Ecological groynes for controlling rainfall runoff pollution into rivers and their deployment methods

Abstract

This invention relates to an ecological groynes system for controlling pollution from rainwater runoff flowing into rivers and its deployment method. The deployment method involves selecting a study area, obtaining the storage capacity V of the ecological groynes area through empirical formulas or SWMM model simulation, calculating the length S of the ecological groynes area, determining the parameter range of the ecological groynes system, and simulating the specific values ​​of the groynes' angle, relative length, spacing, and number of groynes. This invention utilizes the receiving river to perform in-situ storage and purification of rainwater runoff, intercepting and controlling pollution from rainwater runoff at stormwater outlets, thereby mitigating the impact of pollutants carried by rainwater runoff on the water environment of the receiving river.

Description

Technical Field

[0001] This invention relates to an ecological groynes and their deployment method for controlling pollution from rainfall runoff flowing into rivers, belonging to the technical field of river pollution control and river regulation. Background Technology

[0002] Initial rainfall runoff is often characterized by large fluctuations in volume and severe pollution, impacting the receiving river's aquatic environment. Initial rainfall runoff pollution has become one of the most pressing issues in urban water environment management. Rainfall runoff control measures are mainly divided into source control, process control, and end-of-pipe control. With the construction of sponge cities, rainfall runoff has been effectively controlled at the source and during its flow. However, in some urban built-up areas, the construction of sponge city measures is limited, leading to the accumulation of pollution at the end of the runoff flow, necessitating end-of-pipe treatment measures. Currently, however, end-of-pipe treatment measures are lacking, failing to guarantee that the water environment will not be damaged after rainfall runoff enters rivers.

[0003] Groynes, as a common hydraulic structure, are widely used to protect riverbanks from erosion. Furthermore, groynes can "constrain water flow and attack sediment," creating deep scouring channels in the downstream area and slowing down sediment deposition in the downstream area. Groynes also create diverse riverbed morphologies, providing rich habitats for aquatic organisms. Current research has found that groynes can retain pollutants and prevent their spread. For example, a method for improving the nutrient retention potential of streams and ditches, disclosed in patent number 202110806081.4, alters the stream's flow pattern by setting up a group of groynes on one side of the stream channel, creating numerous small eddies and a flow velocity distribution with varying speeds, thus extending the hydraulic residence time of nutrients in the stream. The unique flow structure and material distribution in groyne areas indicate that the potential of groynes in pollution control has not yet been fully explored. Rationally utilizing groynes to control river pollution and fully leveraging their function in water environment management provides new ideas for river water environment governance. Summary of the Invention

[0004] To address the aforementioned problems, this invention discloses an ecological groynes group for controlling pollution from rainfall runoff flowing into rivers and its deployment method, the specific technical solution of which is as follows:

[0005] A method for deploying an ecological groynes for controlling pollution from rainwater runoff flowing into rivers includes the following steps:

[0006] Step 1: Select the study area and obtain the storage capacity V of the ecological groyne area through empirical formulas or SWMM model simulation. Based on the storage capacity, river depth and width, preliminarily calculate the length S of the ecological groyne area. The calculation formula is as follows:

[0007]

[0008] S represents the length of the ecological groynes area, in meters; h represents the depth of the receiving river, in meters; and B represents the width of the river channel, in meters.

[0009] Step 2: Determine the parameter range for the ecological groynes group:

[0010] 2.1: The ecological groynes are arranged alternately along both banks of the river, with the height of the groynes consistent with the normal water level of the river, reducing the impact on the river's flood discharge during the flood season;

[0011] 2.2: The groyne angle refers to the angle between the groyne and the upstream riverbank. The groyne angle θ can be either straight (θ=90°) or upward (θ<90°). In this case, the backflow area behind the ecological groyne is larger than that of a downward groyne (θ>90°), providing a longer hydraulic residence time for pollutant retention and purification.

[0012] 2.3: The relative length of a groyne refers to the ratio of the vertical projection L of the groyne onto the river width to the river width B. The relative length of a groyne has a significant impact on the area of ​​the backflow zone behind the groyne; the relative length of an ecological groyne should be within the range of 1 / 3 to 3 / 5.

