Ecological spur dike group for runoff pollution control of rainfall in river and layout method of ecological spur dike group

Abstract

The invention relates to an ecological spur dike group for in-river rainfall runoff pollution control and a layout method thereof, and the layout method comprises the steps: selecting a research area, obtaining the regulation and storage volume V of an ecological spur dike area through an empirical formula or SWMM model simulation, calculating the length S of the ecological spur dike area, and determining the parameter range of the ecological spur dike group. And carrying out simulation calculation to obtain specific values of the picking angle, the relative dam length, the dam spacing and the spur dike number of the ecological spur dike group. The receiving river is used for carrying out in-situ regulation, storage and purification on the rainfall runoff, the rainfall runoff pollution is intercepted and controlled at the rainwater outlet, and the influence of pollutants carried by the rainfall runoff on the water environment of the receiving river is reduced.

Description

Technical Field

[0001] The invention relates to an ecological spur dike group for controlling pollution of rainfall runoff entering a river and a laying method thereof, belonging to the technical field of river pollution control and river channel regulation. Background Art

[0002] Initial rainwater often has the characteristics of large fluctuations in water volume and serious pollution. Rainfall runoff into rivers has an impact on the water environment of receiving rivers. Initial rainwater runoff pollution has become one of the main problems that need to be solved in urban water environment management. The management measures for rainfall runoff are mainly divided into source control, process control and terminal control. With the construction of sponge cities, rainfall runoff has been effectively controlled at the source and in the process. The construction of sponge measures in some urban built-up areas is restricted, and rainfall runoff pollution converges at the end, which urgently needs terminal treatment measures to control it. However, the current terminal treatment measures are lacking, and it is impossible to ensure that the water environment is not damaged after rainfall runoff enters the river.

[0003] As a common hydraulic structure, spur dikes are widely used to protect riverbanks from scouring. In addition, spur dikes can also "restrain water and attack sand". The water flow velocity in the area behind the dam is high, forming a deep scouring groove; the flow velocity in the dam field area is slow, which promotes siltation. Spur dikes make rivers form diverse riverbed forms and provide a rich habitat environment for aquatic organisms. At present, studies have found that spur dikes can retain pollutants and prevent pollutants from spreading. For example, a method for regulating and controlling the nutrient retention potential of stream ditches published with patent number 202110806081.4 can change the stream flow morphology by setting and regulating a single-side spur dike structure group on the stream channel, forming many small vortices and a flow velocity layout with fast and slow flow rates, which prolongs the hydraulic retention time of nutrients in the stream. The special water flow structure and material distribution in the spur dike area indicate that the potential of spur dikes in pollution control has not yet been explored. Reasonable use of spur dikes to control river pollution and give full play to the function of spur dikes in water environment management can provide new ideas for river water environment management. Summary of the invention

[0004] In order to solve the above problems, the present invention discloses an ecological spur dike group and its layout method for controlling pollution of rainfall runoff entering a river. The specific technical scheme is as follows:

[0005] A method for laying out an ecological spur dike group for controlling pollution of rainfall runoff entering a river comprises the following steps:

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

[0007]

[0008] S is the length of the ecological spur dike area, m; h is the depth of the receiving river, m; B is the width of the river channel, m.

[0009] Step 2: Determine the parameter range of the ecological spur dike group:

[0010] 2.1: The ecological spur dikes are arranged in a staggered manner along the banks of the river. The height of the spur dikes is consistent with the normal water level of the river, which reduces the impact of flood season on river flow;

[0011] 2.2: The spur dike angle refers to the angle between the spur dike and the upstream river bank. The spur dike angle θ can be selected as positive (θ=90°) or upward (θ<90°). At this time, the backflow area behind the ecological spur dike is larger than that of the downward (θ>90°), providing a longer hydraulic retention time for pollutant retention and purification;

