Basin pollution load accounting system and source-sink response simulation method thereof

Abstract

The invention relates to the technical field of environmental protection, in particular to a drainage basin pollution load accounting system and a source-sink response simulation method thereof.The drainage basin pollution load accounting system comprises a drainage basin data module, a non-point source pollution module, a point source emission module and a hydrodynamic simulation module, and the drainage basin data module inputs information and simulates hydraulic and water quality scenes; the non-point source pollution module simulates non-point source pollution amounts of different land utilization types; and the point source emission module calculates the point source pollution emission. The hydrodynamic simulation module performs simulation in combination with drainage basin data and meteorological boundary conditions; the dynamic TMDL allocation module realizes dynamic allocation of the total amount of pollutants based on a source-sink response result, and the accounting precision is improved through coupling of an SWAT model and an EFDC model; according to the system, an administrative village is adopted as a minimum calculation unit, and an APCS-MLR model is combined to realize accurate quantification of non-point source pollution; according to the system, land and water systems are effectively integrated, and the accuracy and efficiency of drainage basin pollution load accounting and management are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection, and particularly relates to a basin pollution load accounting system and a source-sink response simulation method thereof, which are used for accurately accounting the basin pollution load and realizing the response simulation between the pollution source and the sink. Background Art

[0002] In the process of basin water environment management, accurately accounting the pollution load and simulating the migration and transformation process of pollutants in the basin are the basis for realizing scientific control.

[0003] Traditional basin pollution load accounting methods usually use a single model for calculation. For example, the SWAT model is applied to calculate the non-point source pollution load, or the EFDC model is used to simulate the migration and transformation of pollutants in water bodies. However, a single model is difficult to comprehensively reflect the complex hydrological processes and pollutant migration and transformation processes in the basin, resulting in large errors in the accounting results. At the same time, the existing technology lacks an accurate simulation of the response relationship between the pollution source and the receptor, and it is difficult to provide a scientific basis for basin pollution control.

[0004] In addition, traditional total amount control methods usually adopt a static allocation method, which cannot adapt to the dynamic changes of hydrological conditions and pollutant emissions in the basin, resulting in limitations in the scientific nature and effectiveness of total amount control. Therefore, there is an urgent need to develop a system that can accurately account for the basin pollution load and realize the source-sink response simulation to provide scientific support for basin water environment management. Summary of the Invention

[0005] The purpose of the present invention is to provide a basin pollution load accounting system and a source-sink response simulation method thereof. By constructing a coupling framework of the SWAT model and the EFDC model, integrating the non-point source pollution coefficient library and the point source emission inventory, and realizing the dynamic allocation of the TMDL total amount, the basin pollution load can be accurately accounted and the response simulation between the pollution source and the sink can be realized, providing scientific support for basin water environment management.

[0006] The present invention provides a basin pollution load accounting system, including:

[0007] A basin data module, which is used for inputting basin information and simulating hydraulic and water quality scenarios through a calculation model;

[0008] A non-point source pollution module, which is used for simulating the non-point source pollution amount of different land use types under the change of basin meteorology;

[0009] A point source emission module, which is used for accounting the point source pollution emissions in the basin;

[0010] A hydrodynamic simulation module, which is connected to the basin data module, the non-point source pollution module and the point source emission module, and is used for carrying out hydrodynamic and water quality simulation by combining the basin data and the boundary conditions input by meteorological driving;

[0011] A dynamic TMDL allocation module, connected to the hydrodynamic simulation module, is used to realize the dynamic allocation of the total amount of pollutants in the basin based on the source-sink response simulation results.

[0012] Preferably, the basin data module includes a topographic file, a soil database, a meteorological database, and reservoir data for input, the basin information includes basin runoff, basin land use types, and basin runoff model parameters, and the calculation model includes a coupling framework of the SWAT model and the EFDC model.

[0013] Preferably, the non-point source pollution module includes:

[0014] The minimum administrative village calculation unit is used to extract the area, administrative division boundary, and land use type data of each administrative village in the basin;

[0015] The APCS-MLR non-point source pollution coefficient model, connected to the minimum administrative village calculation unit, is used to construct a non-point source pollution coefficient calculation model for the basin based on the land use type data;

[0016] The non-point source load into the river calculation unit, connected to the APCS-MLR non-point source pollution coefficient model, is used to calculate the contribution rate of non-point source pollutants entering the river in the basin.

