Artificial tidal creek system and parameter design method thereof

Abstract

The invention discloses an artificial tidal creek system and a parameter design method thereof, and relates to the technical field of coastal wetland ecological remediation, the artificial tidal creek system comprises a plurality of tidal creeks which are arranged at intervals and are connected with the ocean and the inland, and the artificial tidal creek system is characterized in that each tidal creek comprises a plurality of corners which are sequentially connected from front to back; the mutually connected corners face opposite directions, and the edges, facing the ocean, of the corners extend towards the inland direction and communicate with the edges, facing the inland, of the corners through arcs. According to the tidal creek system, the blocking capacity of the tidal creek system on storm surge can be improved while the water body exchange function of the tidal creek system is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of coastal wetland ecological restoration, and in particular to an artificial tidal ditch system and a parameter design method thereof. Background Art

[0002] Coastal wetlands are a vital component of coastal ecosystems, performing multiple ecological functions, including climate regulation, water purification, and habitat provision. Tidal creek networks, as a crucial component of coastal wetlands, play a crucial role in transporting water, sediment, and nutrients to the wetlands and maintaining water exchange. However, the presence of tidal creek networks also significantly reduces the attenuation of catastrophic long waves, such as storm surges, within wetlands. This is because the greater water depth and lower resistance within tidal creeks allow storm surge energy to propagate rapidly into the wetlands, potentially damaging wetland ecosystems and coastal infrastructure.

[0003] Artificially excavating tidal channels is a common ecological restoration method in coastal wetland restoration projects. Traditional tidal channel design focuses primarily on water exchange and sediment transport, but lacks consideration for storm surge attenuation. Therefore, ensuring tidal channels' water exchange function while enhancing their storm surge resistance has become a key technical challenge in coastal wetland restoration.

[0004] Furthermore, after the design of an artificial tidal gully system is complete, its parameters, including tidal gully density and depth, need to be calculated. Existing methods for calculating tidal gully density are disconnected from the quantification of ecological processes. The fractal characteristics of natural tidal gullies (fractal dimension D) are influenced by sediment-vegetation dynamics, but existing methods fail to link D with ecological variables, resulting in static designs that are unable to adapt to wetland evolution. Existing methods for calculating tidal gully density lead to a conflict between disaster prevention and ecology: high density facilitates water exchange but increases storm surge risk, while low density does the opposite. A quantified "safety density threshold" is needed. Existing methods for calculating tidal gully depth rely on static hydrological calculations (based on the tidal level difference ΔH + E) and ignore the risk of soil instability. Existing methods for calculating tidal gully depth also suffer from a disconnect between biological activity and engineering parameters.

[0005] In view of this, this invention is proposed. Summary of the Invention

[0006] The purpose of the present invention is to address the shortcomings of the prior art and propose an artificial tidal channel system that can increase its ability to block storm surges while ensuring the water exchange function of the tidal channel. In addition, to guide the implementation of the artificial tidal channel system, the present invention also proposes a parameter calculation method for the artificial tidal channel system, which is used to calculate parameters such as tidal channel density and depth in the tidal channel system.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: An artificial tidal channel system includes several tidal channels arranged at intervals and connecting the ocean and the inland. The tidal channels include several corners connected in sequence. The mutually connected corners face opposite directions. The edges of the corners facing the ocean extend inland and are connected to the edges of the corners facing inland through arcs.

[0008] Furthermore, when the wetland is an erosion risk area, the range of the diversion fork angle at the corner is 30°≤θ≤60°; when the water flow in the wetland is close to the critical Froude number, the range of the diversion fork angle at the corner is 30°≤θ≤45°; when the wetland is a siltation area, the range of the diversion fork angle at the corner is 50°≤θ≤60°; when the wetland needs to enhance the storm attenuation capacity, the range of the diversion fork angle at the corner is 60°≤θ≤70°; the diversion fork angle is the angle between the side of the corner extending inland and the side facing inland.

