An ecological fish guiding and returning facility suitable for overflow weir and adaptable to water level fluctuation

Abstract

The present application relates to the field of water conservancy project regulation and storage lake construction, and particularly relates to an ecological fish guiding and returning facility suitable for overflow weir and adaptable to water level fluctuation. A fish passing channel is arranged on one side of the overflow weir, and connects the present river channel and the regulation and storage lake. The fish passing channel adopts an integrated structure of a pool type fishway and a slope type fishway. A concrete cushion layer is arranged below the mortar jointed river stone foundation, the mortar jointed river stone is arranged above the concrete cushion layer, natural pebbles are arranged on the surface of the mortar jointed river stone and are subjected to bionic rough processing, and a mortar smoothing layer is arranged on the surface of the reserved partition plate of the mortar jointed river stone. Through the combination of the pool type fishway and the slope type fishway, the step design of the overflow weir and the slope optimization, the self-adaptation to the water level fluctuation of the regulation and storage lake and the overflow weir is realized. No matter whether the water level rises or falls, the water flow of the fish passing channel can be kept smooth and the connectivity is good.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering reservoir construction, specifically to an ecological fish diversion and return fish passage facility suitable for overflow weirs and adaptable to water level fluctuations. Background Technology

[0002] Fish return passage systems are designed by creating a series of gently flowing steps or chambers that allow fish to gradually "jump" over dams and eventually return smoothly to their upstream breeding grounds. The core idea is to reduce water flow speed, provide resting space, and guide fish to move upstream. Common types include stepped, ramp, and fish elevator systems.

[0003] Currently, common fish diversion and return facilities are generally constructed with reinforced concrete, much like "highways" built specifically for fish, allowing them to safely pass through man-made obstacles such as dams and sluices and smoothly return upstream. However, in urban water storage lake construction scenarios, due to the large fluctuations in the overflow weir and water level of the water storage lake, these facilities cannot completely replace the connectivity of natural rivers, and subsequent maintenance (such as silt removal and structural repair) requires continuous investment, increasing the operating costs of water conservancy projects. Summary of the Invention

[0004] To address the problems of existing technologies, this invention provides an ecological fish diversion and return system suitable for overflow weirs and adaptable to water level fluctuations.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An ecological fish diversion and return fish passage facility suitable for overflow weirs and adaptable to water level fluctuations is provided. The fish passage is set on one side of the overflow weir, connecting the existing river channel and the regulating lake. The fish passage adopts an integrated structure combining a pool-type fish passage and a sloping fish passage. The concrete cushion layer is laid under the masonry river stone foundation, the masonry river stone is built on top of the concrete cushion layer, the natural pebble lining is laid on the surface of the masonry river stone and given a biomimetic rough treatment, and the mortar smoothing layer is set on the surface of the reserved partition of the masonry river stone.

[0007] A step is reserved every 20cm on the overflow weir. The overall slope of the masonry river stone is 1:20, and the masonry height reaches near the normal water level. A 0.5m high partition is reserved on the masonry river stone. The partition is plastered with 1:2.5 cement mortar to form a mortar smoothing layer.

[0008] The pond-type fishway consists of multiple interconnected pond chambers, each measuring 2m × 2m. The partitions are 1.5m long, with a 0.5m gap between adjacent partitions reserved as a passage for migrating fish.

[0009] The concrete cushion layer is 10cm thick, and a compacted soil layer is laid underneath it. The compaction degree of the compacted soil layer is ≥95%. The size of the natural pebble facing is 20mm-50mm.

[0010] The masonry river stones are constructed using M10 cement mortar, ensuring tight connections between the stones without any loosening.

[0011] The overflow weir has a reserved step width of 30cm, the step surface is flat, and it is firmly connected to the overall structure of the overflow weir.

[0012] The natural pebble veneer is fixed with cement mortar, and the pebble surface is slightly polished, with a friction coefficient ≥0.35.

[0013] The water flow velocity in the fish passage is controlled at 0.3-0.5 m / s to meet the needs of fish migration.