[0017] Preferably, the point source emission module includes:

[0018] The point source type identification unit is used to identify pollution sources in sewage outfalls, lakes, and the inflow of point source pollutants from agricultural activities, cities, and industrial areas in the riparian zone and non-riparian zone;

[0019] The point source total amount calculation unit, connected to the point source type identification unit, is used to calculate the total amount of the load of point source pollutants entering the river according to the point source type.

[0020] Preferably, the hydrodynamic simulation module includes:

[0021] The SWAT model processing unit is used to calculate the non-point source pollution load of pollutants such as nitrogen and phosphorus caused by agricultural chemical management flowing into each hydrological response unit in the basin;

[0022] The EFDC model processing unit, connected to the SWAT model processing unit, is used to read the pollution load allocation ratio, outflow, riverbed sediment component data, and initial concentration field data for river network hydrodynamic calculation.

[0023] Preferably, the dynamic TMDL allocation module includes:

[0024] A load distribution ratio calculation unit, which is used to calculate the total amount of water taken at the water intake according to the calculated non-point source load distribution percentage, point source emission load distribution ratio, and distribution coefficients of various water quality indicators.

[0025] An actual emission total calculation unit, connected to the load distribution ratio calculation unit, which is used to calculate the actual total emission of water quality indicators within the map unit.

[0026] An in-river load optimization unit, connected to the actual emission total calculation unit, which is used to summarize the actual total emission of water quality indicators and the emission distribution ratio, calculate the in-river load of the water quality indicator in the basin, and optimize the contribution ratio of all non-point sources within the basin.

[0027] Preferably, it further includes a source-sink response simulation module, which is used to construct data sequences of input flow rates for each branch where pollutants flow into the main stream and for confluence between intervals, and taking the river channel control section as a node, allocate the tributary and confluence flow rates to the corresponding main stream reaches of each river channel control section and the corresponding reaches of the estuaries where they flow into the main stream.

[0028] Preferably, the source-sink response simulation module is further used for:

[0029] Constructing runoff and water quality monitoring data of each river channel control section with the distributed SWAT model of the basin as the data platform and the monitored runoff mode as the control period.

[0030] Constructing a pollution reduction scenario with the superposition of pollutant output and changes in water use types and a pollution control scenario with the superposition of changes in land use types.

[0031] Preferably, the source-sink response simulation module is further used for:

[0032] Based on the hydrodynamic model of EFDC, through the pollutant output of each land use type on each section control surface, simulating the pollution distribution state of the reaches upstream and downstream of each section control surface.

[0033] Allocating the pollutant output to the main stream river network and tributary estuaries on each section control surface to form the simulated pollutant amount of the section.

[0034] Calculating the difference between the sum of the cumulative input amounts of pollutants at the river channel control section and the sum of the simulated pollutant amounts of the section corresponding to each section control surface to form a pollution net load balance equation.

[0035] The source-sink response simulation method for basin pollution load accounting based on the basin pollution load accounting system of the present invention includes the following steps:

[0036] Constructing a coupling framework of the SWAT model and the EFDC model, including:

[0037] Run the SWAT model using topographic files, soil databases, meteorological databases, and reservoir data, and input the land use and meteorological data of the basin;

[0038] Calculate the non-point source pollution load of pollutants such as nitrogen and phosphorus caused by agricultural chemical management flowing into each hydrological response unit of the basin;

[0039] Read the total output of non-point source pollutants on the hydrological response units in each sub-basin of the SWAT model and the allocation ratio of non-point source pollutants into the river, and calculate the ratio of non-point source pollution load into the river;

[0040] Take the non-point source pollutant load allocation ratio and the outflow of each hydrological response unit as the input of the EFDC model;

[0041] The EFDC model reads the pollution load allocation ratio, outflow, riverbed sediment component data, and initial concentration field data for river network hydrodynamic calculation;

[0042] Integrate the non-point source pollution coefficient library and point source emission inventory to achieve dynamic total allocation of TMDL, including:

[0043] According to the calculated non-point source load allocation percentage, point source emission load allocation ratio, and allocation coefficient of each water quality index, calculate the total water intake of the water intake point;

[0044] According to the calculated total water intake, calculate the actual total emission of this water quality index within the map unit;

[0045] Summarize the actual total emission of water quality index and emission allocation ratio, calculate the river inflow load of this water quality index in the basin, optimize the contribution ratio of all non-point sources in the basin, and achieve dynamic total allocation of basin pollutants.