[0009] In order to achieve the above object, the present invention also adopts the following technical solutions: A parameter design method for an artificial tidal channel system, applied to any one of the artificial tidal channel systems provided in the present invention, comprises the following steps: S1: Calculate the initial tidal gully density according to the fractal dimension, and optimize the initial tidal gully density according to the competition intensity coefficient to obtain the final tidal gully density; S2: Calculate the number of tidal gullies based on wetland size, tidal gully length and tidal gully density; S3: Calculate the initial tidal ditch depth based on the intertidal table elevation and the highest tide level, and optimize the initial tidal ditch depth based on the fixed effect coefficient and bioturbation coefficient to obtain the final tidal ditch depth; S4: Calculate the initial tidal creek width based on the tidal creek depth, tidal flow and velocity distribution, and optimize the initial tidal creek width according to the sediment particle size and vegetation density to obtain the final tidal creek width; S5: Calculate the initial tidal gully curvature according to the velocity distribution and the transverse slope of the bend, and correct the initial tidal gully curvature according to the artificial roughness element and the drag coefficient to obtain the final tidal gully curvature; S6: Calculate the number of diversion-return flow units based on the curvature of the tidal creek and the angle of the tidal creek diversion fork.

[0010] Furthermore, the S1 includes the following steps: S11: Determine the initial fractal dimension D0; S12: Calculate the fractal dimension D based on the changes in sediment flux and vegetation cover. The calculation formula is as follows: ; Among them, α and β are weight coefficients, △S is the change in sediment flux, S0 is the original sediment content, and V is the change in vegetation cover; S13: Calculate the initial tidal channel density ρ0 according to the following formula: ; Where C is the regional constant; S14: Calculate the tidal channel density ρ based on competition driving, the calculation formula is as follows: ; Among them, C i is the competition intensity coefficient, Fr is the Froude number, F r,crit is the critical Froude number.

[0011] Furthermore, the step S2 includes the following steps: S21: Calculate the number of tidal gullies M according to the following formula: ; Where ρ is the density of tidal gullies, S is the wetland area, is the length of a single tidal creek.

[0012] Furthermore, the step S3 includes the following steps: S31: Calculate the initial tidal channel depth h0 based on the intertidal platform elevation and the highest tide level. The calculation formula is as follows: ; Where △H is the difference between the highest tide level and the tidal flat elevation, and E is the average tidal range; S32: Calculate the tidal gully depth h based on the fixed effect coefficient and the bioturbation coefficient. The calculation formula is as follows: ; Among them, k1 and k2 are ecological action coefficients, F s is the fixed effect coefficient, B d is the bioturbation coefficient.

[0013] Further, the S4 includes the following steps: S41: Calculate the initial tidal creek width B0 based on the tidal creek depth, design tidal flow, and design flow velocity. The calculation formula is as follows: ; Where Q is the design tidal current, v is the design flow velocity, and h is the depth of the tidal channel; S42: Calculate the tidal gully width B based on sediment particle size and vegetation density using the following formula: ; Among them, γ and λ are fitting coefficients, d is the sediment particle size, d0 is the reference particle size, ρ v is the vegetation density.

[0014] Furthermore, the step S5 includes the following steps: S51: Calculate the initial tidal gully curvature R0 based on the design flow velocity and the transverse slope of the bend. The calculation formula is as follows: ; Among them, v is the design flow velocity, g is the acceleration of gravity, and s is the transverse slope of the curve; S52: Calculate the tidal gully curvature R based on the artificial roughness element and the drag coefficient. The calculation formula is as follows: ; Among them, C d is the drag coefficient, N r is the rough element density.

