Used for fish passes in low head dams with high sediment content and large head fluctuations

Abstract

The present invention provides a low-head dam fishway for high-sediment content and large head fluctuation, comprising an upstream water inlet section, a sedimentation tank section, a simulated natural fishway, a conventional fishway and a downstream water outlet section, wherein the sedimentation tank section is trapezoidal, and its long sides are respectively connected to the upstream water inlet section and the simulated natural fishway in a straight line, and its short sides are connected to the conventional fishway; the simulated natural fishway is a slope section, in which a first upstream gate, a plurality of baffles and a first downstream gate are arranged; the downstream water outlet section is respectively connected to the simulated natural fishway and the conventional fishway, and a fish guide fence is arranged at the confluence; the conventional fishway is provided with a second upstream gate and a sand retaining plate at the connection with the sedimentation tank section, and a second downstream gate is provided at the connection with the downstream water outlet section, and a plurality of partitions are arranged inside. The benefits of the present invention are: it achieves the goals of reducing the water sediment content of the fishway, ensuring the long-term reliable operation of the fishway through multi-mode operation, improving the attractiveness of the fishway inlet, and taking into account the discharge of ecological flow.

Description

Technical Field

[0001] The invention belongs to the technical field of river connectivity restoration engineering, and in particular relates to a low-head dam fishway for areas with high sediment content and large head fluctuations. Background Art

[0002] Most of the life activities of fish, such as reproduction, foraging and overwintering, need to be completed through migration in order to find the most suitable habitat at different stages. Fish habitat is an important part of the river ecosystem, but hydraulic structures in rivers block the connectivity of rivers, prevent fish from migrating upstream, and to a certain extent destroy fish habitats, causing a decline in the total amount of fish resources. In order to alleviate the adverse effects of the construction of hydraulic structures on the river ecosystem, the construction of fish passage facilities has gradually become an important means to restore river connectivity, and fishways have become the main fish passage facilities in my country due to their simple structure and mature technology.

[0003] At present, fishways are usually built on dams of a certain scale. The reservoir capacity of such dams has a certain regulation capacity, and the water level in the reservoir area can ensure a stable flow during the operation of the fishway, with less sediment in the water flow. During the design process, multiple water inlets at different elevations are usually set up to adapt to the changes in the water level in the reservoir area in different seasons. The water replenishment at the fishway inlet can also be achieved by directly diverting water from the reservoir area using pressure pipes. In addition, during the construction process of such dams, ecological flow guarantee plans are usually considered more comprehensively, providing a more ideal basic guarantee for the design of fishways.

[0004] With the deepening of ecological protection construction, ecological management work for small hydropower stations in mountainous areas with high sediment content and large head fluctuations has been gradually carried out. Unlike large dams with a certain regulating reservoir capacity, small hydropower stations in mountainous areas are mostly diversion-type power stations. The upstream flow is very unstable. The power stations basically have no water storage during the dry season. The water level of the reservoir is high during the flood season. The sediment content is high all year round, and the reservoir area is seriously silted up, with basically no storage capacity. When designing fishways for low-head dams with high sediment content and large head fluctuations in mountainous areas, it is often necessary to overcome many special factors, including the following difficulties:

[0005] (1) The water level in the reservoir area fluctuates greatly, and the minimum operating water level of the fishway cannot be guaranteed. During the flood season, the flow rate in the river channel is large, which can guarantee the operating water level of the fishway. However, as the flood season ends, the flow rate in the river channel will drop significantly. When the basin enters the dry season, the water depth in the reservoir area is not much different from the water depth in the river channel, and the minimum operating water level of the fishway cannot be guaranteed, which seriously affects the operation period of the fishway.

[0006] (2) The sediment content is high all year round, the fishway is seriously silted up, and the operating cost is high. There are obvious mainstream areas and slow-flow areas inside the fishway. The high sediment content of the water entering the fishway all year round will cause siltation in the slow-flow area that is difficult to alleviate. When the fishway has been in operation for a long time, the siltation in the fishway is serious, and the slow-flow area for upstream migratory fish to rest almost no longer exists, which seriously affects the normal operation of the fishway and greatly reduces the success rate of fish upstream migration. In order to ensure the normal operation of the fishway, frequent dredging is required inside, which greatly reduces the operation time of the fishway and increases the operating cost.