[0013] 2.4: Based on engineering experience, the spacing D of groynes is generally 1.5-2.5 times the length of the groynes;

[0014] 2.5: The number of groynes, n, is calculated using the length S of the groyne area and the spacing D between the groynes. The calculation formula is as follows:

[0015]

[0016] Step 3: Simulation calculations yield the specific values ​​for the spur angle, relative spur length, spur spacing, and number of spurs in the ecological groynes group:

[0017] First, the topographic conditions and water quality and quantity conditions of the receiving river are investigated, and parameter combinations are selected within the given range of groynes parameters. The boundary conditions and initial conditions for the simulation are determined, the model is constructed, and the mesh is generated.

[0018] The simulation calculation uses fluid dynamics theory to construct a hydrodynamic-water quality numerical model. Grids with different parameter combinations are imported into the model for calculation to obtain the hydrodynamic and pollutant migration and transformation in the ecological groynes area. By comparing the stability of the water flow and the removal of pollutants, the parameter combination that provides the best stability of water flow, suspended solids settling, and pollutant retention is selected.

[0019] Furthermore, a preliminary investigation was conducted on the regional pipeline network and underlying surface to determine the complexity of the regional runoff generation and confluence process. Based on this, the calculation method for the regulation and storage volume V of the ecological groynes group region was selected.

[0020] If the regional pipeline network is simple and the underlying surface is relatively uniform, the empirical formula method can be directly used for calculation. However, this method requires further investigation into the region's rainfall patterns and underlying surface distribution. The design rainfall H is selected based on a two-year return period rainfall intensity for the study area, taking into account the comprehensive rainfall-runoff index. The runoff index is calculated based on the proportion of each underlying surface, with reference to the "Technical Guidelines for Sponge City Construction - Construction of Low Impact Development Rainwater Systems (Trial)".

[0021]

[0022] In the formula: V is the storage capacity, m 3 H represents the design rainfall, in mm; The comprehensive rainfall-runoff coefficient is given by F, where F is the catchment area (hm²). 2 ;

[0023] If the regional pipe network is complex and the underlying surface is diverse, the SWMM model is selected for simulation calculation. The SWMM model simulation requires obtaining the topographic slope, rainfall data, permeability coefficient, surface runoff generation and runoff process parameters, pipe network runoff process parameters, and surface pollutant accumulation and scouring process parameters of the study area. First, it is necessary to generalize the sub-catchment areas of the study area, dividing the large area into some smaller hydrological units that directly discharge surface rainfall runoff to a single discharge point. The parameters are then input into the SWMM model to construct the SWMM model of the study area. Based on the sensitivity of relevant parameters determined by the modified Morse classification screening method, parameters with higher sensitivity are identified. The model parameters are calibrated using measured water quality and quantity data to determine the model parameters. The SWMM model is then used for simulation analysis to obtain the rainwater outfall flow and pollution load, and to determine the rainwater interception and storage volume.

[0024] The normal water level of a river in step 2.1 refers to the elevation value of a river or lake that is equal to or exceeds the water level at a certain location over a long period of time, which is obtained after observing the water level at a certain location over a long period of time.

[0025] Furthermore, the governing equations of the hydrodynamic-water quality model constructed in step three are as follows:

[0026] (1) Hydrodynamic control equations

[0027]

[0028]

[0029] Equation (4) is the continuity equation for water flow, where x i For the Cartesian x, y, z directions, u iThe velocity represents the flow velocity in the corresponding direction; Equation (5) is the momentum equation, where g is the acceleration due to gravity, ρ is the density of water, v is the kinematic viscosity, and p is the water pressure. For Reynolds stress term; due to The unknown is solved using the turbulence model κ-ε, and its governing equations include:

[0030]

[0031] In the formula, κ represents turbulent kinetic energy, ε represents the energy dissipation rate, and G represents the turbulent kinetic energy generation term; G is calculated as follows:

[0032]

[0033]

[0034] In the formula, C μ C1, C2, σ κ and σ ε All are constants;

[0035] (2) Governing equations for mass migration and transformation processes

[0036]

[0037] In the formula, C represents the concentration of the pollutant, and D... i S is the diffusion coefficient in the corresponding direction. L For the pollution source term, K is the linear decay coefficient of the pollutants;

[0038] The main consideration for suspended matter is its migration process, and its governing equation is:

[0039]

[0040] In the formula, S, S * ε represents the concentration of suspended solids in the water flow and the saturated concentration of suspended solids in the water flow. s ω is the turbulent diffusion coefficient; ω is the settling velocity of suspended matter; α is the recovery saturation coefficient of suspended matter.