[0012] 2.3: The relative length of the spur dike refers to the ratio of the vertical projection L of the spur dike on the river width to the river width B. The relative length of the spur dike has a great influence on the area of ​​the backflow area behind the dam. The relative length of the ecological spur dike should be within the range of 1 / 3-3 / 5;

[0013] 2.4: According to engineering experience, the spur dam spacing D is generally 1.5-2.5 times the spur dam length;

[0014] 2.5: The number of spur dikes n is calculated by the length of the spur dike area S and the distance between the dikes D. The calculation formula is:

[0015]

[0016] Step 3: Simulate and calculate the specific values ​​of the angle of the ecological spur dike group, relative spur dike length, spur dike spacing, and number of spur dikes:

[0017] First, investigate the topographic conditions and water quality and quantity conditions of the receiving river, select parameter combinations within the given spur dike parameter range, determine the simulation boundary conditions and initial conditions, build the model and perform grid division;

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

[0019] Furthermore, preliminary investigations were conducted on the regional pipe network and underlying surface conditions to determine the complexity of the regional runoff generation and convergence process, and based on this, the calculation method for the regulation and storage volume V of the ecological spur dam group area was selected;

[0020] If the regional pipe network is simple and the underlying surface is relatively simple, the empirical formula method is directly used for calculation. The empirical formula method requires further investigation of the regional rainfall and the underlying surface distribution. The design rainfall H uses the rainfall intensity of the study area once every two years, and the comprehensive rainfall runoff index is The runoff index of a single underlying surface is calculated based on the proportion of each underlying surface. The runoff index of a single underlying surface is based on the Technical Guidelines for Sponge City Construction - Construction of Low-Impact Development Rainwater System (Trial)

[0021]

[0022] Where: V is the storage capacity, m 3 ; H is the design rainfall, mm; is the comprehensive rainfall runoff coefficient; F is the catchment area, hm 2 ;

[0023] If the regional pipe network is complex and the underlying surface types are diverse, the SWMM model is used for simulation and calculation. The SWMM model simulation requires the acquisition of the terrain slope, rainfall data, permeability coefficient, surface runoff process parameters, pipe network runoff process parameters, and surface pollutant accumulation and flushing process parameters of the study area. First, it is necessary to generalize the sub-catchment areas of the study area, divide the larger area into several smaller hydrological units that directly discharge surface rainfall runoff to a single discharge point, input the parameters into the SWMM model, and construct the SWMM model of the study area. On the basis of determining the sensitivity of the relevant parameters by the modified Morse classification screening method, the parameters with higher parameters are identified, calibrated using the measured water quality and quantity data, and the model parameters are determined. The SWMM model is used for simulation and analysis to obtain the rainwater outlet water volume and pollution load, and to determine the rainwater interception and storage capacity.

[0024] The normal river water level in step 2.1 refers to the elevation value of a certain location in a river or lake, obtained after long-term observation of the water level, at which 50% of the water levels in one or several years are equal to or exceed the water level.

[0025] Furthermore, the control equation of the hydrodynamic-water quality model constructed in step 3 is as follows:

[0026] (1) Hydrodynamic control equation

[0027]

[0028]

[0029] Formula (4) is the continuity equation of water flow, where x i are the Cartesian x, y, and z directions, and u irepresents the flow velocity in the corresponding direction; Formula (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. is the Reynolds stress term; due to The unknown is solved by using the turbulence model κ-ε model, whose control equations include:

[0030]

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

[0032]

[0033]

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

[0035] (2) Control equations of material migration and transformation process

[0036]

[0037] Where C is the concentration of pollutants, D i is the diffusion coefficient in the corresponding direction, S L is the pollution source term, K is the linear attenuation coefficient of the pollutant;

[0038] The suspended matter mainly considers the migration process, and its control equation is:

[0039]

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

[0041] According to the output of the model, the hydrodynamics and pollutant distribution of the ecological spur dike area were drawn, and the spur dike parameter combinations with the highest water flow stability p and pollutant removal rate q in the ecological spur dike area under different spur dike angles, relative dam lengths, dam spacings and spur dike numbers were compared.