[0015] Furthermore, the step S6 includes the following steps: S61: Calculate the number of diversion-reflux units N according to the following formula: ; ; in, is the length of a single tidal ditch, R is the curvature of the tidal ditch, θ is the angle of the tidal ditch fork, and △L is 20%~30% of the arc length of the return flow part.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The artificial tidal channel system of the present invention maintains the water exchange and sediment transport functions: at low tide, the geometric shape of the tidal channel can maintain a small flow resistance, ensuring smooth water backflow and avoiding stagnation, thereby maintaining the water exchange and sediment transport functions of the wetland; 2. The artificial tidal channel system of the present invention enhances the storm surge attenuation capacity: through the geometric shape and network structure of the new tidal channel, it can generate greater flow resistance when a storm surge hits, hindering the spread of water into the wetland, thereby significantly enhancing the wetland's storm surge attenuation capacity; 3. The artificial tidal ditch system of the present invention is eco-friendly: suitable wetland vegetation can be planted on both sides of the tidal ditch, which not only enhances the stability of the tidal ditch but also further attenuates the energy of storm surges through the flow-blocking effect of vegetation, thus having significant ecological benefits. 4. In the parameter design method S1 of the artificial tidal channel system of the present invention, the dynamic fractal dimension calculation in S11-S12 uses the sediment flux change (△S) and vegetation coverage (V) as the dynamic input of the fractal dimension D, so that the density basic parameter It has ecological adaptability. The initial density-related fractal feature in S13 uses the fractal dimension D to construct a nonlinear relationship between tidal creek density and wetland area A, reflecting the fractal law of natural tidal creeks. Competition-driven density optimization in S14 introduces the Froude number (Fr) and critical value (Fr,crit) to quantify hydrodynamic risk. The competition intensity coefficient Ci characterizes the inhibitory effect of resource competition between tidal creeks on density. When Fr is high (near-critical flow state), density is actively reduced to suppress the propagation of storm surge energy. 5. In the parameter design method S3 of the artificial tidal channel system of the present invention: in S31, the basic hydrological depth is calculated by calculating the maximum tidal level difference △H and the average tidal range E to ensure the basic tidal flow capacity; in S32, the fixed effect coefficient F is introduced through ecological-mechanical coupling optimization. s Enhance shear strength and inhibit storm surge shear damage; through bioturbation coefficient B d Quantifying the negative correction of depth by burrowing activity to achieve compatibility with ecological disturbance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the layout of the artificial tidal channel system in Example 1; Figure 2 Schematic diagram of water flow in the diversion-return flow tidal channel network structure at high tide; Figure 3 Schematic diagram of water flow in the diversion-return flow tidal channel network structure at low tide; Figure 4 This is a comparison of the water level changes along the two tidal channels at the highest tide level; Figure 5 This is a comparison of the changes in the surface water level along the two tidal creek wetlands at the highest tide level; Figure 6 This is a flow field diagram of the tidal channel system of Example 1 at the highest tide level; Figure 7 This is the flow field diagram of the traditional tidal channel system at the highest tide level; Figure 8 This is a diagram of the sediment accumulation of the tidal gully system in Example 1 after low tide; Figure 9 This is a map of the amount of sediment deposited in the traditional tidal gully system after low tide; Figure 10 This is a flow chart of the parameter design method of the artificial tidal channel system in Example 2. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0019] Example 1: An artificial tidal channel system, such as Figure 1 As shown, it includes several tidal gullies arranged at intervals and connecting the ocean and the inland, and the tidal gullies include several corners connected in sequence. The directions of the mutually connected corners are opposite, and the edges of the corners facing the ocean extend toward the inland direction and are connected to the edges of the corners facing the inland through arcs.

[0020] The artificial tidal channel system of this embodiment adds a forward-extending curve at the corner of the tidal channel to form an internal structure of a diversion-backflow tidal channel network, which can generate a larger flow resistance in one direction and maintain a smaller flow resistance in the opposite direction; Figure 2 、 3 This design can generate greater turbulent energy consumption and greater flow resistance when a storm surge hits (i.e., high tide), hindering the spread of water into the wetland; while at low tide, the geometry of the tidal ditch can maintain a smaller flow resistance, ensuring smooth water backflow and avoiding stagnation.