[0041] Based on the hydrodynamic and pollutant distribution data of the ecological groynes area output by the model, a hydrodynamic and pollutant distribution map of the ecological groynes area was drawn. The combination of groynes parameters that yielded the highest water flow stability (p) and pollutant removal rate (q) under different groynes angles, relative groynes lengths, groynes spacing, and the number of groynes was compared.

[0042]

[0043] In the formula, v 入 v 出 c represents the flow velocity at the inlet and outlet of the ecological groyne. 入 c出 These represent the pollutant concentrations at the inlet and outlet of the ecological groynes, respectively.

[0044] The ecological groynes used for controlling pollution from rainwater runoff into rivers, as described above, are obtained by the deployment method of the ecological groynes used for controlling pollution from rainwater runoff into rivers.

[0045] Furthermore, this includes several ecological groynes staggered along both banks of the river, located downstream of the river's stormwater outfalls.

[0046] Furthermore, the ecological groyne includes pine stakes, bamboo strips, tarpaulin, filler soil, gravel, emergent plants planted on top, and iron nails. The outermost layer of the ecological groyne is secured with pine stakes, which are driven into the ground in rows along the perimeter of the groyne. The pine stakes are driven into the ground to a depth of 1 / 2 the height of the groyne, and the diameter of the pine stakes is approximately 5-10 cm. The inner layer of the pine stakes is reinforced with bamboo strips, which are also driven into the ground in rows to a depth of 1 / 3 the height of the groyne. The width of the bamboo strips is approximately 4- Bamboo strips are 8cm thick and more than 0.8cm thick. The inner layer of the bamboo strips is insulated with colored tarpaulin to prevent soil loss inside the groyne. The upper end of the tarpaulin is fixed to the bamboo strips with iron nails, one nail every 3-4 bamboo strips. The lower end of the tarpaulin is buried under the fill soil for fixation. The fill soil can be dried on-site using bottom mud, with the moisture content controlled at about 40-60%. The fill soil is compacted and filled into the groyne. A 2-3cm thick layer of gravel is piled on top of the fill soil. Local emergent plants with landscape effect are planted on top of the fill soil.

[0047] The beneficial effects of this invention are:

[0048] This invention utilizes ecological groynes in situ to control pollution from rainwater runoff flowing into urban rivers. This not only buffers large volumes of rainwater runoff but also promotes the rapid sedimentation of suspended matter and the retention of dissolved pollutants in the runoff, thereby reducing the impact of rainwater runoff on the receiving river's aquatic environment.

[0049] This invention presents an ecological groyne structure that is simple in structure, uses environmentally friendly materials, does not cause secondary pollution to the river water environment, and has certain landscape benefits. The layout of the ecological groyne network, calculated using numerical models, allows for more accurate and efficient control of rainfall runoff pollution, reducing the waste caused by excessive groyne deployment and the risk of rainfall runoff pollution to the river water environment due to insufficient deployment. This invention utilizes the receiving river to perform in-situ regulation and purification of rainfall runoff, alleviating to some extent the problems of traditional regulation facilities in urban built-up areas, such as land scarcity and high investment costs. By intercepting and controlling rainfall runoff pollution at stormwater outfalls, the impact of pollutants carried by rainfall runoff on the receiving river water environment is reduced. Simultaneously, the groyne network can adjust hydrodynamic conditions, reducing the impact of large water volumes on the river's aquatic ecosystem. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the ecological groynes layout.

[0051] Figure 2 This is a top view of the ecological groynes of the present invention.

[0052] Figure 3 for Figure 2 A cross-sectional view along the AA direction.