[0046] The beneficial effects of the present invention are as follows:

[0047] 1. By constructing a coupling framework of the SWAT model and the EFDC model, efficient integration of the land and water systems is achieved, and the accuracy of basin pollution load accounting is improved;

[0048] 2. Adopting the method with administrative villages as the smallest calculation unit and combining with the APCS-MLR non-point source pollution coefficient model, accurate quantification of non-point source pollution is achieved;

[0049] 3. Through the dynamic TMDL allocation mechanism, scientific dynamic allocation of basin pollutant total amounts is achieved, overcoming the limitations of traditional static allocation methods;

[0050] 4. A complete source-sink response simulation method is established, realizing the whole-process simulation of pollutants from the source to the end point, providing a scientific basis for basin water environment management. Description of the Drawings

[0051] Figure 1 It is a schematic structural diagram of the basin pollution load accounting system of the present invention;

[0052] Figure 2 It is a schematic structural diagram of the non-point source pollution module of the present invention;

[0053] Figure 3 It is a schematic structural diagram of the point source emission module of the present invention;

[0054] Figure 4 It is a schematic structural diagram of the hydrodynamic simulation module of the present invention;

[0055] Figure 5 It is a schematic structural diagram of the dynamic TMDL allocation module of the present invention;

[0056] Figure 6 It is a flow chart of the source-sink response simulation method for the basin pollution load accounting of the present invention. Detailed implementation manners

[0057] Please refer to the appendix Figure 1-6 , the present invention provides a basin pollution load accounting system, including:

[0058] A basin data module 1, configured to input basin information and simulate hydraulic and water quality scenarios through a calculation model;

[0059] A non-point source pollution module 2, configured to simulate the non-point source pollution amounts of different land use types under the meteorological changes in the basin;

[0060] A point source emission module 3, configured to account for the point source pollution emissions in the basin;

[0061] A hydrodynamic simulation module 4, connected to the basin data module 1, the non-point source pollution module 2 and the point source emission module 3, and configured to perform hydrodynamic and water quality simulations in combination with the boundary conditions input by the basin data and meteorological driving;

[0062] A dynamic TMDL allocation module 5, connected to the hydrodynamic simulation module 4, and configured to realize the dynamic allocation of the total amount of basin pollutants based on the source-sink response simulation results.

[0063] In an embodiment of the present invention, the basin data module 1 includes a terrain file 11 for input, a soil database 12, a meteorological database 13 and reservoir data 14, the basin information includes basin runoff, basin land use type and basin runoff model parameters, and the calculation model includes a coupling framework of the SWAT model and the EFDC model.

[0064] Preferably, the non-point source pollution module 2 includes:

[0065] The smallest administrative village calculation unit 21 is used to extract data on the area of each administrative village, administrative division boundaries, and land use types within the basin;

[0066] The APCS-MLR non-point source pollution coefficient model 22 is connected to the smallest administrative village calculation unit 21 and is used to construct a non-point source pollution coefficient calculation model for the basin based on the land use type data;

[0067] The non-point source river input load calculation unit 23 is connected to the APCS-MLR non-point source pollution coefficient model 22 and is used to calculate the contribution rate of non-point source pollutants entering the river in the basin.

[0068] In another embodiment of the present invention, the point source emission module 3 includes:

[0069] The point source type identification unit 31 is used to identify pollution sources in sewage outfalls, lakes, and the inflow of point source pollutants from agricultural activities, cities, and industrial areas in the riparian zone and non-riparian zone;

[0070] The point source total amount calculation unit 32 is connected to the point source type identification unit 31 and is used to calculate the total amount of point source pollutants entering the river according to the point source type.

[0071] Preferably, the hydrodynamic simulation module 4 includes:

[0072] The SWAT model processing unit 41 is used to calculate the non-point source pollution load of pollutants such as nitrogen and phosphorus caused by agricultural chemical management flowing into each hydrological response unit in the basin;

[0073] The EFDC model processing unit 42 is connected to the SWAT model processing unit 41 and is used to read the pollution load distribution ratio, outflow, riverbed sediment component data, and initial concentration field data for river network hydrodynamic calculation.

[0074] In a preferred embodiment of the present invention, the dynamic TMDL allocation module 5 includes:

[0075] The load allocation ratio calculation unit 51 is used to calculate the total amount of water taken at the water intake according to the calculated non-point source load allocation percentage, point source emission load allocation ratio, and the allocation coefficient of each water quality index;

[0076] The actual emission total amount calculation unit 52 is connected to the load allocation ratio calculation unit 51 and is used to calculate the actual total emission amount of water quality indicators within the map unit;

[0077] The river input load optimization unit 53 is connected to the actual emission total amount calculation unit 52 and is used to summarize the actual total emission amount of water quality indicators and the emission allocation ratio, calculate the river input load of this water quality indicator in the basin, and optimize the contribution ratio of all non-point sources in the basin.

