panel is on the same side as the wide partition of the first partition upstream of the fishway, and the wing door is on the same side as the narrow partition of the first partition.

[0036] A deflector plate is installed on the downstream side of the aforementioned door panel.

[0037] The water-facing surface of the aforementioned propeller plate is a concave arc surface, and the radius of the arc is the width of the fishway;

[0038] The spacing between the baffles is 1 / 8 of the fishway width;

[0039] The length of the deflector with the current is 1 / 8 of the fishway width;

[0040] The width of the water-facing side of the deflector plate is 1 / 8 of the fishway width;

[0041] The vertical height is 1 / 8 of the fishway design depth.

[0042] According to the inventor's experiments, the above dimensions allow the Lhasa schizothorax to stay at the fishway exit for a shorter time, reducing the average passage time of the Lhasa schizothorax by 2.5 hours.

[0043] c) Add automatically controlled energy dissipation baffles between the pool chambers.

[0044] Since not all fish species can be considered during the design phase, the fishway is generally selected based on the degree of threat it poses to protected fish species. After the fishway has been in operation for a period of time, it is found that fish species that did not previously need to cross the dam now require it. In this case, the fishway needs to be modified in a c) manner.

[0045] The purpose of the modification is to increase the energy dissipation steps of the fishway, thereby reducing the flow velocity at the vertical gaps and making it easier for fish with weak swimming ability to pass through; at the same time, it is also necessary to ensure that the fish that originally passed through the fishway are not disturbed by the water flow in the pool.

[0046] Therefore, this invention proposes an automatically controllable energy dissipation baffle that adjusts the angle of the energy dissipation baffle when facing different fish-passing objects, so that fish can quickly find an upward passage.

[0047] The aforementioned automatically controlled energy dissipation baffle includes: a longitudinal support frame for the baffle, a transverse support frame for the baffle, and a water flow adjustment plate;

[0048] The aforementioned longitudinal support frame for the baffle is fixed to the fishway partition.

[0049] The aforementioned longitudinal support frame and transverse support frame of the baffle are fixed together by a threaded lifting shaft;

[0050] The aforementioned water flow adjustment plate occupies 50% to 65% of the length of the transverse support frame of the baffle;

[0051] The aforementioned water flow adjustment plate consists of multiple louvered blades, with a maximum louvered blade opening angle of 37° and a single louvered blade height of 35cm. It is fixed to the horizontal support frame of the baffle via a pivot.

[0052] The aforementioned water flow adjustment plate has an approximately S-shaped pipe at its lowest point in the vertical direction;

[0053] The aforementioned threaded lifting shaft uses a wirelessly controlled servo motor to drive the crown gear for lifting.

[0054] The aforementioned louver blade cross-section curve consists of multiple straight lines and multiple curves connected together;

[0055] The aforementioned curves include: circular arcs and elliptical curves;

[0056] When the flow velocity inside the fishway pool exceeds the design value, the longitudinal support frame of the upper baffle descends into the water from the top of the fishway, and the transverse support frame of the baffle begins to block water. Due to the water flow velocity, the louvers of the water flow adjustment plate are partially lifted by the water flow. The water flow changes direction under the action of the louvers. Different flow velocities lift the louvers at different angles. The inventors observed on-site that: when the flow velocity is high, the louvers are lifted higher, and the degree of downward change in the flow velocity direction is lower; when the flow velocity is low, the louvers are lifted lower, and the degree of downward change in the flow velocity direction is higher. When the degree of downward change in the flow velocity direction is low, it attracts larger Lhasa nakedback and Schizothorax fish to approach and pass through the louvers. When the degree of downward change in the flow velocity direction is high, it attracts smaller Lhasa nakedback and Schizothorax fish to approach and pass through the louvers.