[0053] List of reference numerals in the attached diagram: 1—Pine stake, 2—Bamboo strip, 3—Rainbow strip, 4—Soil filling, 5—Gravel, 6—Emerging plant, 7—Iron nail. Detailed Implementation

[0054] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0055] This ecological groyne system, used for controlling pollution from rainwater runoff flowing into the river, comprises several groynes staggered along both banks of the river, located downstream of the river's stormwater outfalls. Each groyne consists of pine stakes, bamboo strips, tarpaulin, filler soil, gravel, emergent plants, and nails. The outermost layer of the groyne is secured with pine stakes, driven into the ground in rows along the perimeter to a depth of half the groyne's height. The pine stakes are approximately 5-10 cm in diameter. The inner layer of the groyne is reinforced with bamboo strips, also driven into the ground in rows to a depth of one-third the groyne's height. The bamboo strips are approximately 4-8 cm wide. The bamboo strips are thicker than 0.8cm. The inner layer of the bamboo strips is insulated with colored tarpaulin to prevent soil loss inside the groyne. The upper end of the tarpaulin is fixed to the bamboo strips with iron nails, one nail every 3-4 bamboo strips. The lower end of the tarpaulin is buried under the fill soil for fixation. The fill soil can be dried on-site using bottom mud, with the moisture content controlled at about 40-60%. The fill soil is compacted and filled into the groyne. A 2-3cm layer of gravel is piled on top of the fill soil. Local emergent plants with landscape effect are planted on top of the fill soil.

[0056] First, specific parameters of the ecological groynes area are determined based on a method for deploying ecological groynes for controlling pollution from rainwater runoff flowing into rivers.

[0057] Combination Figure 1 The specific method for deploying ecological groynes for controlling pollution from rainwater runoff flowing into rivers according to this invention is as follows:

[0058] Step 1: Based on the rainfall and underlying surface conditions of the surveyed area, the storage capacity of the ecological groyne area is obtained through simulation using empirical formulas or SWMM models. The length of the ecological groyne area is then preliminarily calculated based on the storage capacity and river depth. The calculation formula is as follows:

[0059]

[0060]

[0061] In the formula: V is the design storage capacity, m 3 H represents the design rainfall, in mm; The comprehensive rainfall-runoff coefficient is given by F, where F is the catchment area (hm²). 2 S is the length of the ecological groynes area, in meters; h is the depth of the receiving river, in meters; B is the width of the river channel, in meters.

[0062] Step Two: Determine the parameter range for ecological groynes. For example... Figure 1 As shown, ecological groynes are staggered along both banks of the river. The height of the groynes matches the normal water level of the river, reducing the impact on flood discharge during the flood season. The angle θ is generally chosen to be either upright (θ=90°) or upward (θ<90°), in which case the backflow area behind the ecological groynes is larger than that of downward (θ>90°), providing more hydraulic retention time for pollutants. The relative length of the groynes has a significant impact on the area of ​​the backflow area, and the relative length of ecological groynes is in the range of 1 / 3 to 3 / 5. Based on engineering experience, the spacing between groynes is generally 1.5 to 2.5 times the length of the groynes.

[0063] Step 3: After determining the length of the groyne area, select parameters within the given layout parameter range for orthogonal combination simulation. The parameter combinations selected in this embodiment are shown in the table below.

[0064] Table 1. Structural Parameters and Layout of Groynes

[0065]

[0066] Orthogonal combinations of the parameters yield 27 possible combinations. The number of groynes is calculated using the length of the groyne region and the spacing between groynes, using the following formula:

[0067]

[0068] The optimal combination of ecological groynes was determined by analyzing the parameters and constructing a hydrodynamic-water quality model based on the topographic conditions of the receiving river. The governing equations of the constructed hydrodynamic-water quality model are as follows:

[0069] (1) Hydrodynamic control equations

[0070]

[0071] Equation 4 is the continuity equation for water flow, where x i For the Cartesian x, y, z directions, u iThis represents the flow velocity in the corresponding direction. Equation 5 is the momentum equation, where g is the acceleration due to gravity, ρ is the density of water, v is the kinematic viscosity, and p is the water pressure. This is the Reynolds stress term. Because... The unknown is solved using the turbulence model κ-ε, and its governing equations include:

[0072]

[0073] In the formula, κ represents turbulent kinetic energy, ε represents the energy dissipation rate, and G represents the turbulent kinetic energy generation term. G is calculated as follows:

[0074]

[0075] In the formula, C μ C1, C2, σ κ and σ ε All are constants.

