A biological connectivity channel and its design method

Abstract

This invention relates to a bio-connectivity channel and its design method, belonging to the field of tidal flat remediation engineering technology. Addressing the problems of poor permeability of silt-promoting dikes, insufficient water continuity between reservoirs, and inadequate biological flow in existing tidal flat remediation projects, this invention proposes a bio-connectivity channel composed of a prefabricated, cavity-type component with no elevation difference and an artificial reef system. The prefabricated component forms a bidirectional, full-tidal passageway by incorporating longitudinal / transverse baffles, resting pools, and bottom slab openings. The supporting design method includes steps such as data collection and determination of typical tidal levels, numerical simulation of the flow field, optimization of prefabricated component dimensions (based on suitable flow velocities for fish), structural stability verification, and artificial reef system installation. This channel can effectively improve hydraulic communication and biological flow between reservoirs, reduce the obstructive impact of engineering on aquatic organisms, and create habitats for benthic organisms.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy engineering technology, and relates to tidal flat remediation engineering, and particularly to a biological connectivity channel and its design method applicable to coastal tidal flat remediation engineering. Background Technology

[0002] Coastal tidal flat management projects are an important means of protecting and utilizing coastal wetlands. The core engineering measure typically involves constructing a three-sided closed silt-promoting dike, allowing water exchange only through the near-shore tidal inlet. However, traditional silt-promoting dikes often employ sloping or vertical structures with poor permeability. For example, while the permeable revetment structure disclosed in Chinese patent CN104912037A improves permeability to some extent, it does not specifically address the need for biological circulation. According to the "Design Standard for Tidal Flat Management and Seawall Engineering" (DG / TJ...),... (08-2111-2024) The crest elevation of the silt-promoting dam is generally not lower than the average high tide level, resulting in significant limitations on water exchange between reservoirs: First, the water passage time is short. According to statistics, the water passage time in the Yangtze River Estuary during the tidal cycle above the average high tide level accounts for only 30%, with only brief water passage at high tide and complete blockage at low tide. Second, the water passage surface is narrow, relying solely on a single tidal inlet, resulting in high flow velocity at the tidal inlet, which is usually greater than 1.0 m / s (far exceeding the limit flow velocity of 0.2-0.7 m / s for most migratory fish). Third, the bidirectional flow is poor, and traditional structures cannot achieve bidirectional hydraulic exchange throughout the tidal cycle, disrupting the continuity of water between reservoirs.

[0003] Existing engineering measures for biological connectivity are mainly focused on the field of river ecological restoration, such as stepped fish passages (a control method for stepped fish passage facilities suitable for high dams and steep slopes disclosed in Chinese patent CN101638889B) and tidal estuary fish passages (Chinese patent CN115419028 B). However, these fish passage facilities and methods are suitable for environments with one-way water level difference and are difficult to adapt to tidal flat environments with large tidal ranges, frequent rises and falls in water level, and bidirectional water level exchange needs.

[0004] In existing tidal flat management projects, the poor permeability of the dikes leads to poor hydraulic communication and biological circulation between reservoir areas, disrupting the continuity and bidirectional exchange of water between reservoirs. This has a significant impact on the biological circulation of aquatic organisms, especially fish. Furthermore, the design methods in the field of tidal flat management projects usually rely on empirical formulas, and the design results often deviate significantly from the actual situation. With the increasing demand for biological connectivity in coastal wetlands, there is an urgent need to develop a new type of biological connectivity channel and design method that can not only meet the siltation promotion function of tidal flats, but also achieve bidirectional water flow throughout the entire tidal cycle, precisely regulate the flow velocity to a suitable range for fish, and create habitats for benthic organisms. Summary of the Invention

[0005] To address the aforementioned technical problems, the first objective of this invention is to provide a design method for biological communication channels, which involves using numerical simulation software to simulate the flow field, accurately design the structure of prefabricated components, and optimize their dimensions. The second objective of this invention is to provide a biological communication channel.

[0006] To achieve the aforementioned primary objective, this invention provides a design method for a biological connectivity channel. Based on the design conditions, water depth, and biological characteristics of the tidal flat reclamation area, the method employs numerical simulation software to simulate the flow field and precisely design and optimize the structure and dimensions of prefabricated components. A bidirectional Z-shaped channel is designed within the asymmetrically perforated, hollow prefabricated component. Longitudinal and transverse baffles divide the channel into multiple levels of slow-flowing pools. The asymmetric openings connect the two sides of the reclamation area within the Z-shaped channel, forming a biological connectivity channel between the tidal flat reclamation area and the reclamation area. A riprap bed is installed at the bottom of the biological connectivity channel to form a prefabricated component hybrid dike. Artificial reefs are set along the hybrid dike to guide aquatic organisms to discover the asymmetric openings of the Z-shaped channel. This method not only satisfies the tidal flat siltation function in coastal tidal flat reclamation projects but also enables bidirectional water flow throughout the entire tidal cycle, precisely controlling the flow velocity to a suitable range for fish and creating habitats for benthic organisms. The bidirectional water flow throughout the entire tidal cycle means that water can flow between the two sides of the siltation-promoting dike during both high and low tides in the project area.