[0014] The concrete cushion layer has a strength ≥ C15, and the surface flatness is controlled during the pouring process.

[0015] The fish passageway needs to be cleaned of silt regularly, every 3 months. If the pebble lining becomes loose, it should be repaired with cement mortar.

[0016] Compared with existing technologies, the beneficial effects of this invention are as follows: By combining pool-type and sloping-type fish passages, and designing overflow weir steps and optimizing the slope, it achieves self-adaptation to fluctuations in the water level of the regulating lake and overflow weir. Regardless of whether the water level rises or falls, the water flow in the fish passage remains gentle and the connectivity is good, increasing the fish passage efficiency by more than 60%, which is significantly better than existing reinforced concrete fish passage facilities. According to relevant data, most existing fish passage facilities have a fish passage rate of only about 10-15%, while based on experimental data and the design principle of the stepped weir spacing, the fish passage rate of this invention reaches 92% when the step spacing is 20cm, which is 62 percentage points higher than the 30% of existing fish passages, demonstrating a significant advantage in fish passage performance. By using natural pebble lining to create a biomimetic rough surface, a natural riverbed environment is simulated. This not only facilitates fish climbing but also provides them with habitat and foraging space, reducing the interference of artificial facilities on the aquatic ecosystem. This effectively ensures the safety of fish migration, maintains fish populations, preserves ecological balance, and protects aquatic biodiversity. Experimental data shows that with a 20-50mm natural pebble lining, the fish climbing pass rate reaches 93%, an increase of 68 percentage points compared to ordinary reinforced concrete surfaces (pass rate 25%), demonstrating significant ecological benefits. Construction and maintenance costs are significantly reduced: Using natural materials such as masonry river stones and natural pebbles to replace existing all-reinforced concrete structures reduces construction costs by more than 30% (down to 196 yuan / ㎡, a significant reduction compared to the existing reinforced concrete fishway at 280 yuan / ㎡). Simultaneously, natural materials have strong wear resistance and impact resistance, and the silt is easy to clean and the structure is easy to repair, reducing subsequent maintenance costs by more than 40% (accounting for only 4.8% of the annual construction cost, a significant reduction compared to the 8% of existing technologies). Attached Figure Description

[0017] Figure 1 This invention relates to a plan view of an overflow weir and an ecological fish diversion and return fish passage facility that can adapt to water level fluctuations;

[0018] Figure 2 This invention is applicable to overflow weirs and is a cross-sectional view of an ecological fish diversion and return fish passage facility that can adapt to water level fluctuations.

[0019] Explanation of the attached diagram labels: 1. Existing river channel; 2. Overflow weir; 3. Masonry river stone; 4. Regulating lake water level; 5. River channel water level; 6. Regulating lake; 7. Fish passage; 8. Natural pebble veneer; 9. Mortar leveling layer; 10. Masonry river stone foundation; 11. Concrete subbase. Detailed Implementation

[0020] The present invention will be further described in detail below through embodiments; the embodiments are only used to illustrate the present invention and do not limit the scope of the present invention.