[0007] (3) The fishway has a single operation mode and low reliability. When silt removal is carried out during the operation of the fishway, the migratory fish will be blocked again due to the lack of a backup channel. The operation time of the fishway is reduced and a reliable upstream migration channel cannot be provided for migratory fish.

[0008] (4) Ecological flow cannot be guaranteed, and it is difficult to replenish water at the fishway inlet. In order to maximize profits, small hydropower owners usually divert most of the water in the river channel for power generation. The ecological flow cannot be effectively guaranteed. When the river is in the dry season, there is basically no ecological flow in the original river channel. The long distance of reduced water flow between the dam site and the tailwater outlet of the water diversion power station will seriously hinder the upstream migratory fish, making the construction of the fishway project lose its original meaning. In addition, since the flow rate at the fishway inlet is usually small, in order to increase the attraction of the inlet to fish, it is usually necessary to take water replenishment measures at the fishway inlet. However, factors such as the instability of the water level of the reservoir of the small hydropower station and the severity of siltation will seriously hinder the design of fishway water replenishment measures, making it difficult to replenish water at the fishway inlet. Summary of the invention

[0009] In view of the above-mentioned defects, the technical problem to be solved by the present invention is to provide a low-head dam fishway for use in areas with high sediment content and large head fluctuations, so as to achieve the goals of reducing the sediment content entering the fishway, ensuring long-term reliable operation of the fishway through multi-mode operation, increasing the attractiveness of the fishway inlet, and taking into account the ecological flow discharge.

[0010] The present invention provides a low-head dam fishway for use with high sediment content and large head fluctuations, which is arranged on a side away from a water diversion gate and comprises an upstream water inlet section, a sedimentation tank section, a simulated natural fishway, a conventional fishway and a downstream water outlet section, wherein the upstream water inlet section is provided with a water inlet gate and a water flow guide device for changing the direction of water flow in sequence from the outside to the inside; the sedimentation tank section is located between the upstream water inlet section and the simulated natural fishway, and is in a trapezoidal shape, with its long sides respectively connected to the upstream water inlet section and the simulated natural fishway in a straight line, and its The short side is connected to the conventional fishway; the simulated natural fishway is a slope section, in which a first upstream gate, a plurality of baffle bodies and a first downstream gate are arranged in sequence, and the plurality of baffle bodies are arranged in a staggered manner; the downstream outlet section is respectively connected to the simulated natural fishway and the conventional fishway, and a fish guide fence is provided at the junction; the conventional fishway is a slope section, and a second upstream gate and a sand retaining plate are provided at the connection with the sedimentation tank section, and a second downstream gate is provided at the connection with the downstream outlet section, and a plurality of partitions are provided inside.

[0011] Preferably, the water flow guiding device comprises a plurality of guide plates arranged at intervals, and the center distance between two adjacent guide plates is not less than 30 cm.

[0012] Preferably, the slope of the simulated natural fishway is no more than 10%.

[0013] Preferably, the height of the bluff body is 50 cm, and the distance between two adjacent bluff bodies is 30-50 cm.

[0014] Preferably, the height of the sand barrier is no more than 50 cm.

[0015] Preferably, the angle between the downstream outlet section and the mainstream of the river channel is less than 45°.

[0016] Preferably, the fish guide fence is a grid structure, and the maximum width of the grid is not greater than 30 mm.

[0017] Preferably, the upstream water inlet section, the sedimentation tank section and the downstream water outlet section are all flat slope sections.

[0018] The present invention is beneficial in that:

[0019] (1) It has multiple fishway operation modes and is highly adaptable to water level changes, effectively improving reliability.

[0020] (2) The fishway has multiple functions, taking into account both ecological flow discharge and imported water replenishment.

[0021] (3) Special sedimentation treatment can reduce the amount of sand entering the fishway and reduce siltation in the fishway. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1It is a structural schematic diagram of a low-head dam fishway of the present invention;

[0023] Figure 2 It is a cross-section diagram that imitates a natural fishway;

[0024] Figure 3 It is a schematic diagram of the installation of the bluff body in the simulated natural fishway;

[0025] Figure 4 It is a schematic diagram of the structure of the water flow guiding device;

[0026] Figure 5 It is a schematic diagram of the structure of the fish guide fence;

[0027] Component number description:

[0028] 1 Upstream water inlet section

[0029] 11 Inlet gate

[0030] 12 Water flow guide device

[0031] 121 Guide plate

[0032] 2 Sand settling tank section

[0033] 3. Natural fishway

[0034] 31 First upstream gate

[0035] 32 First downstream gate

[0036] 33 Baffle

[0037] 4 Conventional fishways

[0038] 41 Second upstream gate

[0039] 42 Second downstream gate

[0040] 43 Partition

[0041] 44 sand retaining board

[0042] 5 Downstream outlet section

[0043] 51 Fish screen

[0044] 6. Barrage

[0045] 7. Sluice Gate DETAILED DESCRIPTION

[0046] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0047] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0048] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0050] like Figure 1 As shown, the present invention provides a low-head dam fishway for high sediment content and large head fluctuations. The fishway is arranged on the side away from the water diversion gate 7, and includes an upstream water inlet section 1, a sedimentation tank section 2, a simulated natural fishway 3, a conventional fishway 4 and a downstream water outlet section 5. Among them, the upstream water inlet section 1 is a flat slope section, in which an inlet gate 11 and a water flow guide device 12 are arranged in sequence from the outside to the inside. The inlet gate 11 is used to block the water in the upstream river from entering the fishway project during the maintenance period, and the water flow guide device 12 is used to change the direction of the water flow entering the sedimentation tank section 2. Its specific structure is as shown in FIG. Figure 4 As shown, it includes a plurality of guide plates 121 arranged at intervals, and the center distance between two adjacent guide plates 121 is not less than 30 cm.

[0051] The sedimentation tank section 2 is a flat slope section, arranged on the downstream side of the upstream water inlet section 1, between the upstream water inlet section 1 and the simulated natural fishway 3, and is a trapezoidal structure. Its long sides are directly connected to the upstream water inlet section 1 and the simulated natural fishway 3 respectively, and the short sides protrude outward relative to the upstream water inlet section 1 and are vertically connected to the conventional fishway 4. Most of the water flow in the sedimentation tank section 2 will directly enter the simulated natural fishway 3 from the long sides, where the flow velocity is higher and the water flow has a stronger sand-carrying capacity; while the water flow section on the short sides is enlarged, and the water flow velocity on this side is low, so the flow entering the conventional fishway 4 is small, and the sand-carrying capacity is weak, which can achieve the purpose of sedimentation. Since the water flow entering the simulated natural channel 3 is much larger than the water flow entering the conventional fishway 4, the simulated natural channel 3 can be used as a water replenishment channel when the conventional fishway 4 operates normally.

[0052] like Figure 1 and Figure 2 As shown, the simulated natural fishway 3 is a slope section, and its slope should not be greater than 10%. It can be determined according to the project site to adopt a straight line through the dam 6 or a curved arrangement to bypass the dam 6. A first upstream gate 31, a plurality of baffles 33 and a first downstream gate 32 are arranged in sequence. The first upstream gate 31 is a working and maintenance gate, which is used to control the water flow entering the simulated natural fishway 3. The first downstream gate 32 is a maintenance gate, which is used to block the water in the downstream river from entering the simulated natural fishway 3 during the maintenance period. The plurality of baffles 33 are arranged in a staggered manner. The "staggered arrangement" here specifically refers to the following. Figure 3 As shown, the number of bluff bodies 33 in two adjacent rows is different, and the shape of the bluff body 33 can be selected according to the engineering situation, specifically a semi-cylindrical shape. The water flow width (i.e., spacing) between two adjacent bluff bodies 33 in the same row should be between 30 cm and 50 cm, and the height of each bluff body 33 is 50 cm.

[0053] like Figure 1 As shown, the downstream outlet section 5 is a flat slope section, which is connected to the ends of the simulated natural fishway 3 and the conventional fishway 4 respectively, and has the same elevation as the bottom plate of the ends of the simulated natural fishway 3 and the conventional fishway 4. A fish guide fence 51 is provided at the junction of the three. The fish guide fence 51 is a grid-like structure, the maximum width of which is no more than 30 mm, and is arranged obliquely at the downstream end of the simulated natural fishway 3 to guide fish into the conventional fishway 4. In order to improve the fish attracting effect, the angle between the downstream outlet section 5 and the mainstream of the river should be less than 45°.