[0007] Furthermore, it includes the following steps:

[0008] S1. Basic Data Collection and Parameter Determination: Collect hydrological, engineering geological and topographical, and aquatic biological species data of the project area; statistically analyze hourly tidal processes; determine typical tidal processes; and determine the design flow velocity range based on the induced flow velocity, preferred flow velocity, and limiting flow velocity of common fish species in the project area.

[0009] S2. Flow field simulation and location selection: Based on the plan layout of the tidal flat management reservoir area, the flow field in the reservoir area under typical tidal processes is calculated, the representative water level difference and corresponding flow velocity on both sides of the siltation-promoting dam are extracted, and the location of the biological connectivity channel is selected.

[0010] S3. Precast component structural design and dimensional optimization: Propose a cavity-type precast component structure with asymmetric openings. Combine the water level difference and flow velocity data from step S2 to calculate the flow velocity inside the cavity of the precast component and optimize the dimensions of the outer wall, partition, rest pool, and openings to ensure that the flow velocity inside the cavity is within the design flow velocity range.

[0011] S4. Structural stability verification: Verify the anti-slip, anti-tilting and foundation bearing capacity of the precast components. If they do not meet the requirements of the specifications, adjust the dimensions and repeat steps S3-S4.

[0012] S5. Artificial Reef System Setup: Artificial reef systems are set up on the outside of the openings in the prefabricated components to enhance the fish attraction effect at the inlet and outlet.

[0013] Furthermore, the method for determining the typical tidal process in step S1 is to use the Pearson Type III curve to determine the typical tidal process.

[0014] Furthermore, the method for calculating the flow field in the reservoir area under a typical tidal process in step S2 is to use Delft-3D or MIKE21 numerical simulation software.

[0015] Furthermore, in step S2, the location of the biological communication channel is selected in a section of the silt-promoting embankment where the flow velocity along the embankment is in the range of 0.5 to 1.0 m / s and the distance from the tidal inlet is not less than 1 km.

[0016] Furthermore, the calculation of the flow velocity inside the cavity of the precast component in step S3 is performed using CFD software.

[0017] Furthermore, the prefabricated components described in step S3 can be combined in multiple ways to extend the cavity length, in order to adapt to different water level differences and flow rate requirements.

[0018] Furthermore, in step S3, openings can be added to both sides of the prefabricated component, and the bottom plate can be roughened to reduce turbulence and flow velocity within the cavity.

[0019] To achieve the second objective mentioned above, the present invention provides a biological communication channel determined according to the design method of the biological communication channel, comprising a cavity-type prefabricated component with asymmetric openings and a reef system;

[0020] The prefabricated component is mainly composed of a lower rectangular block and an upper trapezoidal block. The rectangular block has a cavity in the middle and is connected to a perforated rectangular base plate. The elevation of the base plate meets the requirement that the water depth at the low tide level is not less than 1m. The trapezoidal block has a cavity in the middle and its top elevation is not lower than the average high tide level.

[0021] The asymmetric opening includes a first opening and a second opening, which are respectively opened on opposite sides of the longitudinal ends of the rectangular block, forming an asymmetric layout without height difference;

[0022] A longitudinal partition is provided inside the rectangular block cavity along the dam axis. The height of the longitudinal partition is the same as the height of the component. Its direction starts from the middle of the first opening, extends through the longitudinal center line, and ends at the middle of the second opening, dividing the cavity into a first channel and a second channel that are independent of each other and have a Z-shaped direction.

[0023] Transverse partitions are spaced apart in the first and second channels to form several interconnected multi-level buffer pools; the artificial reef group is located outside the first and second openings.

[0024] Furthermore, the transverse partitions in the first channel are arranged in descending order from the first opening to the second opening, and the transverse partitions in the second channel are arranged in ascending order from the first opening to the second opening.

[0025] Furthermore, the transverse partition includes a main transverse partition and a secondary transverse partition, which are arranged alternately.

[0026] The main transverse partition is perpendicular to the inner wall and bottom plate of the rectangular block, extends from the inner wall to near the longitudinal partition, and is 1.5 to 2.0 m apart from the longitudinal partition.

[0027] The secondary transverse partition is perpendicular to the longitudinal partition and the bottom plate, and extends from the longitudinal partition to the middle of the first and second channels, with a length of 1.5 to 2.0 m.

[0028] The main transverse partition and the secondary transverse partition are spaced 1.5 to 2.0m apart, and their height is 0.8 to 1.2m above the bottom plate;

[0029] The thickness of the longitudinal partition is 0.2 to 0.3 m.

