Centralized overflow structure for automatically controlling water depth in fishway and construction method thereof

Abstract

The application discloses a centralized overflow structure for automatically controlling water depth in a fishway, wherein according to the habits of migratory fish in a river channel, the suitable water depth h and flow velocity v of the fish are determined, and the bottom slope i of the fishway is determined accordingly; the lowest and highest normal operation water levels of a reservoir area are defined as H1 and H2, only one fishway outlet is arranged in the reservoir, the bottom plate elevation of the fishway outlet is lower than H1 by h; the slope of the fishway bottom plate on the downstream side of the fishway outlet is i, and the slope is reduced along the axis of the fishway to a distance of more than (H2-H1) / i away from the fishway outlet, and then a flat-bottom overflow pool is arranged; the overflow pool water outlet is arranged on the side wall of the fishway, the overflow structure is arranged in a local area of the fishway, the water depth and flow velocity in the fishway are automatically adjusted, the single-outlet fishway can meet the needs of fish upstream migration, repeated scheduling of each gate in the case of multiple outlets is avoided, and the fishway operation and maintenance work is simplified; the overflow structure is arranged in a centralized manner, the arrangement is relatively easy, and the arrangement of the fishway and the hub is not affected.

Description

Technical Field

[0001] The present invention relates to the technical field of water conservancy and hydropower engineering, and in particular to a centralized overflow structure for automatically controlling the water depth in a fishway and a construction method thereof. Background Art

[0002] Water conservancy and hydropower projects often use dams to store water for purposes such as flood control, power generation, irrigation, and drinking water supply. Dams also block fish migration pathways, impacting the reproduction and survival of migratory fish. With increasing environmental protection requirements, fishways, which serve as pathways for fish to migrate upstream from the river channel downstream of the dam to the reservoir, have become a crucial component of water conservancy and hydropower projects. During project operation, the reservoir water level fluctuates depending on upstream water inflow and scheduling arrangements. With a fixed elevation at the upstream fishway outlet, the water depth and flow rate within the fishway may increase beyond the range that fish can adapt to, impacting their normal migration. To address this issue, fishways typically have multiple outlets at different elevations to accommodate reservoir water level fluctuations. These gates at the corresponding fishway outlets need to be opened and closed as the water level changes, leading to operational and maintenance difficulties.

[0003] Chinese invention patent No. 202310542393.8 provides an overflow method for automatically adjusting the water depth in a vertical slot fishway. This method utilizes multiple overflow sections connected in series. The overflow section at the head is connected to the fishway outlet chamber, and the overflow section at the tail is connected to the fishway entrance chamber. This automatically overflows excess flow and adjusts the water depth in the fishway. However, the arrangement of multiple overflow sections in series makes it difficult to arrange overflow facilities in situations where the fishway axis is long and the fishway needs to bend.

[0004] Based on the above situation, the present invention proposes a centralized overflow structure and construction method for automatically controlling the water depth in the fishway to effectively solve the above problems.

[0005] An overflow structure is set up in a local area of ​​the fishway to automatically adjust the water depth and flow rate in the fishway, so that a single exit of the fishway can meet the upstream needs of fish, simplifying the operation and maintenance of the fishway, which is of practical significance. Summary of the Invention

[0006] In order to solve the problems existing in the background technology, the present invention provides a centralized overflow structure and a construction method for automatically controlling the water depth in a fishway.

[0007] The present invention adopts the following technical solutions:

[0008] Based on the habits of migratory fish in the river channel, the suitable water depth h and flow velocity v for fish are determined, and the fishway bottom slope i is formulated accordingly; the lowest operating water level and the highest normal operating water level of the reservoir are defined as H1 and H2, and only one fishway outlet is set in the reservoir, and the fishway outlet elevation is h lower than H1; the slope of the fishway bottom plate on the downstream side of the fishway outlet is i, and it descends along the fishway axis to a distance greater than (H2-H1) / i from the fishway outlet. Then a flat-bottomed overflow pool is set up, and an overflow pool outlet is opened on the side wall of the fishway. The bottom elevation of the overflow pool outlet opening should be higher than the overflow pool bottom plate (H2-H1+h). The overflow pool length meets the maximum overflow demand, and the overflow water is discharged to the downstream of the dam; the fishway bottom plate rises sharply to the height of (H2-H1) at the end of the overflow pool, and the fishway bottom plate on the downstream side descends according to the slope i to the downstream inlet of the fishway.

[0009] Furthermore, since the bottom plate elevation of the fishway exit is h lower than H1, the fishway exit always has a certain water depth, which meets the conditions for fish to swim upstream.