[0042]

[0043] In the formula, v 入 、v 出 are the flow velocities at the inlet and outlet of the ecological spur dam, c 入 、c出 are the pollutant concentrations at the inlet and outlet of the ecological spur dam, respectively.

[0044] The ecological spur dike group for controlling pollution of rainfall runoff into a river is obtained by the above-mentioned method of laying out the ecological spur dike group for controlling pollution of rainfall runoff into a river.

[0045] Furthermore, it includes a plurality of ecological spur dikes staggered on both sides of the river, and the ecological spur dikes are located at the downstream side of the rainwater outlet of the river.

[0046] Furthermore, the ecological spur dam includes pinewood piles, bamboo strips, colored strips, filling soil, gravel, emergent plants planted on top and iron nails. The outermost part of the ecological spur dam is fixed with pinewood piles, which are driven into the ground in rows along the outer periphery of the spur dam. The depth of the pinewood piles driven into the ground is 1 / 2 of the height of the spur dam. The diameter of the pinewood piles used is about 5-10cm. The inner layer of the pinewood piles is reinforced with bamboo strips, which are also driven into the ground in rows. The depth of the pinewood piles driven into the ground is 1 / 3 of the height of the spur dam. The width of the bamboo strips used is about 4-10cm. 8cm, thickness greater than 0.8cm, the inner layer of bamboo pieces is isolated with colored strips to prevent soil loss inside the spur dam, the upper end of the colored strips is fixed on the bamboo pieces with iron nails, one iron nail is nailed every 3-4 bamboo pieces, the lower end of the colored strips is buried under the filling soil for fixation, the filling soil can be dried on site with bottom mud, and the moisture content is controlled at about 40-60%, the filling soil is compacted and filled into the spur dam, 2-3cm thick gravel is piled on top of the filling soil, and local emergent plants with landscape effects are planted on top of the filling soil.

[0047] The beneficial effects of the present invention are:

[0048] The present invention utilizes ecological spur dikes in situ to control pollution of rainfall runoff entering the river in urban rivers, which can not only buffer large amounts of rainfall runoff, but also promote rapid sedimentation of suspended matter in the rainfall runoff and retention of dissolved pollutants, thereby reducing the impact of rainfall runoff on the water environment of the receiving river.

[0049] The ecological spur dam of the present invention has a simple structure, and the materials used are environmentally friendly. It will not cause secondary pollution to the river water environment, and has certain landscape benefits. By using numerical model simulation calculation to obtain the layout mode of the ecological spur dam group, the pollution of rainfall runoff can be controlled more accurately and efficiently, reducing the waste caused by more spur dams and the risk of rainfall runoff polluting the river water environment due to fewer spur dams. The present invention uses the receiving river to carry out in-situ regulation and purification of rainfall runoff, which to a certain extent alleviates the problems of traditional regulation and storage facilities in urban built-up areas. The pollution of rainfall runoff is intercepted and controlled at the rainwater outlet, reducing the impact of pollutants carried by rainfall runoff on the water environment of the receiving river. At the same time, the spur dam group can adjust the hydrodynamic conditions and reduce the impact of large water volumes on the river water ecosystem. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of the plan layout of the ecological spur dam group.

[0051] Figure 2 It is a top view of the ecological spur dike of the present invention.