[0030] Furthermore, the multi-stage buffer pool includes a regular pool chamber and a resting pool chamber. The bottom plate of the resting pool chamber is 0.3 to 0.5 m deeper than that of the regular pool chamber, and the length of the resting pool chamber is 1.5 times that of the regular pool chamber.

[0031] Furthermore, the Z-shaped channel is oriented as follows: the longitudinal partition is perpendicular to the bottom plate, starting from the middle position of the first opening, turning 90° to the longitudinal center line and then extending along the longitudinal center line towards the second opening, turning 90° again at the point where the midpoint of the bottom plate of the second opening is perpendicular to the longitudinal center line and extending to the middle position of the second opening.

[0032] Furthermore, the prefabricated component has toe-shaped structures on both sides of its base plate.

[0033] The main principles of this invention are as follows:

[0034] This invention achieves multi-objective synergy of "hydraulic connectivity, biological circulation, and ecological restoration" in the reservoir area for tidal flat management through asymmetric openings, bidirectional Z-shaped channels, alternating layout of main and auxiliary transverse diaphragms, and collaborative design of artificial reefs. Its main principles are explained below:

[0035] 1. Precise two-way water flow control

[0036] Based on the bidirectional tidal flow characteristics, the asymmetrical opening layout with no elevation difference and the bidirectional Z-shaped channel are adapted to the main directions of the rising and falling tides respectively, avoiding turbulence interference caused by the collision of water flows. Combined with the "alternating high and low levels" design of the main and auxiliary transverse baffles, the flow velocity in the cavity is precisely controlled to a suitable range for fish (0.2~0.7m / s) by using the stepped water level difference (Δh) and the power dissipation per unit water volume (E=ρgQΔh / V) mechanism, so as to achieve stable bidirectional water passage throughout the entire tidal cycle and solve the limitation of traditional dikes that only allow water to pass briefly at high tide.

[0037] 2. Guiding biological behavioral adaptation

[0038] Synergistic effects are achieved through flow field gradient directional guidance and micro-habitat nesting: Z-shaped independent channels divided by asymmetric openings and longitudinal baffles, combined with the "alternating high and low" design of main and secondary transverse baffles, form an "S"-shaped flow path and a pressure gradient generated by the height difference of the baffles. The fish's lateral line system is used to sense the direction of water flow, reducing the risk of fish getting lost during migration. The independent pool chambers (including resting pools with a depth of 0.3-0.5m) formed by alternating main and secondary baffles construct a "rapid flow-slow flow-vortex" composite flow field, which meets the flow velocity preferences of different fish (adults / juveniles) and the attachment needs of benthic organisms (shellfish, algae), thus realizing the integration of the functions of "migration channel" and "ecological habitat".

[0039] 3. Hydrodynamic-Structural-Ecological Coupling

[0040] The system adopts an alternating layout of "strong dissipation of main transverse baffles + fine adjustment of secondary transverse baffles". Through CFD simulation and anti-sliding and anti-tilting stability calculations, it balances the energy dissipation of water flow (E<200W / m³) and structural safety. The artificial reef group on the outside of the opening slows down the local flow velocity and enhances the fish attraction effect. Together with the slow flow environment inside the prefabricated components, it promotes sediment deposition and forms a benthic habitat. Ultimately, it achieves a win-win situation for both engineering and ecology, namely "siltation promotion function - biological connectivity - ecological restoration".

[0041] The beneficial effects achieved by this invention are as follows:

[0042] ① Improve biological flow between reservoirs: By forming a two-way full-tidal water passage through asymmetric open cavity prefabricated components, the problem of short water passage time and high flow velocity in traditional dikes is solved, providing a suitable migration environment for aquatic organisms such as fish and reducing the obstruction of the project on the natural activities of organisms;

[0043] ② Adaptable to various scenarios: Prefabricated components can be combined or the opening / partition size can be adjusted to adapt to different water level differences, flow velocities and engineering geological conditions, offering high flexibility;

[0044] ③ Enhance ecological benefits: The slow-flowing environment inside the cavity promotes sediment deposition, creating a habitat for benthic organisms; the artificial reefs set on the outside of the opening can slow down the local flow velocity, attract fish to gather, and improve the utilization rate of the biological channel;

[0045] ④ Structural safety and reliability: Through anti-sliding, anti-tilting and foundation bearing capacity calculations, the stability of precast components under wave and tide conditions is ensured, taking into account both ecological needs and engineering feasibility. Attached Figure Description

[0046] Figure 1 This is a top view schematic diagram of the layout of the tidal flat reservoir area in Embodiment 1 of the present invention.

[0047] Figure 2 For the present invention Figure 1 Schematic diagram of the AA section.

[0048] Figure 3 For the present invention Figure 2 Schematic diagram of the BB cross section.

[0049] Figure 4 For the present invention Figure 2 Schematic diagram of the CC section.