[0021] The artificial tidal ditch system of this embodiment has the following effects: (1) maintaining the water exchange function and sediment transport function: at low tide, the geometric shape of the tidal ditch can maintain a small flow resistance, ensure the smooth return of water, avoid the formation of stagnation, and thus maintain the water exchange function and sediment transport function of the wetland; (2) enhancing the storm surge attenuation capacity: through the geometric shape and network structure of the new tidal ditch, it can generate a large flow resistance when a storm surge hits, hindering the spread of water into the wetland, thereby significantly enhancing the wetland's storm surge attenuation capacity; (3) eco-friendly: suitable wetland vegetation can be planted on both sides of the tidal ditch, which can not only enhance the stability of the tidal ditch, but also further attenuate the energy of the storm surge through the flow blocking effect of the vegetation, with significant ecological benefits.

[0022] In an optional embodiment, when the wetland is an erosion risk area, the range of the diversion fork angle at the corner is 30°≤θ≤60°; when the water flow in the wetland is close to the critical Froude number, the range of the diversion fork angle at the corner is 30°≤θ≤45°; when the wetland is a siltation area, the range of the diversion fork angle at the corner is 50°≤θ≤60°; when the wetland needs to enhance the storm attenuation capacity, the range of the diversion fork angle at the corner is 60°≤θ≤70°; the diversion fork angle is the angle between the side of the corner extending inland and the side facing inland.

[0023] In order to verify the effectiveness of the method of the first embodiment, a simulation comparison was conducted between the tidal ditch designed in the first embodiment and a traditional tidal ditch. The traditional tidal ditch is a tidal ditch that only has corners but no curved lines extending forward.

[0024] A tidal-storm surge coupled wetland hydrodynamic model was constructed based on the Delft3D hydrodynamic numerical simulation platform. This model includes the equivalent hydrodynamic resistance structure of the intertidal zone and the vegetation belt on the beach, simulating the biogeomorphic coupling effect. The model domain is set as a 1000 m × 1000 m rectangular wetland area, with three parallel tidal channels designed within it. Each channel is 50 m wide and 3 m deep. The bifurcation angle at the intersection of the main tidal channel and the tributary is 45°, and a streamlined transition design is adopted. The initial water level of the model is set to -1.0 m (based on mean sea level), and the suspended sediment concentration is 0.1 kg / m 3 Salt marsh vegetation zones were installed in the intertidal zones on both sides of the tidal creek, consisting of dominant local halophytes (such as Suaeda salsa and Phragmites australis). The offshore terrain of the model domain transitioned to the wetland edge via a gentle slope at a scale of 1:500, ensuring a gentle topographic gradient and avoiding sudden topographic changes in the numerical simulation. A cosine function was used to define the storm surge process at the left open boundary, with a 12-hour period, a high tide level of 1.0 m, and a low tide level of -1.0 m. This simulated periodic water level fluctuations, with high tide levels exceeding the wetland base elevation and low tide levels below it, were observed. In the control group, all simulation conditions remained unchanged, except for the different tidal creek shape.

[0025] Through the above model settings and parameter comparison, a systematic evaluation was conducted on the optimization effect of the tidal channel grid designed using the method in Example 1 on storm surge attenuation, water exchange efficiency, and sediment control. The two systems were compared using three core hydrodynamic parameters: water level dynamic response, velocity field distribution, and sediment accumulation.

[0026] refer to Figure 4 and 5 When the storm surge reaches its highest tide level, the water level responses of the two wetlands are analyzed. The results show that the water levels in the tidal gully and the marsh surface in the wetland system with the tidal gully designed according to the method of Example 1 are lower than those in the traditional tidal gully wetland system, indicating that the tidal gully designed according to the method of Example 1 has a more significant attenuation effect on storm surges.