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

[0053] List of reference numerals: 1—pinewood stakes, 2—bamboo pieces, 3—colored strips of cloth, 4—filling soil, 5—gravel, 6—emergent plants, 7—iron nails. DETAILED DESCRIPTION

[0054] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0055] The ecological spur dike group used for pollution control of rainfall runoff entering the river includes several ecological spur dikes staggered on both sides of the river. The ecological spur dike is located on the downstream side of the rainwater outlet of the river. The ecological spur dike includes pine wood piles, bamboo pieces, colored strips, filling soil, gravel, emergent plants planted on top, and iron nails. The outermost part of the ecological spur dike is fixed with pine wood piles. The pine wood piles are driven into the ground in rows along the outer periphery of the spur dike. The depth of the pine wood piles driven into the ground is 1 / 2 of the height of the spur dike. The diameter of the pine wood piles used is about 5-10cm. The inner layer of the pine wood piles is reinforced with bamboo pieces. The bamboo pieces are also driven into the ground in rows. The depth of the underground driving is 1 / 3 of the height of the spur dike. The width of the bamboo pieces used is about 4-8cm. The thickness is greater than 0.8cm. The inner layer of the bamboo strips is isolated with colored strips to prevent soil loss inside the spur dam. The upper end of the colored strips is fixed to the bamboo strips with iron nails, and an iron nail is nailed every 3-4 bamboo strips. The lower end of the colored strips is buried under the filling soil for fixation. The filling soil can be dried on site with bottom mud to control the moisture content at about 40-60%. The filling soil is compacted and filled into the spur dam. 2-3cm thick gravel is piled on top of the filling soil, and local emergent plants with landscape effects are planted on top of the filling soil.

[0056] Firstly, the specific parameters of the ecological spur dam area are determined according to a method for laying out ecological spur dams for controlling pollution of rainfall runoff entering rivers.

[0057] Combination Figure 1 The method for laying out the ecological spur dike group for controlling the pollution of rainfall runoff entering the river is specifically as follows:

[0058] Step 1: According to the rainfall and underlying surface conditions in the survey area, the storage capacity of the ecological spur dam area is obtained through empirical formulas or SWMM model simulations. The length of the ecological spur dam area is preliminarily calculated based on the storage capacity and river depth. The calculation formula is as follows:

[0059]

[0060]

[0061] Where: V is the designed storage capacity, m 3 ; H is the design rainfall, mm; is the comprehensive rainfall runoff coefficient; F is the catchment area, hm 2 ; S is the length of the ecological spur dike area, m; h is the depth of the receiving river, m; B is the width of the river channel, m.

[0062] Step 2: Determine the range of ecological spur dike parameters. Figure 1 As shown in the figure, the ecological spur dikes are arranged alternately along the two banks of the river. The height of the spur dike is consistent with the normal water level of the river, which reduces the impact of the flood season on the river flow. The angle of spur θ is generally selected as positive spur (θ=90°) or upward spur (θ<90°). At this time, the area of ​​the backflow area behind the ecological spur dike is larger than that of the downward spur (θ>90°), providing more hydraulic retention time for pollutant retention and purification. The relative length of the spur dike has a greater impact on the area of ​​the backflow area behind the dam. The relative length of the ecological spur dike is in the range of 1 / 3-3 / 5. According to engineering experience, the spacing between spur dikes is generally 1.5-2.5 times the length of the spur dike.

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

[0064] Table 1 Spur dike structural parameters and layout methods

[0065]

[0066] By performing orthogonal combination of parameters, a total of 27 parameter combinations can be obtained. The number of spur dikes is calculated by the length of the spur dike area and the distance between the dikes. The calculation formula is:

[0067]

[0068] Determine the spur dike parameter combination, build a hydrodynamic-water quality model for simulation calculation based on the receiving river terrain conditions, and obtain the optimal ecological spur dike layout parameter combination. The control equation of the constructed hydrodynamic-water quality model is as follows:

[0069] (1) Hydrodynamic control equation

[0070]

[0071] Formula 4 is the continuity equation of water flow, where x i are the Cartesian x, y, and z directions, and u iIndicates the flow velocity in the corresponding direction. Formula 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. is the Reynolds stress term. The unknown is solved by using the turbulence model κ-ε model, whose control equations include:

[0072]

[0073] In the formula, κ is the turbulent kinetic energy, ε is the energy dissipation rate, and G is the turbulent kinetic energy generation term. The calculation of G is:

[0074]

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

[0076] (2) Control equations of material migration and transformation process

[0077]

[0078] Where C is the concentration of pollutants, D i is the diffusion coefficient in the corresponding direction, S L is the pollution source term, and K is the linear attenuation coefficient of the pollutant.