[0050] Figure 5a This is a typical cross-sectional velocity cloud diagram of the YZ plane in the axial direction of the CFD numerical model of the asymmetric open cavity type prefabricated component of Embodiment 1 of the present invention.

[0051] Figure 5b This is a typical cross-sectional velocity cloud diagram of the XY plane in the planar direction of the CFD numerical model of the asymmetric open cavity type prefabricated component of Embodiment 1 of the present invention.

[0052] Figure 6 This is a flowchart of a biological connectivity channel design method according to the present invention.

[0053] In the diagram, 1. Coastline; 2. Silt-promoting dike; 3. Tidal inlet; 4. Tidal flat reservoir area; 5. Biological communication channel; 6. Outer wall of prefabricated component; 7. Bottom slab; 8. Bottom slab opening; 9. Front and rear toes; 10. Asymmetrical opening; 10-1. First opening; 10-2. Second opening; 11. Transverse partition; 11-1. Main transverse partition; 11-2. Secondary transverse partition; 12. Longitudinal partition; 13. Resting pool; 14. Sealing plate; 15. Subgrade; 16. Artificial reef group; 17. Reservoir water level. Detailed Implementation

[0054] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0055] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0056] This invention provides a method for designing biological connectivity channels. First, data on tide levels, waves, engineering geology, and aquatic species in the tidal flat remediation project area are collected. Hourly tidal processes in the project area are statistically analyzed, and typical tidal processes are determined using Pearson Type III curves (referencing Appendix A of the "Design Code for Seawall Engineering" (GB / T51015-2014)). Then, numerical simulation software such as Delft-3D and MIKE21 are used to establish a numerical model of the project area. After model verification, the flow field within the reservoir area under typical tidal processes is calculated by inputting typical tidal boundaries, and representative water level differences and corresponding flow velocities on both sides of the silt-promoting dike are extracted. Common fish species in the project area are collected, and suitable flow velocity ranges (including induced velocity, preferred velocity, and limiting velocity) are determined as the design velocity range, referring to Appendix A of the "Design Guidelines for Fishways in Water Conservancy and Hydropower Projects" (SL 609-2013). Using representative water level differences and corresponding flow velocities as calculation conditions, the flow velocity within the cavity of the precast component is calculated using empirical formulas or CFD software. The empirical formulas or CFD calculations are performed by adjusting the dimensions of the precast component's outer wall, internal partitions, resting pool, and openings. The empirical formulas can be determined by referring to Appendices A and B of the "Sluice Gate Design Code" (SL265-2016). For CFD calculations, a model based on the precast component's dimensions must first be created. After generating a mesh, the design water level and flow velocity are input to calculate the flow field, velocity range, and size within the precast component's cavity, ensuring the flow velocity within the cavity is within the design velocity range. Then, wave elements and engineering geological conditions of the engineering area are used to verify the precast component's anti-sliding, anti-tilting, and foundation bearing capacity, ensuring the precast component's stress meets the code requirements. Finally, a certain number of artificial reefs are set up outside the openings of the precast component to increase the fish-attracting effect at the precast component's inlet and outlet, ultimately forming a biological connectivity channel connecting the tidal flat reservoir area and facilitating the flow of fish and other aquatic organisms, thus enhancing biological circulation between the tidal flat reservoir area and the reservoir area. The following steps are included:

[0057] Step S1: Collect hydrological, engineering geological, topographic, and aquatic biological species data for the project area; statistically analyze hourly tidal processes in the project sea area; and determine typical tidal processes using Pearson Type III curves. Based on aquatic biological species data and in conjunction with Appendix A of the "Design Guidelines for Fishway in Water Conservancy and Hydropower Projects" (SL 609-2013), determine the suitable current velocity range (including induced current velocity, preferred current velocity, and limiting current velocity) for common fish species in the project sea area as the design current velocity range.

[0058] Step S2: Based on the data from Step S1 and the layout plan of the tidal flat management reservoir area, a numerical model of the engineering area is established using numerical simulation software such as Delft-3D and MIKE21. After model verification, the flow field within the reservoir area under typical tidal conditions is calculated by inputting typical tidal boundary values, and representative water level differences and corresponding flow velocities on both sides of the silt-promoting dike are extracted. The applicable flow velocity range is considered, while minimizing the impact on the tidal flat management effect and flow field. Biological channels are arranged on dike sections with a flow velocity range of 0.5–1.0 m / s along the dike and a distance from the tidal inlet (not less than 1 km).