[0057] The beneficial effects of this invention are as follows:

[0058] 1) This invention proposes a method for modifying a vertical slotted fishway;

[0059] 2) This invention proposes a method for modifying the design of a fishway outlet and a new body shape;

[0060] 3) This invention proposes a method for modifying the fishway inlet;

[0061] 4) This invention proposes a design method and shape for a dynamic partition;

[0062] The above methods and body shapes play an important role in improving the passage efficiency of fish. Attached Figure Description

[0063] Figure 1 Schematic diagram of fishway layout in existing technology;

[0064] Figure 2 Schematic diagram showing the downstream extension of the fish inlet;

[0065] Figure 3 Schematic diagram of the fish outlet being rebuilt into a horizontally opening gate;

[0066] Figure 4 Schematic diagram of the shape of the deflector plate;

[0067] Figure 5 Schematic diagram of adding automatically controlled energy dissipation baffles between pool chambers;

[0068] Figure 6 A schematic diagram of an automatically controlled energy dissipation baffle fully open;

[0069] Figure 7 The fishway was modified using methods b) and c). Detailed Implementation

[0070] The present invention will now be further described with reference to the accompanying drawings. Example 1

[0071] After a certain fishway has been in operation for a period of time, due to severe downstream scouring, the downstream riverbed elevation has decreased, resulting in a drop in the downstream water level. The downstream inlet water level of the fishway can no longer meet the original design requirements; therefore, modifications a) and b) are required.

[0072] The basic design of the original fish passage follows the process described above:

[0073] (1) Investigate the types of fish that need to pass through the fishway;

[0074] (2) Determine the design flow velocity of the fishway based on the type of fish passing through;

[0075] (3) Determine the upstream and downstream operating water levels and design head of the fish passage based on the basic design parameters of the dam and the types of fish that pass through it;

[0076] (4) Determine the size of the fish passage chamber based on the type of fish passing through;

[0077] (5) Based on the types of fish passing through in (1) and the design flow rate in (2), the type of partition that forms the vertical slit is initially obtained;

[0078] (6) Determine the head difference required for each stage of the pool based on the design flow rate in (2) and the baffle type in (5);

[0079] (7) Determine the fishway slope based on the length of the pool chamber determined in (4) and the head difference required for each level of the pool chamber determined in (6);

[0080] (8) Determine the number of partitions and the length of the fishway based on (3), (6) and (7);

[0081] (9) Adjust the type of partition, the size of the pool and the bottom slope of the fish passage through model tests or numerical simulation analysis.

[0082] The fishway constructed according to the above process experienced a drop in downstream water level during its operation, and this method was used for reconstruction.

[0083] This embodiment involves a) modifying the fish inlet to extend downstream;

[0084] The above-mentioned a) "the fish inlet extends downstream" refers to:

[0085] a1) Extend the fishway inlet 45m downstream along the existing bottom slope, so that its farthest end reaches 1m below the current water surface to form a new fish inlet.

[0086] a2) Add a partition between the existing fish inlet and the new fish inlet. The type of partition is the same as the original fishway partition design. The original partition spacing is 4.5m. Extending it by 45m means the extension distance is 10 partitions of the original design, which is less than the total distance of 54m for 12 partitions. Therefore, the spacing of the newly added partition is 0.85 times the original design spacing. The newly added partition spacing is 4.5 × 0.85 = 3.825m. A total of 45 ÷ 3.825 = 11.76 ≈ 12 partitions are needed. At this time, the length of the fishway is extended to the position of the 12th partition, that is, the total length is extended to 45.9m.

[0087] The final modified form of the fishway is as follows: extending 45.9m downstream from the existing fishway inlet, reaching a maximum depth of 1.2m below the current water surface, and adding 12 baffles within the 45.9m range, with the baffles having the same shape as the original baffles. Example 2

[0088] Due to climate change, the normal water level of a reservoir cannot reach the guaranteed rate level of 42.3m for the designed fishway, resulting in no inflow into the fishway. Therefore, it is necessary to lower the outlet elevation of the fishway and, after modifying the outlet elevation, replace the flat gate with a push gate. The original design bottom slope of the fishway was i=2%. Lowering the outlet elevation by 5m requires removing the baffles within the upstream 25m length of the fishway. After removal, the bottom slope within this 25m section will be 0, and the flat gate will be replaced with a push gate.