[0027] refer to Figure 6 and 7 The flow velocity distribution of the two wetlands when the storm surge is at its highest level. The results show that the flow velocity in the tidal ditch designed by the method of Example 1 is significantly lower than the water level in the traditional tidal ditch, indicating that the tidal ditch designed by the method of Example 1 has a more significant effect on slowing the flow velocity.

[0028] refer to Figure 8 and 9 The results show that the amount of sediment accumulation in the wetland system with the tidal ditch designed according to the method of Example 1 is significantly less than that in the traditional tidal ditch wetland system, indicating that the tidal ditch designed according to the method of Example 1 is more effective in preventing sediment accumulation.

[0029] Example 2: A parameter design method for an artificial tidal ditch system is applied to any one of the artificial tidal ditch systems provided in Example 1, and is used to guide the implementation of the artificial tidal ditch system.

[0030] This embodiment provides a parameter design method for an artificial tidal channel system, such as Figure 10 As shown, the following steps are included: S1: Calculate the initial tidal gully density according to the fractal dimension, and optimize the initial tidal gully density according to the competition intensity coefficient to obtain the final tidal gully density; S2: Calculate the number of tidal gullies based on wetland size, tidal gully length and tidal gully density; S3: Calculate the initial tidal ditch depth based on the intertidal table elevation and the highest tide level, and optimize the initial tidal ditch depth based on the fixed effect coefficient and bioturbation coefficient to obtain the final tidal ditch depth; S4: Calculate the initial tidal creek width based on the tidal creek depth, tidal flow and velocity distribution, and optimize the initial tidal creek width according to the sediment particle size and vegetation density to obtain the final tidal creek width; S5: Calculate the initial tidal gully curvature according to the velocity distribution and the transverse slope of the bend, and correct the initial tidal gully curvature according to the artificial roughness element and the drag coefficient to obtain the final tidal gully curvature; S6: Calculate the number of diversion-return flow units based on the curvature of the tidal creek and the angle of the tidal creek diversion fork.

[0031] In an optional embodiment, the S1 includes the following steps: S11: Determine the initial fractal dimension D0; S12: Calculate the fractal dimension D based on the changes in sediment flux and vegetation cover. The calculation formula is as follows: ; Among them, α and β are weight coefficients, △S is the change in sediment flux, S0 is the original sediment content, and V is the change in vegetation cover; S13: Calculate the initial tidal channel density ρ0 according to the following formula: ; Where C is the regional constant; S14: Calculate the tidal channel density ρ based on competition driving, the calculation formula is as follows: ; Among them, C i is the competition intensity coefficient, Fr is the Froude number, F r,crit is the critical Froude number.

[0032] When calculating the density of tidal gullies, it is necessary to consider maintaining the efficiency of water exchange. The density of tidal gullies must meet the material transport needs of the water body inside the wetland and the ocean. Too low a density will lead to insufficient tidal penetration range. In addition, it is also necessary to suppress the propagation of storm surge energy. When the density of tidal gullies is high, a low-resistance channel will be formed, accelerating the invasion of storm surges. Therefore, the density needs to be controlled below the critical value to increase water flow resistance. In addition, it is also necessary to adapt to the dynamic evolution of the wetland.

[0033] Existing methods for calculating tidal creek density are disconnected from the quantification of ecological processes. The fractal characteristics of natural tidal creeks (fractal dimension D) are influenced by sediment-vegetation dynamics, but existing methods fail to link D with ecological variables, resulting in static designs that are unsuitable for wetland evolution. Furthermore, existing methods for calculating tidal creek density lead to a conflict between disaster prevention and ecological priorities: high density facilitates water exchange but increases storm surge risk, while low density does the opposite. A quantified "safe density threshold" is needed.