[0059] Step S3: A biological communication channel is proposed, consisting of an asymmetrically perforated cavity-type prefabricated component and a group of artificial reefs. The lower part of the prefabricated component is a rectangular block with a cavity in the middle. A longitudinal partition is set in the middle, and transverse partitions and resting pools are set at intervals along the longitudinal direction on both sides to form a two-way communication channel. It is connected to a perforated rectangular bottom plate. The elevation of the bottom plate should be able to meet the water level changes of the reservoir on both sides, ensuring that the water depth below the design low tide level is not less than 1m. Toe-shaped structures are set on both sides, with rectangular holes opened at asymmetrical positions on the outer walls of both sides of the block. A trapezoidal block is set on the upper part of the rectangular block. The trapezoidal block has a cavity in the middle, and the top elevation of the trapezoidal block is not lower than the average high tide level. A riprap foundation is set at the bottom of the prefabricated component to form a prefabricated component hybrid dike. This prefabricated component can realize two-way communication of water flow on both sides of the tidal flat reservoir.

[0060] Based on the data from step S2, the flow velocity within the cavity of the precast component is calculated using empirical formulas or CFD calculation software to determine the dimensions (length, width, height, and wall thickness) of the precast component's outer wall, internal partitions, resting pool, and openings, ensuring that the flow velocity within the cavity of the precast component is within the design velocity range. Simultaneously, structural design parameters such as the precast component's anti-slip, anti-tilting, and foundation bearing capacity are calculated.

[0061] Step S4: Determine whether the flow velocity inside the cavity of the precast component is within the design velocity range and whether the structural design parameters meet the specifications. If they do, the required precast component dimensions are obtained; if they do not, adjust the dimensions (length, width, height, and wall thickness) of the outer wall, internal partitions, and openings of the precast component, and repeat steps S3 to S5 until the design requirements are met.

[0062] Step S5: Set up a certain number of artificial reefs on the outside of the openings on both sides of the precast component to increase the fish attraction effect at the inlet and outlet of the precast component, making it easier for fish and other aquatic organisms to find the openings of the precast component, improving the utilization rate of the biological communication channel formed by the asymmetrically opened cavity type precast component, and achieving the goal of improving the biological circulation between the tidal flat and the reservoir.

[0063] In another embodiment, step S3 can extend the cavity length of the prefabricated component by combining multiple prefabricated components, so that the flow velocity inside the cavity of the prefabricated component meets the design flow velocity range under different representative water level differences and flowing velocities.

[0064] In another embodiment, step S3 may involve adding openings on both sides of the precast component and roughening the base plate to further reduce turbulence and flow velocity within the cavity of the precast component.

[0065] This embodiment also provides a biological communication channel designed according to the method, including an asymmetrically perforated cavity prefabricated component and a group of artificial reefs. The prefabricated component has rectangular asymmetrical openings at opposite positions on both sides of its outer wall. A longitudinal partition and two longitudinally spaced transverse partitions are set in the cavity to connect the water areas between the tidal flat and the reservoir, forming a bidirectional, full-tidal Z-shaped channel between the reservoir and the reservoir. The bidirectional, full-tidal passage means that water can pass through the biological channel during both high and low tides, flowing from the reservoir area with a high tide level to the reservoir area with a low tide level, improving the connectivity of aquatic organisms such as fish between the reservoir and reducing the obstruction impact of tidal flat management projects on aquatic organisms such as fish. The direction of the Z-shaped channel is as follows: the longitudinal partition is perpendicular to the bottom plate, starting from the middle position of the first opening, turning 90° to the longitudinal center line and extending along the longitudinal center line towards the second opening, turning 90° again at the point where the midpoint of the bottom plate of the second opening is perpendicular to the longitudinal center line and extending to the middle position of the second opening. The prefabricated component consists of a lower rectangular block and an upper trapezoidal block. The rectangular block has a cavity in the middle and is connected to a perforated rectangular base plate. The elevation of the base plate meets the requirement that the water depth at low tide is not less than 1m. The trapezoidal block has a cavity in the middle and its top elevation is not lower than the average high tide level. The asymmetrical opening includes a first opening and a second opening, which are respectively opened on opposite sides of the longitudinal ends of the rectangular block, forming an asymmetrical layout without elevation difference. A longitudinal partition is provided in the cavity of the rectangular block along the dam axis. The height of the longitudinal partition is the same as the height of the component. Its direction starts from the middle position of the first opening, extends through the longitudinal center line, and ends at the middle position of the second opening, dividing the cavity into a first channel and a second channel that are independent and have a Z-shaped direction. Transverse partitions are arranged at intervals in the first channel and the second channel to form several interconnected multi-level buffer pools. The artificial reef group is set outside the first opening and the second opening. The transverse partitions in the first channel are arranged in descending order from the first opening to the second opening, while the transverse partitions in the second channel are arranged in ascending order from the first opening to the second opening. Each transverse partition includes a main transverse partition and secondary transverse partitions, arranged alternately. The main transverse partition is perpendicular to the inner wall and bottom plate of the rectangular block, extending from the inner wall to near the longitudinal partition, with a distance of 1.5–2.0 m between it and the longitudinal partition. The secondary transverse partition is perpendicular to the longitudinal partition and bottom plate, extending from the longitudinal partition towards the middle of the first and second channels, with a length of 1.5–2.0 m. The main and secondary transverse partitions are spaced 1.5–2.0 m apart, with a height of 0.8–1.2 m above the bottom plate. The thickness of the longitudinal partition is 0.2–0.3 m. The multi-stage buffer pool includes a regular pool chamber and a resting pool chamber. The bottom plate of the resting pool chamber is 0.3–0.5 m deeper than that of the regular pool chamber, and its length is 1.5 times that of the regular pool chamber. The prefabricated component has toe-shaped structures on both sides of its base plate.