[0089] The aforementioned push-pull door includes: a wing door 11, a door panel 12, a connecting main shaft 13, a fixed main shaft 14, a push-pull assembly 15, and a push-pull rod guide groove 16.

[0090] The width of the aforementioned wing door 11 is the width of the narrow partition of the vertical slit fishway, and the width of the aforementioned door panel 12 is the width of the wide partition of the vertical slit fishway.

[0091] The aforementioned door panel 12 is on the same side as the wide partition of the first partition upstream of the fishway, and the wing door 11 is on the same side as the narrow partition of the first partition.

[0092] Multiple deflector plates 121 are provided on the downstream side of the aforementioned door panel 12.

[0093] The water-facing surface of the aforementioned flow deflector 121 is a concave arc surface, and the radius of the arc is the width of the fishway. In this embodiment, the width of the fishway is 2m.

[0094] The spacing between the baffles is 1 / 8 of the fishway width, which is 25cm in this embodiment;

[0095] The length of the diversion plate downstream of the water flow is 1 / 8 of the fishway width, which is 25cm in this embodiment;

[0096] The width of the water-facing surface of the deflector is 1 / 8 of the fishway width, which is 25cm in this embodiment;

[0097] The vertical height is 1 / 8 of the fishway design water depth. In this embodiment, the design water depth is 1.6m, so its vertical height is 0.2m.

[0098] According to the inventor's experiments, the above dimensions allow the Lhasa schizothorax to stay at the fishway exit for a shorter time, reducing the average passage time of the Lhasa schizothorax by 2.5 hours.

[0099] The modified fishway meets the upstream water level requirements. Example 3

[0100] In a certain fishway, the fish species *Schizothorax heterodon* was not included in the design during the design phase. However, after the fishway was built, it was found that the population of *Schizothorax heterodon* was severely affected and required protection by a dam. In this case, the fishway needs to be modified in category c).

[0101] The purpose of the modification is to increase the energy dissipation steps of the fishway, thereby reducing the flow velocity at the vertical gaps and making it easier for fish with weak swimming ability to pass through; at the same time, it is also necessary to ensure that the fish that originally passed through the fishway are not disturbed by the water flow in the pool.

[0102] Therefore, the embodiment proposes an automatically controllable energy dissipation baffle that adjusts the angle of the energy dissipation baffle when facing different fish passing objects, so that fish can quickly find an upward passage.

[0103] The aforementioned automatic control energy dissipation baffle includes: a longitudinal support frame 21 for the baffle, a transverse support frame 22 for the baffle, and a water flow adjustment plate 23;

[0104] The aforementioned longitudinal support frame 21 of the baffle is fixed to the fishway partition;

[0105] The aforementioned longitudinal support frame 21 and transverse support frame 22 of the baffle are fixed together by a threaded lifting shaft 24;

[0106] The aforementioned water flow adjustment plate 23 occupies 50%~65% of the length of the transverse support frame 22 of the baffle;

[0107] The aforementioned water flow adjustment plate 23 consists of multiple louvered blades, with a maximum opening angle of 37° and a single louvered blade height of 35cm. It is fixed to the horizontal support frame 22 of the baffle via a pivot.

[0108] The aforementioned water flow adjustment plate 23 has an approximately S-shaped pipe at its lowest point in the height direction;

[0109] The aforementioned threaded lifting shaft 24 uses a wirelessly controlled servo motor 241 to drive the crown gear for lifting.