[0079] The suspended matter is mainly a migration process, and its control equation is:

[0080]

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

[0082] According to the output of the model, the hydrodynamics and pollutant distribution of the ecological spur dike area were drawn, and the spur dike parameter combinations with the highest water flow stability p and pollutant removal rate q in the ecological spur dike area under different spur dike angles, relative dam lengths, dam spacings and spur dike numbers were compared.

[0083]

[0084] In the formula, v 入 、v 出 are the flow velocities at the inlet and outlet of the ecological spur dam, c 入 、c 出 are the pollutant concentrations at the inlet and outlet of the ecological spur dam, respectively.

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

[0086] After determining the specific parameters of the spur dike, the construction of a single spur dike can be carried out. Figure 2-3 As shown, the structure of an ecological spur dam for controlling pollution of rainfall runoff entering a river includes pinewood piles 1, bamboo pieces 2, colored strips 3, filling soil 4, gravel 5, emergent plants 6 planted on top, and iron nails 7. The outermost part of the ecological spur dam is fixed with pinewood piles 1, which are driven into the ground in rows along the outer periphery of the spur dam, and the depth of the pinewood piles 1 driven into the ground is 1 / 2 of the height of the spur dam. The diameter of the pinewood piles 1 used is about 5 cm. The inner layer of the pinewood piles 1 is reinforced with bamboo pieces 2, which are also driven into the ground in rows, and the depth of the pinewood piles 1 driven into the ground is 1 / 3 of the height of the spur dam. The width of the bamboo pieces 2 used is about 5 cm, and the thickness is greater than 0.8 cm. The inner layer of the bamboo pieces 2 is isolated with colored strips 3 to prevent soil loss inside the spur dam. The upper end of the colored strips 3 is fixed to the bamboo pieces 2 with iron nails 7, and one iron nail is nailed every 3-4 bamboo pieces. The lower end of the colored strips 3 is buried under the filling soil 4 for fixing. The filling soil 4 can be dried on site using bottom mud, and the moisture content is controlled to be about 40-60%. The filling soil 4 is compacted and filled into the groin, and 2-3 cm thick gravel 5 is piled on the filling soil 4. Local emergent plants 6 with landscape effects, such as canna, Lythrum salicaria, etc., are planted on the filling soil 4.

[0087] An embodiment of a specific application of this patent is given below

[0088] The ecological spur dike group was constructed in the landscape wetland of Yixing Urban Wastewater Resource Concept Plant for testing. The landscape wetland is low in terrain, and nearly half of the rainwater in the plant area is collected here. The total area of ​​the concept plant is about 2.5hm 2 The underlying surface is mainly roofs, roads and green spaces. The specific proportions of the underlying surface are shown in Table 2. Since the underlying surface conditions in the conceptual plant area are relatively simple and the area is small, the empirical formula method is used to calculate the storage volume V.

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

[0090]

[0091] The weighted calculation of the above table shows that the comprehensive rainfall runoff coefficient of the area is 0.31. The design rainfall is the rainfall intensity of Yixing City once in two years. The rainfall in the first 30 minutes is taken as the design rainfall. According to formula 1, the storage capacity V is 50m 3 The average depth of the wetland is 0.4m, the average width is 3.5m, and the length of the ecological spur dike area is 35.8m according to Formula 2.

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

[0093] Table 3 Ecological spur dike parameter combination table

[0094]

[0095]

[0096] According to the output of the model, the hydrodynamics and pollutant distribution of the ecological spur dike area were drawn, and the spur dike parameter combinations with the highest water flow stability p and pollutant removal rate q in the ecological spur dike area were compared under different spur dike angles, relative dam lengths, dam spacings, and spur dike numbers. Finally, the comparison showed that when the spur dike angle was 60°, the relative dam length was 3 / 5, the dam spacing was 4.20m, and the number of dams was 8, the water flow stability p, suspended solids, and NH4 + , TN, TP and COD removal rates are optimal.