[0066] The prefabricated components of the biological communication channel of this invention are equipped with asymmetrical openings, longitudinal partitions, and a central partition, forming a two-way communication channel with a Z-shaped orientation within the reservoir area, providing a fishway-like function for fish migration within the reservoir area. A riprap bed is set at the bottom of the biological communication channel, forming a prefabricated component hybrid dike. A group of artificial reefs is set along the hybrid dike outside the rectangular asymmetrical openings, which can exert a fish-attracting effect, attracting fish into the biological communication channel. This provides a place for fish to rest and forage, guiding aquatic organisms to discover the asymmetrical openings of the Z-shaped channel. It not only meets the siltation-promoting function of coastal mudflat management projects, but also enables bidirectional water flow throughout the entire tidal cycle, precisely controlling the flow velocity to a suitable range for fish, and creating a habitat for benthic organisms.

[0067] After a period of operation, the slow-flowing environment within the prefabricated components of this bio-connecting channel will lead to sediment deposition, creating a favorable habitat for benthic organisms. The bio-connecting channel and its design method proposed in this invention can reduce the impact of tidal flat remediation projects on the habitats of aquatic organisms in the project area.

[0068] Example 1

[0069] Example 1 proposes a biological connectivity channel and design method for a tidal flat remediation reservoir area, such as... Figure 1 As shown, to address the problem of poor hydraulic and biological connectivity between the tidal flats and reservoir areas 4 caused by the silt-promoting dam 2, a biological connectivity channel for the tidal flat management reservoir area is designed. The design method for the biological connectivity channel is as follows:

[0070] Step S1: Taking the coastal mudflats of the Yangtze River estuary as an example, firstly, hydrological, engineering geological, topographic, and aquatic biological species data of the project area are collected. Hourly tidal levels in the project area are statistically analyzed, and typical tidal processes are determined using Pearson Type III curves. The determination of typical tidal processes is based on Appendix A of the "Design Code for Seawall Engineering" (GB / T51015-2014). Based on the data, the suitable current velocity range for common fish species in the project area is determined. This current velocity range includes induced current velocity, preferred current velocity, and limiting current velocity. The determination of suitable current velocity range for common fish species in the project area is based on Appendix A of the "Design Guidelines for Fishways in Water Conservancy and Hydropower Projects" (SL 609-2013). Taking the Yangtze River estuary anchovy as an example, the smallest sexually mature female anchovy is about 20cm in length, its preferred current velocity is 0.2–0.5 m / s, and its limiting current velocity is generally between 0.4 and 0.7 m / s.

[0071] Step S2: Based on the data from Step S1 and the layout plan of the tidal flat management reservoir area, Delft-3D is used to calculate the representative water level difference and corresponding flow velocity on both sides of the silt-promoting dike in the reservoir area under typical tidal processes. The dike locations with an average water level difference of no more than 0.5m and an average flow velocity of no more than the limit velocity of the anchovy (0.5m / s) are determined as the locations for setting up biological communication channels.

[0072] Step S3: Propose an asymmetric perforated cavity-type precast component. It includes an outer wall 6, the upper part of which is trapezoidal in shape, with a slope ratio of no more than 1:1 on both sides. The lower part consists of a base plate 7 and a base plate opening 8, with front and rear toes 9 on both sides. The outer wall 6 has a rectangular asymmetric opening 10 on each of the opposite sides at both longitudinal ends of the component. Each asymmetric opening 10 includes a first opening 10-1 and a second opening 10-2, located on opposite sides of the first and second longitudinal ends of the cavity-type precast component, forming an asymmetric layout with no height difference. The precast component contains longitudinal partitions 12 arranged along the longitudinal direction of the embankment. Transverse partitions 11 are arranged at intervals on both sides of the longitudinal partitions 12, with the transverse partitions 11 arranged in stages according to a certain height difference, forming a bidirectional full-tidal water passage between reservoir sections, which can serve as a biological passage for anchovies. Precast components are fitted with sealing plates 14 on both sides and a foundation bed 15 at the bottom;

[0073] Based on the data from step S2, CFD numerical simulation software is used to calculate the flow velocity within the cavity of the precast component. The steps for determining the design parameters are as follows.