[0021] An ecological fish diversion and return passage facility suitable for overflow weirs and adaptable to water level fluctuations is proposed. The fish passage 7 is set on one side of the overflow weir 2, connecting the existing river channel 1 and the regulating lake 6. It adopts an integrated structure combining a pool-type fishway and a sloping fishway. It is different from the limitations of using the two types of fishways separately in the existing technology. It takes advantage of the sloping fishway's small footprint and adaptability to the slope of the overflow weir 2, and also takes advantage of the pool-type fishway's gentle water flow and the provision of resting space, to achieve the synergistic effect of "sloping guidance and pool rest", which is suitable for the use scenario of water level fluctuations in the overflow weir 2. A step is reserved every 20cm in the concrete overflow weir 2, with a step width of 30cm. This ensures that the step is firmly connected to the overall structure of the overflow weir 2, while also ensuring that the surface of the step is flat and suitable for the subsequent connection of the fish passage 7. The spacing of the steps has been optimized through repeated tests. This not only ensures the structural integrity of the overflow weir 2, but also adapts to the water flow adjustment when the water level fluctuates, so that the water flow speed is stabilized at 0.3-0.5m / s (the suitable speed for fish migration), solving the problem of excessively rapid water flow or interruption of flow when the water level fluctuates in the existing facilities. A 10cm thick concrete cushion layer is laid beneath the masonry river stone foundation 3, with a concrete strength ≥C15. Surface flatness is controlled during pouring. A compacted subsoil layer is laid beneath the concrete cushion layer, with a compaction degree ≥95%. This design ensures the overall load-bearing capacity of the facility while avoiding the rigidity defects of a fully reinforced concrete structure. Simultaneously, the compacted subsoil layer acts as a buffer, reducing the impact of water level fluctuations on the facility foundation and extending its service life. Existing technologies often employ thick reinforced concrete cushion layers. This invention, by optimizing the cushion layer thickness and material combination, reduces construction costs while ensuring strength and facilitating later maintenance. River stones were laid on a concrete foundation using M10 cement mortar to ensure tight connections between stones without loosening. The overall slope of the masonry was designed to be 1:20, a slope that has been tested and verified to both accommodate the installation angle of the overflow weir 2 and ensure a gentle water flow. The masonry of river stones 3 was laid to a height near the normal water level, with a 0.5m high partition reserved. The partition was finished with 1:2.5 cement mortar to form a smooth mortar layer 9. The partition design further diverts and buffers the water flow, preventing the water from concentrating and becoming too fast. Key innovation The key feature is that 20mm-50mm natural pebbles are used as a facing on the surface of the masonry river stone 3, and a biomimetic roughening treatment is applied (the surface of the pebbles is slightly polished) to simulate the surface morphology and friction coefficient of a natural riverbed (friction coefficient ≥0.35). This solves the problem that the surface of existing reinforced concrete facilities is smooth and fish have difficulty climbing. This biomimetic design is not a simple material replacement, but a creative optimization that combines the climbing habits of fish. It can significantly improve the success rate of fish migration, and the use of natural materials can reduce the cost of later repairs.The pond-type fishway consists of multiple interconnected pond chambers, each optimized to 2m×2m in size, with a partition length of 1.5m and a 0.5m gap between adjacent partitions for migratory fish passage. The pond chamber dimensions are specifically designed to ensure that fish have ample resting space while avoiding excessive space occupation and poor water flow caused by overly large chambers. The 0.5m passage width is suitable for the body size of most migratory fish, solving the defects of existing pond-type fishways that are unreasonable in size and obstruct fish passage. This size design is the optimal solution determined through multiple sets of experiments based on the spatial constraints of the overflow weir 2 of the urban regulating lake 6 and the migratory habits of fish.

[0022] To verify the rationality of the key design parameters of this invention, multiple sets of comparative experiments were conducted. The experimental results are as follows, fully demonstrating the superiority of the technical solution of this invention:

[0023] 1. Comparison Experiment of Step Spacing: The experimental conditions were that the overflow weir water level fluctuated within the range of 0.5-1.5m, and 50 common local migratory fish (crucian carp and common carp) were selected. The effects of different step spacing on water flow velocity and fish passage rate are shown in the table below:

[0024] Step spacing (cm) Water flow velocity (m / s) when water level fluctuates by 0.5m Water flow velocity (m / s) when water level fluctuates by 1.5m Fish pass rate (%) Structural stability (1-10 points) 10 0.25 0.40 78 6 (Easily falls off) 20 (This invention) 0.32 0.48 92 9 (Stable) 30 0.45 0.65 65 8 (Relatively stable) 40 0.58 0.82 42 9 (Stable)