[0097] Table 4 Ecological spur dam effect table

[0098]

[0099] With the above-mentioned ideal embodiments of the present invention as inspiration, through the above-mentioned description content, relevant personnel can make various changes and modifications without departing from the scope of the technical idea of ​​the present invention.

Claims

1. A method for laying out an ecological spur dike group for controlling pollution of rainfall runoff entering a river, characterized in that: The steps include: Step 1: Select the study area, and obtain the storage capacity V of the ecological spur dam area through empirical formula or SWMM model simulation. Preliminary calculation of the length S of the ecological spur dam area is based on the storage capacity and the river depth and width. The calculation formula is as follows: Where, S is the length of the ecological spur dike area, m; h is the receiving river depth, m; B is the river width, m; Step 2: Determine the parameter range of the ecological spur dike group: 2.1: The ecological spur dikes are arranged alternately along the banks of the river, and the height of the spur dikes is consistent with the normal water level of the river; 2.2: The spur dike angle θ can be selected as positive (θ=90°) or upward (θ<90°); 2.3: The relative length of the spur dike refers to the ratio of the vertical projection L of the spur dike on the river width to the river width B. The relative length of the spur dike has a great influence on the area of ​​the backflow area behind the dam. The relative length of the ecological spur dike should be within the range of 1 / 3-3 / 5; 2.4: According to engineering experience, the distance D between ecological spur dikes is 1.5-2.5 times the length of the spur dike; 2.5: The number of spur dikes n is calculated by the length S of the ecological spur dike area and the distance D between spur dikes. The calculation formula is: Step 3: Simulate and calculate the specific values ​​of the angle of the ecological spur dike group, relative spur dike length, spur dike spacing, and number of spur dikes: First, investigate the topographic conditions and water quality and quantity conditions of the receiving river, select parameter combinations within the given spur dike parameter range, determine the simulation boundary conditions and initial conditions, build the model and perform grid division; The simulation calculation uses fluid mechanics theory to construct a hydrodynamic-water quality numerical model. Grids with different parameter combinations are imported into the model for calculation to obtain the hydrodynamics and pollutant migration transformation in the ecological spur dam area. By comparing the stability of the water flow and the removal of pollutants, the parameter combination with the best water flow conditions, suspended solids sedimentation and pollutant retention effects is selected.

2. The method for laying out an ecological spur dike group for controlling pollution of rainfall runoff entering a river according to claim 1, characterized in that: Preliminary investigation of the regional pipe network and underlying surface conditions, determination of the complexity of the regional runoff generation and convergence process, and selection of the calculation method for the regulation and storage volume V of the ecological spur dam group area; If the regional pipe network is simple and the underlying surface is relatively simple, the empirical formula method is directly used for calculation. The empirical formula method requires further investigation of the regional rainfall and the underlying surface distribution. The design rainfall H uses the rainfall intensity of the study area once every two years, and the comprehensive rainfall runoff index is Calculate based on the proportion of each underlying surface: Where V is the storage capacity, m 3 ; H is the design rainfall, mm; is the comprehensive rainfall runoff coefficient; F is the catchment area, hm 2 . If the regional pipe network is complex and the underlying surface types are diverse, the SWMM model is used for simulation and calculation. The SWMM model simulation requires the acquisition of the terrain slope, rainfall data, permeability coefficient, surface runoff process parameters, pipe network runoff process parameters, and surface pollutant accumulation and flushing process parameters of the study area. First, it is necessary to generalize the sub-catchment areas of the study area, divide the larger area into several smaller hydrological units that directly discharge surface rainfall runoff to a single discharge point, input the parameters into the SWMM model, and construct the SWMM model of the study area. On the basis of determining the sensitivity of the relevant parameters by the modified Morse classification screening method, the parameters with higher parameters are identified, calibrated using the measured water quality and quantity data, and the model parameters are determined. The SWMM model is used for simulation and analysis to obtain the rainwater outlet water volume and pollution load, and to determine the rainwater interception and storage capacity.