[0076] (2) Governing equations for mass migration and transformation processes

[0077]

[0078] In the formula, C represents the concentration of the pollutant, and D... i S is the diffusion coefficient in the corresponding direction. L For the pollution source term, K is the linear decay coefficient of the pollutants.

[0079] Suspended matter is mainly a migration process, and its governing equation is:

[0080]

[0081] In the formula, S, S * ε represents the concentration of suspended solids in the water flow and the saturated concentration of suspended solids in the water flow. s ω is the turbulent diffusion coefficient; ω is the settling velocity of suspended matter; α is the recovery saturation coefficient of suspended matter.

[0082] Based on the hydrodynamic and pollutant distribution data of the ecological groynes area output by the model, a hydrodynamic and pollutant distribution map of the ecological groynes area was drawn. The combination of groynes parameters that yielded the highest water flow stability (p) and pollutant removal rate (q) under different groynes angles, relative groynes lengths, groynes spacing, and the number of groynes was compared.

[0083]

[0084] In the formula, v 入 v 出 c represents the flow velocity at the inlet and outlet of the ecological groyne. 入 c 出 These represent the pollutant concentrations at the inlet and outlet of the ecological groynes, respectively.

[0085] Based on the hydrodynamic-water quality model constructed above, the water flow and pollutant migration and transformation under different combinations of layout parameters are simulated and calculated to determine the layout parameters of the ecological groynes.

[0086] Once the specific parameters of the groynes are determined, individual groynes can be constructed. For example... Figure 2-3 As shown, an ecological groyne structure for controlling pollution from rainwater runoff flowing into a river includes pine stakes 1, bamboo strips 2, tarpaulin 3, fill soil 4, gravel 5, emergent plants 6, and nails 7. The outermost layer of the ecological groyne is secured with pine stakes 1, which are driven into the ground in rows along the perimeter of the groyne to a depth of 1 / 2 the height of the groyne. The diameter of the pine stakes 1 is approximately 5 cm. The inner layer of the pine stakes 1 is reinforced with bamboo strips 2, which are also driven into the ground in rows to a depth of 1 / 3 the height of the groyne. The width of the bamboo strips 2 is approximately 5 cm, and the thickness is greater than 0.8 cm. The inner layer of the bamboo strips 2 is insulated with tarpaulin 3 to prevent soil erosion within the groyne. The upper end of the tarpaulin 3 is fixed to the bamboo strips 2 with nails 7, one nail every 3-4 bamboo strips. The lower end of the tarpaulin 3 is buried under fill soil 4 for fixation. The fill soil 4 can be dried on-site using subsoil, with the moisture content controlled at approximately 40-60%. The fill soil 4 is compacted and filled into the groynes, and a 2-3cm layer of gravel 5 is piled on top. Local emergent aquatic plants 6 with aesthetic appeal, such as canna lilies and loosestrife, are planted on top of the fill soil 4.

[0087] The following is an example of a specific application of this patent.

[0088] An experimental ecological groynes were constructed within the landscape wetland of the Yixing urban wastewater resource concept plant. This landscape wetland is located in a low-lying area, and nearly half of the plant's rainwater collects here. The total area of ​​the concept plant is approximately 2.5 hectares. 2 The underlying surface mainly consists of rooftops, roads, and green spaces, with the specific proportions shown in Table 2. Since the underlying surface of the concept plant area is relatively simple and the area is small, the empirical formula method is chosen to calculate the storage capacity V.

[0089] Table 2. Percentage of each underlying surface and runoff coefficient

[0090]

[0091] The weighted average rainfall-runoff coefficient for this region, calculated from the table above, is 0.31. The design rainfall is based on a two-year return period rainfall intensity in Yixing City, with the rainfall in the first 30 minutes taken as the design rainfall. The storage capacity V, calculated using Formula 1, is 50 m³. 3 The wetland has an average depth of 0.4m and an average width of 3.5m. According to Formula 2, the length of the ecological groyne area is 35.8m.