[0010] Furthermore, when the reservoir water level is higher than H1, the overflow pool needs to overflow excess water. When the reservoir water level is H2, the maximum overflow flow Q is reached. The flow Q is the difference between the inflow and the outflow of the fishway. The length L of the overflow pool outlet along the fishway axis can be determined according to the following thin-wall weir flow formula:

[0011]

[0012] In the formula, m0 is the overflow coefficient. Considering that the overflow direction is perpendicular to the main flow direction, the coefficient k is added to the equation and is taken as 0.7-0.8; h1 is the water depth above the weir at the overflow pool outlet. To ensure that the overflow water flow has as little impact as possible on migratory fish, h1 is taken as 0.1m; h, H1, and H2 have the same meanings as described above.

[0013] Furthermore, the fishway outlet is provided with a fish-blocking net to prevent migratory fish from overflowing with the flow.

[0014] A method for constructing a centralized overflow structure for automatically controlling the water depth in a fishway comprises the following steps:

[0015] S1. Excavate the fishway foundation.

[0016] S2. Install fishway reinforcement and waterstops at structural joints, erect formwork, and pour fishway concrete. The fishway concrete includes concrete for the fishway foundation, side walls, and partitions. The fishway side walls and partitions have dense reinforcement and a dispersed structure, so pumped concrete can be poured.

[0017] S3. Before the fishway concrete is poured to the corresponding elevation, the drainage steel pipes should be buried in time and the galvanized steel mesh should be installed and fixed.

[0018] S4. Lay mortar and gravel on the bottom plate of the fish slope.

[0019] The present invention provides a centralized overflow structure and construction method for automatically controlling the water depth in a fishway: by setting an overflow structure in a local area of ​​the fishway, the water depth and flow rate in the fishway are automatically adjusted, so that a single outlet of the fishway can meet the upstreaming needs of fish, avoiding repeated scheduling of each gate in the case of multiple outlets, and simplifying the operation and maintenance of the fishway; the overflow structure is centrally arranged, the method is relatively easy to arrange, and it does not affect the layout of the fishway and the hub. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the planar layout of the present invention.

[0021] Figure 2 It is a longitudinal sectional view of the present invention.

[0022] Figure 3 It is a detailed plan view of the overflow pool section of the present invention.

[0023] Figure 4 It is a detailed longitudinal section of the overflow tank section of the present invention.

[0024] Figure 5 It is a cross-sectional view of the overflow tank section of the present invention.

[0025] The serial numbers marked in the figure represent the following sequence: 1. fishway outlet, 2. overflow pool, 3. overflow pool outlet, 4. fish screen, 5. drainage steel pipe, 6. fishway concrete partition, 7. gravel, 8. mortar, 9. slope change line, 10. vertical line. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Refer to the attached Figure 1-5 According to the habits of migratory fish in the river channel, the suitable water depth h and flow velocity v for fish are formulated, and the fishway bottom slope i is formulated accordingly; the lowest operating water level and the highest normal operating water level of the reservoir are defined as H1 and H2, and only one fishway outlet 1 is set in the reservoir, and the elevation of fishway outlet 1 is h lower than H1; the slope of the fishway bottom plate on the downstream side of the fishway outlet 1 is i, and it descends along the fishway axis to a distance of more than (H2-H1) / i from the fishway outlet 1, and then a flat-bottom overflow pool 2 is set, and an overflow pool outlet 3 is opened on the side wall of the fishway. The bottom elevation of the overflow pool outlet opening should be higher than the overflow pool bottom plate (H2-H1+h). The length of the overflow pool meets the maximum overflow demand, and the overflow water is discharged to the downstream of the dam; the fishway bottom plate at the end of the overflow pool rises sharply to the height of (H2-H1), and the downstream fishway bottom plate descends according to the slope i to the downstream inlet of the fishway.

[0028] Since the elevation of fishway exit 1 is h lower than H1, the water depth at fishway exit 1 is always certain, which meets the conditions for fish to swim upstream.

[0029] When the reservoir water level is higher than H1, the overflow pool needs to overflow excess water. When the reservoir water level is H2, the maximum overflow flow Q is reached. The flow Q is the difference between the inflow of the fishway outlet 1 and the flow of the fishway outlet 1. The length L of the overflow pool outlet 3 along the fishway axis can be determined according to the following thin-wall weir flow formula:

[0030]

[0031] In the formula, m0 is the overflow coefficient. Considering that the overflow direction is perpendicular to the main flow direction, the coefficient k is added to the equation and is taken as 0.7-0.8; h1 is the water depth above the weir at the overflow pool outlet 3. To ensure that the overflow water flow has as little impact as possible on migratory fish, h1 is taken as 0.1m; h, H1, and H2 have the same meanings as described above.

[0032] The fishway outlet 1 is provided with a fish-blocking net 4 to prevent migratory fish from overflowing with the flow.

[0033] A fishway concrete partition 6 is provided in the fishway.