3. The method for laying out an ecological spur dike group for controlling pollution of rainfall runoff entering a river according to claim 1, characterized in that: The control equation of the hydrodynamic-water quality model constructed in step 3 is as follows: (1) Hydrodynamic control equation Formula (4) is the continuity equation of water flow, where x i are the Cartesian x, y, and z directions, and u i represents the flow velocity in the corresponding direction; Formula (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. is the Reynolds stress term; due to The unknown is solved by using the turbulence model κ-ε model, whose control equations include: In the formula, κ is the turbulent kinetic energy, ε is the energy dissipation rate, and G is the turbulent kinetic energy generation term; G is calculated as: In the formula, C μ , C1, C2, σ κ and σ ε are all constants; (2) Control equation of material migration and transformation process Where C is the concentration of pollutants, D i is the diffusion coefficient in the corresponding direction, S L is the pollution source term, K is the linear attenuation coefficient of the pollutant; The suspended matter mainly considers the migration process, and its control equation is: In the formula, S, S * is the suspended matter concentration in the water flow and the saturated suspended matter concentration in the water flow; ε s is the turbulent diffusion coefficient; ω is the suspended matter settling velocity; α is the suspended matter recovery saturation coefficient.

4. The method for laying out an ecological spur dike group for controlling pollution of rainfall runoff entering a river according to claim 1, characterized in that: According to the output of the model, the hydrodynamics and pollutant distribution in the ecological spur dike area were drawn, and the spur dike parameter combinations with the highest water flow stability p and pollutant removal rate q in the ecological spur dike area under different spur dike angles, relative dam lengths, dam spacings and spur dike numbers were compared: In the formula, v 入 、v 出 are the flow velocities at the inlet and outlet of the ecological spur dam, c 入 、c 出 are the pollutant concentrations at the inlet and outlet of the ecological spur dam, respectively.

5. An ecological spur dike group for controlling pollution of rainfall runoff into a river obtained by the method for laying out an ecological spur dike group for controlling pollution of rainfall runoff into a river as described in any one of claims 1 to 4.

6. The ecological spur dike group for controlling pollution of rainfall runoff entering a river according to claim 5, characterized in that: It includes several ecological spur dikes staggered on both sides of the river, and the ecological spur dike is located on the downstream side of the rainwater outlet of the river.

7. The ecological spur dike group for controlling pollution of rainfall runoff entering a river according to claim 5, characterized in that: The ecological spur dam includes pinewood piles, bamboo pieces, colored strips, filling soil, gravel, emergent plants planted on top and iron nails. The outermost part of the ecological spur dam is fixed with pinewood piles, which are driven into the ground in rows along the outer periphery of the spur dam. The depth of the pinewood piles driven into the ground is 1 / 2 of the height of the spur dam. The diameter of the pinewood piles used is about 5-10cm. The inner layer of the pinewood piles is reinforced with bamboo pieces, which are also driven into the ground in rows. The depth of the pinewood piles driven into the ground is 1 / 3 of the height of the spur dam. The width of the bamboo pieces used is about 4-8cm The thickness is greater than 0.8cm. The inner layer of the bamboo strips is isolated with colored strips to prevent soil loss inside the spur dam. The upper end of the colored strips is fixed to the bamboo strips with iron nails, and an iron nail is nailed every 3-4 bamboo strips. The lower end of the colored strips is buried under the filling soil for fixation. The filling soil can be dried on site with bottom mud to control the moisture content at about 40-60%. The filling soil is compacted and filled into the spur dam. 2-3cm thick gravel is piled on top of the filling soil, and local emergent plants with landscape effects are planted on top of the filling soil.

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