[0034] In this optional embodiment, the dynamic fractal dimension calculation in S11-S12 uses the sediment flux change (ΔS) and vegetation coverage (V) as dynamic inputs of the fractal dimension D, so that the density-based parameter It has ecological adaptability; the initial density-related fractal characteristics in S13 use the fractal dimension D to construct a nonlinear relationship between tidal creek density and wetland area A, reflecting the fractal law of natural tidal creeks; the competition-driven density optimization in S14 introduces the Froude number (Fr) and critical value (Fr,crit) to quantify hydrodynamic risks, and uses the competition intensity coefficient Ci to characterize the inhibitory effect of resource competition between tidal creeks on density. When Fr is high (near-critical flow state), the density is actively reduced to inhibit the propagation of storm surge energy.

[0035] In an optional embodiment, the step S2 includes the following steps: S21: Calculate the number of tidal gullies M according to the following formula: ; Where ρ is the density of tidal gullies, S is the wetland area, is the length of a single tidal creek.

[0036] In combination with the previous optional embodiment, S1 and S2 use the fractal dimension D and the competition intensity Ci to generate the dynamic density ρ and the quantity M to solve the separation between ecology and disaster prevention.

[0037] In an optional embodiment, the step S3 includes the following steps: S31: Calculate the initial tidal channel depth h0 based on the intertidal platform elevation and the highest tide level. The calculation formula is as follows: ; Where △H is the difference between the highest tide level and the tidal flat elevation, and E is the average tidal range; S32: Calculate the tidal gully depth h based on the fixed effect coefficient and the bioturbation coefficient. The calculation formula is as follows: ; Among them, k1 and k2 are ecological action coefficients, F s is the fixed effect coefficient, B d is the bioturbation coefficient.

[0038] When calculating the depth of the tidal gully, the tidal flow capacity must be guaranteed, and the depth must meet the water transfer requirements of the design tidal flow Q to ensure that the tide can reach the interior of the wetland; in addition, storm surge shear damage must also be considered. During storm surges, the shear force of the water flow increases dramatically, and the depth design must avoid ditch wall collapse.

[0039] The existing method for calculating tidal gully depth ignores the risk of soil instability through static hydrological calculation (based on the tidal level difference △H+E); in addition, the existing method for calculating tidal gully depth also faces the problem of the separation between biological activities and engineering parameters.

[0040] In this optional embodiment, the basic hydrological depth is calculated in S31 to ensure the basic tidal capacity by the highest tidal level difference △H and the average tidal range E; the fixed effect coefficient F is introduced through ecological-mechanical coupling optimization in S32. s Enhance shear strength and inhibit storm surge shear damage; through bioturbation coefficient B d Quantifying the negative correction of depth by burrowing activity to achieve compatibility with ecological disturbance.

[0041] In an optional embodiment, the S4 includes the following steps: S41: Calculate the initial tidal creek width B0 based on the tidal creek depth, design tidal flow, and design flow velocity. The calculation formula is as follows: ; Where Q is the design tidal current, v is the design flow velocity, and h is the depth of the tidal channel; S42: Calculate the tidal gully width B based on sediment particle size and vegetation density using the following formula: ; Among them, γ and λ are fitting coefficients, d is the sediment particle size, d0 is the reference particle size, ρ v is the vegetation density.

[0042] When calculating the width of the tidal creek, it is necessary to match the design tidal flow, that is, the width of the tidal creek must meet the water-passing section requirements of the design tidal flow to ensure water exchange efficiency; in addition, it is also necessary to ensure that abnormal sediment deposition / scouring can be suppressed.

[0043] The existing method for calculating tidal gully width is based on hydraulic formulas and cannot respond to sediment sorting. It ignores the impact of sediment particle size on the critical non-silting flow velocity, resulting in design deviations in the width of the coarse / fine particle zone. In addition, the existing method for calculating tidal gully width makes it difficult to quantify the flow obstruction effect of vegetation.