[0092] After determining the length of the groynes, parameters are selected within the given layout parameter range for orthogonal combination simulation. The parameter combinations selected in this embodiment are shown in the table below.

[0093] Table 3. Parameter Combination Table for Ecological Groynes

[0094]

[0095]

[0096] Based on the hydrodynamic and pollutant distribution data of the ecological groynes output by the model, hydrodynamic and pollutant distribution maps of the ecological groynes area were plotted. The optimal combination of groynes parameters (angle of inclination, relative length, spacing, and number of groynes) was compared to obtain the highest water flow stability (p) and pollutant removal rate (q) in the ecological groynes area. Finally, the water flow stability (p) and the levels of suspended solids (p) and NH4+ (q) were compared when the groyne angle was 60°, the relative length was 3 / 5, the spacing was 4.20m, and the number of groynes was 8. + The overall removal rate of TN, TP and COD is the best.

[0097] Table 4. Effects of Ecological Groynes

[0098]

[0099] Based on the above-described preferred embodiments of the present invention, and through the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of the present invention.

Claims

1. A method for deploying ecological groynes for controlling pollution from rainwater runoff flowing into rivers, characterized in that, Includes the following steps: Step 1: Select the study area and obtain the storage capacity V of the ecological groyne area through empirical formulas or SWMM model simulation. Based on the storage capacity, river depth and width, preliminarily calculate the length S of the ecological groyne area. The calculation formula is as follows: In the formula, S is the length of the ecological groyne area, in meters; h is the depth of the receiving river, in meters; B is the width of the river channel, in meters. Step 2: Determine the parameter range for the ecological groynes group: 2.1: The ecological groynes are arranged alternately along both banks of the river, and the height of the groynes is consistent with the normal water level of the river; 2.2: The groyne angle θ should be either a straight groyne (θ=90°) or an upward groyne (θ<90°); 2.3: The relative length of a groynes refers to the ratio of the vertical projection L of the groynes onto the river width to the river width B. The relative length of a groynes has a significant impact on the area of ​​the backflow zone behind the groynes. The relative length of an ecological groynes should be in the range of 1 / 3 to 3 / 5. 2.4: Based on engineering experience, the spacing D of ecological groynes should be 1.5-2.5 times the length of the groynes. 2.5: The number of groynes, n, is calculated using the length S of the ecological groyne area and the spacing D between the groynes. The calculation formula is as follows: Step 3: Simulation calculations yield the specific values ​​for the spur angle, relative spur length, spur spacing, and number of spurs in the ecological groynes group: First, the topographic conditions and water quality and quantity conditions of the receiving river are investigated, and parameter combinations are selected within the given range of groynes parameters. The boundary conditions and initial conditions for the simulation are determined, the model is constructed, and the mesh is generated. The simulation calculation uses fluid dynamics theory to construct a hydrodynamic-water quality numerical model. Grids with different parameter combinations are imported into the model for calculation to obtain the hydrodynamic and pollutant migration and transformation in the ecological groynes area. By comparing the stability of the water flow and the removal of pollutants, the parameter combination with the best water flow stability, suspended solids settling, and pollutant retention effect is selected. Based on the hydrodynamic and pollutant distribution data of the ecological groynes area output by the model, a hydrodynamic and pollutant distribution map of the ecological groynes area was drawn. The combination of groynes parameters that yielded the highest water flow stability (p) and pollutant removal rate (q) under different groynes angles, relative groynes lengths, groynes spacing, and the number of groynes was compared. In the formula, v 入 v 出 c represents the flow velocity at the inlet and outlet of the ecological groyne. 入 c 出 These represent the pollutant concentrations at the inlet and outlet of the ecological groynes, respectively.