[0025] Experimental results show that the water flow velocity increases linearly with the increase of the step spacing, and its variation law can be quantitatively verified by fluid dynamics formulas. The formula for calculating the water flow velocity suitable for the overflow weir fish passage scenario is as follows: ,in The velocity of the water flow in the fish passage is (m / s). The step throttling coefficient (the present invention has been experimentally calibrated to be 0.62, which differs from the conventional design of 0.8-1.0). The acceleration due to gravity is 9.8 m / s². The step height is 0.2m, or 20cm. The slope angle of the fish passage (corresponding to a 1:20 slope). Substituting the step spacing parameters of this invention into the formula, we can calculate... The data perfectly matched the experimental data, proving the scientific validity of the step spacing design, rather than random selection. Furthermore, the relationship between fish passage rate and water flow velocity can be demonstrated by the formula... Quantification, among which The fish passage rate (%). This represents the maximum throughput at the optimal flow rate (92% in this invention). The fitting factor (test calibration is 8.5) is used. The optimal migration velocity for fish is 0.4 m / s. This represents the actual water flow velocity. Substitute the values ​​corresponding to different step spacings... The change in throughput can be quantified, confirming that the throughput is highest at a spacing of 20cm. In summary, when the step spacing is ≤20cm, the water flow velocity remains within the suitable range of 0.3-0.5m / s for fish. The fish throughput first increases and then decreases with increasing step spacing, reaching a peak of 92% at 20cm. When the spacing is too large (≥30cm), the water flow velocity exceeds the fish's adaptive range, and the throughput decreases significantly. The structural stability slightly improves with increasing step spacing, but the structure is prone to detachment at a spacing of 10cm. The optimal step spacing for overall performance is 20cm, which is consistent with the design of this invention.

[0026] 2. Pebble Size Comparison Experiment: The experimental conditions were a water flow velocity of 0.4 m / s (suitable flow velocity), and 50 common local migratory fish (crucian carp and common carp) were selected. The coefficient of friction between the pebble surfaces was measured using a standard friction meter. The effects of different pebble sizes on the coefficient of friction and the fish climbing success rate are shown in the table below:

[0027] Pebble size (mm) coefficient of friction Fish climbing success rate (%) Surface flatness (1-10 points) 10-20 0.22 75 9 (flat) 20-50 (This invention) 0.35 93 8 (relatively flat) 50-80 0.41 88 6 (Uneven) 80-100 0.45 72 4 (Easily loosened)

[0028] Experimental results show that the coefficient of friction increases with increasing pebble size, while the fish climbing success rate first increases and then decreases with increasing pebble size. When the pebble size is 20-50mm, the coefficient of friction reaches 0.35, which satisfies the friction force required for fish climbing (≥0.30) and ensures the flatness of the surface, resulting in a fish climbing success rate of 93%. When the pebble size is >50mm, although the coefficient of friction further increases, the surface becomes uneven and easily loosened, causing fish to be easily obstructed during climbing, and the success rate decreases. Therefore, 20-50mm is the optimal pebble size, which is consistent with the design of this invention.

[0029] The specific implementation steps are as follows:

[0030] 1. Foundation construction: First, clean up the construction area around the overflow weir 2. After excavating to the design depth, compact the underlying soil in layers. After compaction, conduct a compaction test to ensure that the compaction degree is ≥95%. Pour a 10cm thick concrete cushion layer on the compacted soil. The concrete strength is ≥C15. Control the surface flatness during the pouring process. After the concrete has cured to the design strength, proceed to the next process.

[0031] 2. Pre-reserved steps for overflow weir 2: During the construction of concrete overflow weir 2, a step is reserved every 20cm, with a step width of 30cm, to ensure that the step is firmly connected to the overall structure of overflow weir 2, and at the same time ensure that the surface of the step is flat and suitable for the subsequent connection of fish passage 7.

[0032] 3. Construction of mortar-grouted river stones 3: On the concrete foundation, river stones are laid using M10 cement mortar. The overall slope of the masonry is controlled at 1:20. During the masonry process, it is ensured that the river stones are tightly connected and there is no loosening. The height of the mortar-grouted river stones 3 is built up to near the normal water level line, and a 0.5m high partition is reserved. The partition is plastered with 1:2.5 cement mortar to form a mortar smoothing layer 9, ensuring that the surface of the partition is smooth and firm, and playing a role in diverting and buffering water flow.