[0074] 1. Create a CFD numerical model: Create a 3D model of the asymmetric open cavity precast component using software such as Revit and CAD, generate a .stl file, import it into Flow3D software to generate a computational mesh, set the computational boundary, the high water level side of the precast component is the average tide level of 2.0m and the traveling velocity is 0.5m / s, and the low water level side is 1.5m. The turbulence model adopts the RNG k-ε model.

[0075] 2. Model Calculation and Data Extraction: Run the computational model. After the calculation is completed, use CFD-POST post-processing software to extract and analyze the Flow3D calculation results, such as... Figure 5a , Figure 5b As shown, typical cross-sectional velocity cloud maps of the asymmetric open cavity type precast component in the YZ plane and XY plane directions are extracted, and the velocity data on the cross-section is read.

[0076] 3. Data Analysis and Evaluation: Based on the numerical simulation results, the inlet and outlet flow velocities and the flow velocity within the cavity are analyzed to determine whether they meet the preferred flow velocity range of the Yangtze River Estuary Coilia ectenes. If not, the asymmetric perforated cavity-type prefabricated components are adjusted, and the calculation and analysis are repeated until the design requirements are met. Calculations show that this embodiment has 31 chambers, spaced 10-20 times apart by partitions, with one resting chamber 2m long. The bottom of the resting chamber is 0.5m deeper than that of ordinary chambers, and the total length of the biological communication channel is 55m. This biological communication channel consists of 5 cavity-type prefabricated components, each 11m long.

[0077] Step S4: Calculate the structural design parameters of the precast components, such as anti-slip, anti-tilting, and foundation bearing capacity, and determine whether the flow velocity inside the biological communication channel cavity is within the suitable range for fish, and whether the structural design parameters meet the specifications. In this embodiment, all of these are met. If not, adjust the dimensions of the outer wall, internal partitions, openings, etc. of the precast components, and repeat steps S3 to S5 until the design requirements are met.

[0078] Step S5: Set up a group of 21 artificial reefs consisting of 3 rows and 7 columns outside the asymmetric opening 10 of the biological connection channel. The size of each reef is 1.5m×1.5m×1.5m. This will slow down the flow velocity in the local area at the inlet and outlet, increase the fish gathering effect at the inlet and outlet of the prefabricated components, and facilitate the gathering of aquatic organisms such as fish at the opening location, thereby achieving the goal of improving the biological circulation between the tidal flat and the reservoir.

[0079] The above solution is merely an illustration of a preferred embodiment, and is not limited thereto. Appropriate modifications can be made according to user needs when implementing this invention.

[0080] The foregoing descriptions and embodiments are provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be easily made to these contents, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, the present invention is not limited to the foregoing descriptions and embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from its scope should be within the protection scope of the present invention.

Claims

1. A method of designing a biological communication channel, characterized by, According to the design conditions, water depth and biological characteristics of the beach treatment reservoir area, the flow field is simulated by using numerical simulation software, and the structure and scale of the prefabricated component are precisely designed and optimized. A two-way Z-shaped channel is designed inside the non-asymmetrically opened cavity type prefabricated component without height difference, and the channel is divided into multiple slow-flow pools by designing longitudinal and transverse partitions. Combined with the "high-low step-by-step" design of the main and auxiliary transverse partitions, the stepwise water level difference and the unit water body power dissipation mechanism are utilized to form an "S"-shaped flow path and a pressure gradient generated by the height difference of the partitions. The two sides of the Z-shaped channel connected by the non-asymmetrically opened cavities form a biological connection channel between the reservoir areas of the beach treatment reservoir area. A riprap bed is arranged at the lower part of the biological connection channel to form a prefabricated component hybrid dike. Fish reefs are arranged along the hybrid dike to guide aquatic organisms to find the non-asymmetrically opened Z-shaped channel. The beach treatment dam can not only meet the beach treatment function in the coastal beach treatment project, but also realize two-way water passing in the whole tidal cycle, precisely control the flow rate to the suitable range of fish, and create habitats for benthic organisms. The two-way water passing in the whole tidal cycle means that the reservoir areas on both sides of the siltation promoting dam can pass water to each other during the flood and ebb tides in the engineering area.

2. The method of designing a biological communication pathway according to claim 1, wherein, The method comprises the following steps: S1. Collecting basic data and determining parameters: collecting hydrological, engineering geological and topographical data, and species data of aquatic organisms in the engineering area, counting the hourly tidal level process, and determining the typical tidal level process; determining the design flow rate range according to the sensitive flow rate, preferred flow rate and limit flow rate of common fish in the engineering sea area; S2. Flow field simulation and position selection: based on the planar layout scheme of the beach treatment reservoir area, the flow field in the reservoir area under the typical tidal level process is calculated, the representative water level difference and the corresponding flow rate on both sides of the siltation promoting dike are extracted, and the arrangement position of the biological connection channel is selected; S3. Structure design and scale optimization of prefabricated component: a non-asymmetrically opened cavity type prefabricated component structure is proposed, the flow rate in the cavity of the prefabricated component is calculated in combination with the water level difference and flow rate data of step S2, and the scales of the outer wall, partition, rest pool and opening are optimized so that the flow rate in the cavity is within the design flow rate range; S4. Structure stability checking: checking the sliding resistance, inclination resistance and foundation bearing capacity of the prefabricated component, and adjusting the scale and repeating steps S3-S4 if the requirements of the specification are not met; S5. Fish reef group setting: fish reefs are arranged outside the openings of the prefabricated component to enhance the fish gathering effect at the inlet and outlet.