[0054] The conventional fishway 4 is a slope section, the water inlet section of which is connected to the sedimentation tank section 2 and is arranged with a 90° bend. At the connection between the water inlet section and the sedimentation tank section 2, the bottom plates of the two sections have the same elevation, and a second upstream gate 41 and a Figure 2 The sand retaining plate 44 shown in the figure is provided with a second downstream gate 42 at the connection with the downstream outlet section 5, and a plurality of partitions 43 are provided inside. The second upstream gate 41 and the second downstream gate 42 are both maintenance gates, which are used to block the water in the sedimentation tank section 2 and the downstream river channel from entering the conventional fishway 4 during the maintenance period. The form of the partition 43 can be selected according to the characteristics of the project. The height of the sand retaining plate 44 should not be greater than 50 cm, which is used to further prevent the sediment that has been deposited from entering the conventional fishway 4 with the water flow.

[0055] The following is an application example of the present invention:

[0056] like Figure 1As shown, when the water level upstream of the dam 6 is higher than the lowest operating water level of the conventional fishway 4, the conventional fishway 4 operates normally, all gates in the fishway project are in a normal open state, the guide plate 121 of the water flow guide device 12 is arranged along the water flow direction, a sand retaining plate is arranged at the connection between the conventional fishway 4 and the sedimentation tank section 2, and a fish guide fence 51 is arranged obliquely at the downstream end of the simulated natural fishway 3. The water flows into the fishway project through the upstream water inlet section 1, most of the water in the sedimentation tank section 2 enters the simulated natural fishway 3, and a small amount of water after sedimentation enters the conventional fishway 4. The water in the simulated natural fishway 3 passes through the terminal fish guide fence 51 and merges with the water in the conventional fishway 4 in the downstream water outlet section 5 and flows out of the fishway project. In this process, the function of the sedimentation tank section 2 is to pass water and sediment, and the simulated natural fishway 3 is also an ecological flow discharge channel and an inlet water replenishment channel for the conventional fishway 4, which helps to increase the inlet flow rate of the fishway project and enhance the fish attracting effect. The downstream ecological flow can be controlled by adjusting the opening of the first upstream gate 31, and the remaining gates are kept at the maximum opening. Under the guidance of the fish guide fence 51, the migratory fish enter the conventional fishway 4 through the downstream outlet section 5, enter the sedimentation tank section 2 after passing through the conventional fishway 4, and finally enter the river through the upstream inlet section 1 to continue migrating.

[0057] When the water level upstream of the dam 6 is lower than the lowest operating water level of the conventional fishway 4, the conventional fishway 4 stops operating, the second upstream gate 41 and the second downstream gate 42 are in a closed state, the remaining gates in the fishway project are at their maximum opening, the guide plate 121 of the water flow guide device 12 is arranged along the water flow direction, and the fish guide fence 51 is removed at the downstream end of the simulated natural fishway 3. The water flows into the fishway project through the upstream water inlet section 1, all the water in the sedimentation tank section 2 enters the simulated natural fishway 3, and the water in the simulated natural fishway 3 directly flows into the downstream water outlet section 5, and then flows out of the fishway project. In this process, the function of the sedimentation tank section 2 is to pass water, and the simulated natural fishway 3 serves as an ecological flow discharge channel and a fish passing channel. Migratory fish enter the simulated natural fishway 3 through the downstream water outlet section 5, enter the sedimentation tank section 2 through the simulated natural fishway 3, and finally enter the river through the upstream water inlet section 1 to continue migrating.

[0058] When the sedimentation tank section 2 needs to be discharged, the angle of the guide plate 121 of the water flow guide device 12 is adjusted to change the direction of the water flow entering the sedimentation tank section 2, thereby achieving sediment discharge. When the sedimentation tank section 2 is discharged, the conventional fishway 4 stops running, and the second upstream gate 41 and the second downstream gate 42 are in a closed state. The sediment discharge operation is preferably carried out when the water level upstream of the dam 6 is high and during the non-main fish passage period. After the sediment discharge operation is completed, the second upstream gate 41 and the second downstream gate 42 should be opened to restore the normal operation of the conventional fishway 4.

[0059] When the conventional fishway 4 needs to be overhauled, the second upstream gate 41 and the second downstream gate 42 are closed, and the overhaul should be arranged during the period when the conventional fishway 4 is stopped. When the fishway project is overhauled as a whole, the water inlet gate 11, the first downstream gate 32 and the second downstream gate 42 are closed, and the overall overhaul should be arranged during the period when the water level upstream of the barrage 6 is low and the fish are not passing through.