[0034] Figure 2 Middle A: water surface line in the fishway when the upstream reservoir water level is H2;

[0035] Figure 2 Middle B: water surface line in the fishway when the upstream reservoir water level is H1;

[0036] Figure 3 The number 9 is the slope change line, which is the boundary line between two surfaces with different slopes.

[0037] Figure 3 The middle 10 is the vertical line.

[0038] A method for constructing a centralized overflow structure for automatically controlling the water depth in a fishway comprises the following steps:

[0039] S1. Excavate the fishway foundation according to the control points and technical requirements provided by the design and complete the foundation treatment.

[0040] S2. Fabricate and install the fishway reinforcement and structural joint waterstops according to design requirements. Formwork is erected and the fishway concrete partition 6 is poured. The fishway concrete includes the concrete for the fishway foundation, side walls, and partitions. The structural joint locations are determined according to the design drawings. The fishway side walls and partitions have dense reinforcement and a dispersed structure, allowing for pouring pumped concrete.

[0041] S3. Before the fishway concrete is poured to the corresponding elevation, the drainage steel pipe 5 should be buried in time and the galvanized steel mesh, i.e. the fish blocking net 4, should be installed and fixed.

[0042] S4. Lay mortar 8 and gravel 7 on the bottom plate of the fish slope.

[0043] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", "front end", "rear end", "two ends", "one end", "the other end", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they cannot be understood as limiting the present invention.

[0044] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A centralized overflow structure for automatically controlling the water depth in a fishway, characterized in that: Determine the suitable water depth h and flow velocity v for fish, and accordingly formulate the fishway bottom slope i; define the lowest operating water level and the highest normal operating water level of the reservoir as H1 and H2, and set only one fishway outlet in the reservoir, with the fishway outlet bottom plate elevation h lower than H1; the slope of the fishway bottom plate downstream of the fishway outlet is i, and it descends along the fishway axis to a distance greater than (H2-H1) / i from the fishway outlet. Then, set up a flat-bottomed overflow pool, and open an overflow pool outlet on the side wall of the fishway. The bottom elevation of the overflow pool outlet opening should be higher than the overflow pool bottom plate (H2-H1+h), and the overflow water is discharged to the downstream of the dam; the fishway bottom plate rises sharply to the height of (H2-H1) at the end of the overflow pool, and the downstream fishway bottom plate descends according to the slope i to the downstream inlet of the fishway.

2. A centralized overflow structure for automatically controlling the water depth in a fishway according to claim 1, characterized in that: The overflow pool is farther than (H2-H1) / i from the fishway outlet, and the bottom plate of the fishway at the end of the overflow pool rises steeply by a height of (H2-H1). When the reservoir water level is H1, the water depth at the fishway outlet is h, and the water depth gradually deepens downstream to (H2-H1+h) at the overflow pool. The water depth of the fishway on the downstream side of the overflow pool is h, and there is no excess water overflow. When the reservoir water level is H2, the water depth of the overflow pool and its upstream fishway is (H2-H1+h), and the water depth of the fishway on the downstream side of the overflow pool is h. Excess water is discharged downstream through the overflow pool. When the reservoir water level is between H1 and H2, the water depth on the upstream side of the overflow pool is between h and (H2-H1+h), and the water depth of the fishway on the downstream side of the overflow pool is h. Excess water is discharged downstream through the overflow pool.

3. The centralized overflow structure for automatically controlling the water depth in the fishway according to claim 1, characterized in that: When the reservoir water level is higher than H1, the overflow pool needs to overflow excess water. When the reservoir water level is H2, the maximum overflow flow Q is reached. The flow Q is the difference between the inflow at the fishway outlet and the outflow at the fishway inlet. The length L of the overflow pool outlet along the fishway axis can be determined according to the following thin-wall weir flow formula: In the formula, m0 is the overflow coefficient. Considering that the overflow direction is perpendicular to the main flow direction, the coefficient k is added to the equation and is taken as 0.7~0.8; h1 is the water depth above the weir at the overflow pool outlet, and the value of h1 is 0.1m; h is the water depth of the fishway on the downstream side of the overflow pool, H1 is the lowest operating water level of the reservoir area, and H2 is the highest normal operating water level.

4. The centralized overflow structure for automatically controlling the water depth in a fishway according to claim 1, characterized in that: The fishway exit is provided with a fish blocking net.

5. The construction method of a centralized overflow structure for automatically controlling the water depth in a fishway according to claim 1, characterized in that: The following steps are involved: S1. Excavation of fishway foundation; S2. Install the fishway reinforcement and waterstop at the structural joints, erect the formwork, and pour the fishway concrete. The fishway concrete includes the concrete for the fishway foundation, side walls, and partitions. S3. Before the concrete of the fishway is poured to the corresponding elevation, the drainage steel pipes should be buried and the fish intercepting nets should be installed and fixed; S4. Lay mortar and gravel on the bottom plate of the fish slope.

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