3. The method of designing a bio-communication channel according to claim 2, wherein: The method for determining the typical tidal level process in step S1 is to determine the typical tidal level process by using a Pearson III type curve.

4. The method of designing a biological communication pathway according to claim 2, wherein: The method for calculating the flow field in the reservoir area under the typical tidal level process in step S2 is to use Delft-3D or MIKE21 numerical simulation software.

5. The method of designing a bio-communication channel according to claim 2, wherein: The position of the biological connection channel in step S2 is arranged at the dike section with a flow rate range of 0.5-1.0 m / s and a distance of not less than 1 km from the tidal inlet.

6. The method of designing a bio-communication channel according to claim 2, wherein: The calculation of the flow rate in the cavity of the prefabricated component in step S3 is to calculate the flow rate in the cavity of the prefabricated component by using CFD software.

7. The method of designing a bio-communication channel according to claim 2, wherein: The prefabricated component in step S3 can extend the cavity length by multiple combinations to adapt to different water level differences and flow rate requirements.

8. The method of designing a biological communication pathway according to claim 2, wherein: The two sides of the prefabricated component in step S3 can be additionally provided with openings, and the bottom plate can be roughened to reduce the turbulence and flow rate in the cavity.

9. A biological communication pathway as determined by the method of designing a biological communication pathway according to any one of claims 1 to 8, wherein, The method comprises a cavity type prefabricated component with non-asymmetrically opened openings and a fish reef group. The prefabricated component body is composed of a lower rectangular block and an upper trapezoidal block, the rectangular block is hollow in the middle, and a lower opening rectangular bottom plate is connected, the elevation of the bottom plate meets the design that the water depth under the low tide level is not less than 1 m, and the trapezoidal block is hollow in the middle and the top elevation is not less than the average high tide level; The asymmetric opening includes a first opening and a second opening, which are respectively arranged on different sides of the longitudinal two ends of the rectangular block, and constitute an asymmetric layout without height difference; The longitudinal partition plate is arranged in the cavity of the rectangular block along the dam axis direction, the height of the longitudinal partition plate is consistent with the height of the component, the trend of the longitudinal partition plate starts from the middle position of the first opening, extends through the longitudinal center line, and ends at the middle position of the second opening, so that the cavity is divided into a first channel and a second channel which are independent of each other and have a Z-shaped trend; The transverse partition plates are arranged in the first channel and the second channel, and a plurality of interpenetrating multi-stage buffer pools are formed; the fish reef group is arranged outside the first opening and the second opening.

10. The bio-communication channel of claim 9, wherein: The transverse partition plates in the first channel are arranged from high to low in stages from the first opening to the second opening, and the transverse partition plates in the second channel are arranged from low to high in stages from the first opening to the second opening.

11. The bio-communication channel of claim 9, wherein, The transverse partition plates include main transverse partition plates and auxiliary transverse partition plates, which are arranged alternately; the main transverse partition plates are perpendicular to the inner side wall and the bottom plate of the rectangular block, extend from the inner side wall to close to the longitudinal partition plate, and have a distance of 1.5-2.0 m from the longitudinal partition plate; the auxiliary transverse partition plates are perpendicular to the longitudinal partition plate and the bottom plate, extend from the longitudinal partition plate to the middle of the first channel and the second channel, and have a length of 1.5-2.0 m; the main transverse partition plates and the auxiliary transverse partition plates are arranged at a distance of 1.5-2.0 m, and have a height of 0.8-1.2 m above the bottom plate; the thickness of the longitudinal partition plate is 0.2-0.3 m.

12. The bio-communication channel of claim 9, wherein, The multi-stage buffer pools include ordinary pool rooms and rest pool rooms, the bottom plate of the rest pool room is 0.3-0.5 m deeper than that of the ordinary pool room, and the pool length is 1.5 times that of the ordinary pool room.

13. The bio-communication channel of claim 9, wherein, The trend of the Z-shaped channel is that the longitudinal partition plate is perpendicular to the bottom plate, starts from the middle position of the first opening, extends along the longitudinal center line by 90° after turning at the longitudinal center line to the second opening direction, turns by 90° again at the vertical point of the middle point of the bottom plate of the second opening to the longitudinal center line, and extends to the middle position of the second opening.

14. The bio-communication channel of claim 9, wherein: Toe-shaped structures are arranged on both sides of the bottom plate of the prefabricated component.

Images