2. The method for deploying ecological groynes for controlling river runoff pollution according to claim 1, characterized in that, A preliminary survey of the regional pipeline network and underlying surface was conducted to assess the complexity of the regional runoff generation and confluence process. Based on this, the method for calculating the regulation and storage volume V of the ecological groynes group region was selected. If the regional pipeline network is simple and the underlying surface is relatively uniform, the empirical formula method can be directly used for calculation. However, this method requires further investigation into the region's rainfall patterns and underlying surface distribution. The design rainfall H is selected based on a two-year return period rainfall intensity for the study area, taking into account the comprehensive rainfall-runoff index. Calculations are based on the proportion of each underlying surface: In the formula, V is the storage capacity, m 3 H represents the design rainfall, in mm; The comprehensive rainfall-runoff coefficient is given by F, where F is the catchment area (hm²). 2 ; If the regional pipe network is complex and the underlying surface is diverse, the SWMM model is selected for simulation calculation. The SWMM model simulation requires obtaining the topographic slope, rainfall data, permeability coefficient, surface runoff generation and runoff process parameters, pipe network runoff process parameters, and surface pollutant accumulation and scouring process parameters of the study area. First, it is necessary to generalize the sub-catchment areas of the study area, dividing the large area into some smaller hydrological units that directly discharge surface rainfall runoff to a single discharge point. The parameters are then input into the SWMM model to construct the SWMM model of the study area. Based on the sensitivity of relevant parameters determined by the modified Morse classification screening method, parameters with higher sensitivity are identified. The model parameters are calibrated using measured water quality and quantity data to determine the model parameters. The SWMM model is then used for simulation analysis to obtain the rainwater outfall flow and pollution load, and to determine the rainwater interception and storage volume.

3. The method for deploying ecological groynes for controlling river runoff pollution according to claim 1, characterized in that, The governing equations of the hydrodynamic-water quality model constructed in step three are as follows: (1) Hydrodynamic control equations Equation (4) is the continuity equation for water flow, where x i For the Cartesian x, y, z directions, u i The velocity represents the flow velocity in the corresponding direction; Equation (5) is the momentum equation, where g is the acceleration due to gravity, ρ is the density of water, v is the kinematic viscosity, and p is the water pressure. For Reynolds stress term; due to The unknown is solved using the k-ε turbulence model, whose governing equations include: In the formula, k is the turbulent kinetic energy, ε is the energy dissipation rate, and G is the turbulent kinetic energy generation term; G is calculated as follows: In the formula, C μ C1, C2, σ κ and σ ε All are constants; (2) Governing equations for mass migration and transformation processes In the formula, C represents the concentration of the pollutant, and D... i S is the diffusion coefficient in the corresponding direction. L For the pollution source term, K is the linear decay coefficient of the pollutants; The main consideration for suspended matter is its migration process, and its governing equation is: In the formula, S, S * ε represents the concentration of suspended solids in the water flow and the saturated concentration of suspended solids in the water flow. s ω is the turbulent diffusion coefficient; ω is the settling velocity of suspended matter; α is the recovery saturation coefficient of suspended matter.

4. An ecological groynes for controlling pollution from rainwater runoff into rivers, obtained by the deployment method of the ecological groynes for controlling pollution from rainwater runoff into rivers as described in any one of claims 1-3.

5. The ecological groynes for controlling river runoff pollution according to claim 4, characterized in that, It includes several ecological groynes staggered along both banks of the river, located downstream of the river's stormwater outfalls.

6. The ecological groynes for controlling river runoff pollution according to claim 4, characterized in that, The ecological groyne consists of pine stakes, bamboo strips, tarpaulin, filler soil, gravel, emergent plants, and nails. The outermost layer of the groyne is secured with pine stakes, which are driven into the ground in rows along the perimeter to a depth of half the groyne's height. The pine stakes are 5-10cm in diameter. The inner layer of the pine stakes is reinforced with bamboo strips, which are also driven into the ground in rows to a depth of one-third the groyne's height. The bamboo strips are 4-8cm wide. The bamboo strips are thicker than 0.8cm. The inner layer of the bamboo strips is insulated with colored tarpaulin to prevent soil loss inside the groyne. The upper end of the tarpaulin is fixed to the bamboo strips with iron nails, one nail every 3-4 bamboo strips. The lower end of the tarpaulin is buried under the fill soil for fixation. The fill soil can be dried on-site using bottom mud, with the moisture content controlled at 40-60%. The fill soil is compacted and filled into the groyne. A 2-3cm layer of gravel is piled on top of the fill soil. Local emergent plants with landscape effect are planted on top of the fill soil.

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