[0033] 4. Biomimetic treatment: On the surface of the masonry river stone 3, natural pebbles of 20mm-50mm are used for surface treatment. The surface is bonded with cement mortar to ensure that the pebbles are firmly fixed. At the same time, the surface of the pebbles is slightly polished to create a biomimetic roughness, simulating the friction coefficient of a natural riverbed, which makes it easier for fish to climb.

[0034] 5. Pool and passageway construction: Divide the pools into 2m×2m sections, with partition length controlled at 1.5m. Reserve a 0.5m passageway for migrating fish between the partitions. Connect multiple pools in series to form a continuous fish passageway 7, ensuring that the water flow in the passage is gentle and the flow velocity is controlled at 0.3-0.5m / s to meet the needs of fish migration.

[0035] 6. Post-construction maintenance: After construction is completed, the silt in the fish passage 7 should be cleaned regularly (once every 3 months). The cleaning process is simple and does not require the demolition of the structure. If the pebble lining becomes loose, it should be repaired with cement mortar in time. The maintenance cost is low and the operation is simple.

Claims

1. An ecological fish diversion and return system suitable for overflow weirs and adaptable to water level fluctuations, characterized in that, The fish passage is located on one side of the overflow weir, connecting the existing river channel and the regulating lake. The fish passage adopts an integrated structure combining a pool-type fish passage and a sloping fish passage. The concrete cushion layer is laid under the masonry river stone foundation, the masonry river stone is built on top of the concrete cushion layer, the natural pebble lining is laid on the surface of the masonry river stone and given a biomimetic rough treatment, and the mortar smoothing layer is set on the surface of the reserved partition of the masonry river stone. A step is reserved every 20cm on the overflow weir. The overall slope of the masonry river stone is 1:20, and the masonry height reaches near the normal water level. A 0.5m high partition is reserved on the masonry river stone. The partition is plastered with 1:2.5 cement mortar to form a mortar smoothing layer. The pond-type fishway consists of multiple interconnected pond chambers, each measuring 2m × 2m. The partitions are 1.5m long, with a 0.5m gap between adjacent partitions reserved as a passage for migrating fish. The concrete foundation layer is 10cm thick, and a compacted soil layer is laid underneath it. The compaction degree of the compacted soil layer is ≥95%. The size of the natural pebble facing is 20mm-50mm.

2. The ecological fish diversion and return system for fish passage, suitable for overflow weirs and adaptable to water level fluctuations, as described in claim 1, is characterized in that... The masonry river stones are constructed using M10 cement mortar, ensuring tight connections between the stones without any loosening.

3. The ecological fish diversion and return system for fish passage, suitable for overflow weirs and adaptable to water level fluctuations, as described in claim 2, is characterized in that... The overflow weir has a reserved step width of 30cm, the step surface is flat, and it is firmly connected to the overall structure of the overflow weir.

4. The ecological fish diversion and return fish passage facility suitable for overflow weirs and adaptable to water level fluctuations as described in claim 3, characterized in that, The natural pebble veneer is fixed with cement mortar, and the pebble surface is slightly polished, with a friction coefficient ≥0.

35.

5. The ecological fish diversion and return fish passage facility suitable for overflow weirs and adaptable to water level fluctuations as described in claim 4, characterized in that, The water flow velocity in the fish passage is controlled at 0.3-0.5 m / s to meet the needs of fish migration.

6. The ecological fish diversion and return fish passage facility suitable for overflow weirs and adaptable to water level fluctuations, as described in any one of claims 1-5, is characterized in that... The concrete cushion layer has a strength ≥ C15, and the surface flatness is controlled during the pouring process.

7. The ecological fish diversion and return fish passage facility suitable for overflow weirs and adaptable to water level fluctuations as described in claim 6, characterized in that, The fish passageway is regularly cleaned of silt every 3 months, and the pebble lining is repaired with cement mortar when it becomes loose.

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