[0110] The aforementioned louver blade cross-section curve consists of multiple straight lines and multiple curves connected together;

[0111] The aforementioned curves include: circular arcs and elliptical curves;

[0112] The elliptic curve mentioned above is the head-top water curve, and its equation is: ;

[0113] Connect the upper straight line segment;

[0114] Connect the following line segments sequentially below:

[0115] Circular arc radius 7, central angle 66°; circular arc radius 5, central angle 90°; circular arc radius 16, central angle 33°; circular arc radius 8, central angle 47°; straight line segment;

[0116] When it is necessary to reduce the flow rate inside the fishway pool, the servo motor 241 drives the crown gear, causing the threaded lifting shaft 24 to descend, and the baffle horizontal support frame 22 falls into the bottom of the fishway to begin blocking water.

Claims

1. A method for modifying a vertical slot fishway into a flip bucket fishway, characterized by: The vertical slit fishway follows the following design process: (1) Investigate the fish species that need to pass through the fishway; (2) Determine the design flow rate of the fishway according to the fish species; (3) Determine the upstream and downstream operating water levels and design water head of the fishway according to the basic design parameters of the dam and the fish species; (4) Determine the size of the pool chamber according to the fish species; (5) Preliminarily obtain the type of the vertical slit according to the fish species in (1) and the design flow rate in (2); (6) Determine the water head difference required by each pool chamber according to the design flow rate in (2) and the type of the vertical slit in (5); (7) Determine the fishway slope according to the pool chamber length determined in (4) and the water head difference required by each pool chamber determined in (6); (8) Determine the number of baffles and the length of the fishway according to (3), (6) and (7); (9) Model test or numerical simulation calculation and analysis to adjust the type of the baffle, the size of the pool chamber and the fishway bottom slope; The method comprises the following three contents: a) The fish inlet extends downstream; b) The fish outlet is rebuilt as a transverse opening gate; c) Automatic control energy dissipation baffles are added between the pool chambers; When the defects of the original fishway are caused by changes in the upstream and downstream water levels, the fish inlet extends downstream and the fish outlet is rebuilt as a transverse opening gate; When the defects of the original fishway are caused by the appearance of new low swimming speed fish species, the automatic control energy dissipation baffles are added between the pool chambers; When the original fishway has both of the above problems, the methods of a), b) and c) are used for improvement; The a) fish inlet extending downstream refers to: a1) The fish inlet of the fishway is extended downstream along the original bottom slope, so that the farthest end reaches 1m below the current water surface to form a new fish inlet; a2) A baffle is added between the original fish inlet and the new fish inlet, and the type of the baffle is consistent with the original fishway design baffle. If the downstream extension distance is less than 12 times the total distance of the baffles, the spacing of the newly added baffles is 0.85 times the original design spacing; a3) If the downstream extension distance is greater than 12 times the total distance of the baffles, the newly added baffles still use the original design spacing; The b) fish outlet rebuilt as a transverse opening gate refers to: Due to climate change, the normal reservoir water level cannot reach the guaranteed water level of the design fishway. At this time, the fishway outlet elevation needs to be lowered. After modifying the outlet elevation, the flat door is changed to a push door; The push door comprises a wing door, a door plate, a connecting main shaft, a fixed main shaft, a push assembly and a push rod guide groove; The width of the wing door is the width of the narrow baffle of the vertical slit fishway, and the width of the door plate is the width of the wide baffle of the vertical slit fishway; The door plate is on the same side as the wide baffle of the first baffle upstream of the fishway, and the wing door is on the same side as the narrow baffle of the first baffle; The downstream side of the door plate is provided with a flip plate, The water-facing surface of the flip plate is a circular arc concave surface, and the circular arc radius is the width of the fishway; The flip plate spacing is 1 / 8 of the width of the fishway; The flip plate length along the water flow is 1 / 8 of the width of the fishway; The flip plate water-facing surface width is 1 / 8 of the width of the fishway; The vertical direction height is 1 / 8 of the design water depth of the fishway.

2. The reconstruction method of claim 1, wherein The c) inter-pool chamber energy dissipation baffle with automatic control refers to that after the fishway operates for a period of time, it is found that the fish originally not needing to pass the dam becomes to need to pass the dam, at which time the fishway needs to be modified in the c) type, i.e. adding the inter-pool chamber energy dissipation baffle with automatic control.

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