[0044] In this optional embodiment, the basic hydraulic calculation in S41 guarantees the minimum theoretical width under the design tidal flow; in S42, the width is dynamically adjusted according to the ratio of particle size d to the reference d0 based on sediment-vegetation coupling optimization. If d / d0 > 1 (coarse particles), the channel is widened to reduce shear force to prevent scour; if d / d0 < 1 (fine particles), the channel is narrowed to increase flow rate to prevent siltation; in addition, the width is widened exponentially according to vegetation density, ρ v Increase, B increases significantly, compensating for the flow loss caused by vegetation blockage.

[0045] In combination with the above optional embodiment, S3 and S4 are subjected to bioturbation (B d ) and vegetation (ρ v , F s ) Modify h and B to achieve cross-scale parameter coordination.

[0046] In an optional embodiment, the S5 includes the following steps: S51: Calculate the initial tidal gully curvature R0 based on the design flow velocity and the transverse slope of the bend. The calculation formula is as follows: ; Among them, v is the design flow velocity, g is the acceleration of gravity, and s is the transverse slope of the curve; S52: Calculate the tidal gully curvature R based on the artificial roughness element and the drag coefficient. The calculation formula is as follows: ; Among them, C d is the drag coefficient, N r is the rough element density.

[0047] When calculating the curvature of the tidal creek, it is necessary to ensure enhanced storm surge energy dissipation, that is, the curvature of the tidal creek must support the diversion-return flow unit structure, and consume the storm surge energy through the swirling friction of the water flow in the bend; in addition, it is also necessary to be able to suppress the secondary flow scouring of the bend, that is, the centrifugal force of the bend induces secondary flow under high flow velocity, and the curvature radius of the tidal creek must be made to avoid local scouring of the ditch wall; in addition, it is also necessary to be compatible with artificial energy dissipation structures.

[0048] In this optional embodiment, the basic hydraulic calculation in S51 balances the centrifugal force by the transverse slope s to suppress the secondary flow scour; in S52, the curvature radius is actively reduced (i.e., the curvature is increased) in combination with the artificial structure collaborative correction; the higher roughness element density (Nr is large) makes R significantly smaller than R0, increases the number of bends, extends the flow path, and improves the slewing energy consumption; the drag coefficient (Cd ) quantifies the rough element shape resistance and together with Nr constitutes the energy dissipation enhancement factor.

[0049] In an optional embodiment, the S6 includes the following steps: S61: Calculate the number of diversion-reflux units N according to the following formula: ; ; in, is the length of a single tidal ditch, R is the curvature of the tidal ditch, θ is the angle of the tidal ditch fork, and △L is 20%~30% of the arc length of the return flow part.

[0050] In combination with the previous optional embodiment, S5 and S6 calculate the number of diversion-return flow units N based on the curvature R and the angle θ, convert the parameters into a physical energy dissipation structure, and ultimately unify the ecological function and disaster prevention goals.

[0051] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An artificial tidal channel system, comprising a plurality of tidal channels arranged at intervals and connecting the ocean and the inland, characterized in that: The tidal creek includes a plurality of corners connected in sequence, the directions of the mutually connected corners are opposite, the edges of the corners facing the ocean extend inland and are connected to the edges of the corners facing inland through arcs.

2. An artificial tidal channel system according to claim 1, characterized in that: When the wetland is an erosion risk area, the range of the diversion fork angle of the corner is 30°≤θ≤60°; when the water flow in the wetland is close to the critical Froude number, the range of the diversion fork angle of the corner is 30°≤θ≤45°; when the wetland is a siltation area, the range of the diversion fork angle of the corner is 50°≤θ≤60°; when the wetland needs to enhance the storm attenuation capacity, the range of the diversion fork angle of the corner is 60°≤θ≤70°; the diversion fork angle is the angle between the side of the corner extending inland and the side facing inland.