[0060] In summary, the present invention is beneficial in that:

[0061] (1) It has multiple fishway operation modes, high adaptability to water level changes, and effectively improves reliability. When the conventional fishway operates normally, the simulated natural fishway operates as a channel for the ecological flow of the river and a water replenishment channel for the fishway project; when the conventional fishway stops operating, the simulated natural fishway serves as a channel for the ecological flow of the river and a channel for fish upstream migration. Due to the small difference in water level between upstream and downstream, the simulated natural fishway with multiple semi-cylindrical bluff bodies at the bottom is relatively short in length, and the flow state is relatively stable, which can provide a migratory channel for fish and improve the reliability of the project.

[0062] (2) The fishway has multiple functions, taking into account both ecological flow discharge and inlet water replenishment. When the upstream water level is higher than the lowest operating water level of the conventional fishway, the conventional fishway operates normally. Due to the increased water depth in the simulated natural fishway, the flow rate will increase significantly, and it is no longer suitable as a fish upstream channel. Its function is transformed into an ecological flow discharge channel, and the discharge flow is controlled by the gate to complete the ecological flow discharge. At the same time, since the conventional fishway and the simulated natural fishway share an outlet, when the conventional fishway operates normally, the function of the simulated natural fishway is transformed into a water replenishment channel, which can replenish water inside the fishway inlet, directly improving the attractiveness of the fishway inlet.

[0063] (3) Special sedimentation treatment to reduce the amount of sediment entering the fishway and reduce siltation in the fishway. The water entering from the common water inlet of the conventional fishway and the simulated natural fishway has a higher flow velocity along the simulated natural fishway side and a stronger sand-carrying capacity, while the water flow along the conventional fishway side has a significantly lower flow velocity due to the increase in the water-passing cross-section, and a weaker sand-carrying capacity. Therefore, the sedimentation effect will cause most of the sediment to concentrate at the bottom of the water layer. The sand retaining plate installed at the water inlet of the conventional fishway can further prevent the sediment that has already settled to the bottom from entering the conventional fishway, thereby greatly reducing the amount of sediment entering the conventional fishway and alleviating the siltation in the fishway.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A low-head dam fishway for high sediment content and large head fluctuation, arranged on the side away from the water diversion gate (7), characterized in that: It includes an upstream water inlet section (1), a sedimentation tank section (2), a simulated natural fishway (3), a conventional fishway (4) and a downstream water outlet section (5). The upstream water inlet section (1) is provided with a water inlet gate (11) and a water flow guide device (12) for changing the direction of water flow in sequence from the outside to the inside; The desilting tank section (2) is located between the upstream water inlet section (1) and the simulated natural fishway (3), and is in a trapezoidal shape, with its long sides respectively connected to the upstream water inlet section (1) and the simulated natural fishway (3), and its short sides connected to the conventional fishway (4); The simulated natural fishway (3) is a slope section, wherein a first upstream gate (31), a plurality of bluff bodies (33) and a first downstream gate (32) are sequentially arranged, and the plurality of bluff bodies (33) are arranged in a staggered manner; The downstream outlet section (5) is connected to the simulated natural fishway (3) and the conventional fishway (4) respectively, and a fish guide fence (51) is provided at the junction; the angle between the downstream outlet section (5) and the main stream of the river is less than 45°; The conventional fishway (4) is a slope section, and a second upstream gate (41) and a sand retaining plate (44) are provided at the connection with the sedimentation tank section (2), and a second downstream gate (42) is provided at the connection with the downstream outlet section (5), and a plurality of partitions (43) are provided inside; The upstream water inlet section (1), the sedimentation tank section (2) and the downstream water outlet section (5) are all flat slope sections.

2. The low head dam fishway according to claim 1, characterized in that: The water flow guiding device (12) comprises a plurality of guide plates (121) arranged at intervals, and the center distance between two adjacent guide plates (121) is not less than 30 cm.

3. The low head dam fishway according to claim 1, characterized in that: The slope of the simulated natural fishway (3) is no more than 10%.

4. The low head dam fishway according to claim 1, characterized in that: The height of the bluff body (33) is 50 cm, and the distance between two adjacent bluff bodies is 30-50 cm.

5. The low head dam fishway according to claim 1, characterized in that: The height of the sand retaining plate (44) is no more than 50 cm.

6. The low head dam fishway according to claim 1, characterized in that: The fish guide fence (51) is a grid structure, and the maximum width of the grid is no more than 30 mm.

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