3. A parameter design method for an artificial tidal channel system, characterized in that: The artificial tidal channel system according to claim 1 or 2 comprises the following steps: S1: Calculate the initial tidal gully density according to the fractal dimension, and optimize the initial tidal gully density according to the competition intensity coefficient to obtain the final tidal gully density; S2: Calculate the number of tidal gullies based on wetland size, tidal gully length and tidal gully density; S3: Calculate the initial tidal ditch depth based on the intertidal table elevation and the highest tide level, and optimize the initial tidal ditch depth based on the fixed effect coefficient and bioturbation coefficient to obtain the final tidal ditch depth; S4: Calculate the initial tidal creek width based on the tidal creek depth, tidal flow and velocity distribution, and optimize the initial tidal creek width according to the sediment particle size and vegetation density to obtain the final tidal creek width; S5: Calculate the initial tidal gully curvature according to the velocity distribution and the transverse slope of the bend, and correct the initial tidal gully curvature according to the artificial roughness element and the drag coefficient to obtain the final tidal gully curvature; S6: Calculate the number of diversion-return flow units based on the curvature of the tidal creek and the angle of the tidal creek diversion fork.

4. The parameter design method of an artificial tidal channel system according to claim 3, characterized in that: The S1 comprises the following steps: S11: Determine the initial fractal dimension D0; S12: Calculate the fractal dimension D based on the changes in sediment flux and vegetation cover. The calculation formula is as follows: ； Among them, α and β are weight coefficients, △S is the change in sediment flux, S0 is the original sediment content, and V is the change in vegetation cover; S13: Calculate the initial tidal channel density ρ0 according to the following formula: ； Where C is the regional constant; S14: Calculate the tidal channel density ρ based on competition driving, the calculation formula is as follows: ； Among them, C i is the competition intensity coefficient, Fr is the Froude number, F r,crit is the critical Froude number.

5. The parameter design method of an artificial tidal channel system according to claim 3, characterized in that: The S2 comprises the following steps: S21: Calculate the number of tidal gullies M according to the following formula: ； Where ρ is the density of tidal gullies, S is the wetland area, is the length of a single tidal creek.

6. The parameter design method of an artificial tidal channel system according to claim 3, characterized in that: The S3 comprises the following steps: S31: Calculate the initial tidal channel depth h0 based on the intertidal platform elevation and the highest tide level. The calculation formula is as follows: ； Where △H is the difference between the highest tide level and the tidal flat elevation, and E is the average tidal range; S32: Calculate the tidal gully depth h based on the fixed effect coefficient and the bioturbation coefficient. The calculation formula is as follows: ； Among them, k1 and k2 are ecological action coefficients, F s is the fixed effect coefficient, B d is the bioturbation coefficient.

7. The parameter design method of an artificial tidal channel system according to claim 3, characterized in that: The S4 comprises the following steps: S41: Calculate the initial tidal creek width B0 based on the tidal creek depth, design tidal flow, and design flow velocity. The calculation formula is as follows: ； Where Q is the design tidal current, v is the design flow velocity, and h is the depth of the tidal channel; S42: Calculate the tidal gully width B based on sediment particle size and vegetation density using the following formula: ； Among them, γ and λ are fitting coefficients, d is the sediment particle size, d0 is the reference particle size, ρ v is the vegetation density.

8. The parameter design method of an artificial tidal channel system according to claim 3, characterized in that: The S5 comprises the following steps: S51: Calculate the initial tidal gully curvature R0 based on the design flow velocity and the transverse slope of the bend. The calculation formula is as follows: ； Among them, v is the design flow velocity, g is the acceleration of gravity, and s is the transverse slope of the curve; S52: Calculate the tidal gully curvature R based on the artificial roughness element and the drag coefficient. The calculation formula is as follows: ； Among them, C d is the drag coefficient, N r is the rough element density.

9. The parameter design method of an artificial tidal channel system according to claim 3, characterized in that: The S6 comprises the following steps: S61: Calculate the number of diversion-reflux units N according to the following formula: ； ； in is the length of a single tidal ditch, R is the curvature of the tidal ditch, θ is the angle of the tidal ditch fork, and △L is 20%~30% of the arc length of the return flow part.

Images