[0078] In yet another embodiment of the present invention, the system further includes a source-sink response simulation module 6, which is used to construct input flow data sequences of various branches where pollutants flow into the main stream and lateral inflows, and taking the river control section as a node, distribute the tributary and lateral inflow discharges to the main stream reaches corresponding to each river control section and the reaches corresponding to the estuaries where they flow into the main stream.

[0079] Preferably, the source-sink response simulation module 6 is further used for:

[0080] Constructing runoff and water quality monitoring data of each river control section with the distributed SWAT model of the basin as the data platform and the monitored runoff mode as the control period;

[0081] Constructing a pollution reduction scenario with the superposition of pollutant output and changes in water consumption types and a pollution control scenario with the superposition of changes in land use types.

[0082] Furthermore, the source-sink response simulation module 6 is further used for:

[0083] Based on the hydrodynamic model of EFDC, simulating the pollution distribution status of the reaches upstream and downstream of each section control surface through the pollutant output of each land use type on each section control surface;

[0084] Distributing the pollutant output to the main stream river network and tributary estuaries on each section control surface to form the simulated pollutant quantity of the section;

[0085] Calculating the difference between the sum of the cumulative input amounts of pollutants at the river control section and the sum of the simulated pollutant quantities of the section corresponding to each section control surface to form a pollution net load balance equation.

[0086] The present invention also provides a source-sink response simulation method for basin pollution load accounting based on the above-mentioned basin pollution load accounting system, including the following steps:

[0087] Constructing a coupling framework of the SWAT model and the EFDC model, including:

[0088] Running the SWAT model with topographic files, soil databases, meteorological databases, and reservoir data, and inputting land use and meteorological data of the basin;

[0089] Calculating the non-point source pollution load of pollutants such as nitrogen and phosphorus flowing into each hydrological response unit of the basin due to agricultural chemical management;

[0090] Reading the total output of non-point source pollutants in each sub-basin of the SWAT model on the hydrological response unit and the allocation ratio of non-point source pollutant river inflow loads, and calculating the non-point source pollution load river inflow ratio;

[0091] The non-point source pollutant load allocation ratio and the outflow of each hydrological response unit are used as the inputs of the EFDC model;

[0092] The EFDC model reads the pollution load allocation ratio, the outflow, as well as the riverbed sediment component data and the initial concentration field data to perform river network hydrodynamic calculations;

[0093] Integrate the non-point source pollution coefficient library and the point source emission inventory to achieve dynamic allocation of the total TMDL amount, including:

[0094] According to the calculated non-point source load allocation percentage, the point source emission load allocation ratio, and the allocation coefficients of each water quality index, calculate the total amount of water intake at the water intake point;

[0095] According to the calculated total amount of water intake, calculate the actual total emission amount of this water quality index within the map unit;

[0096] Summarize the actual total emission amount and the emission allocation ratio of the water quality index, calculate the river inflow load of this water quality index in the basin, optimize the contribution ratio of all non-point sources within the basin, and achieve dynamic allocation of the total amount of pollutants in the basin.

[0097] The following will describe the embodiments of the present invention in detail with reference to the accompanying drawings, but the protection scope of the present invention is not limited thereto.

[0098] As Figure 1 shown, the present invention provides a basin pollution load accounting system, including a basin data module 1, a non-point source pollution module 2, a point source emission module 3, a hydrodynamic simulation module 4, and a dynamic TMDL allocation module 5.

[0099] The basin data module 1 is used to input basin information and simulate hydraulic and water quality scenarios through a calculation model. Specifically, as Figure 1 shown, the basin data module 1 includes a topographic file 11 for input, a soil database 12, a meteorological database 13, and reservoir data 14. The basin information includes basin runoff, basin land use types, and basin runoff model parameters, and the calculation model includes the coupling framework of the SWAT model and the EFDC model.

[0100] The SWAT model (Soil and Water Assessment Tool) is a distributed basin hydrological model that can simulate the hydrological cycle process within the basin and the generation, migration, and transformation process of non-point source pollutants. The EFDC model (Environmental Fluid Dynamics Code) is a three-dimensional hydrodynamic model that can simulate the migration and transformation process of pollutants in water bodies. The present invention innovatively constructs the coupling framework of the SWAT model and the EFDC model, realizes the efficient integration of the land and water systems, and improves the accuracy of basin pollution load accounting.

[0101] In the present invention, the terrain file 11 generally includes digital elevation model (DEM) data with a resolution of generally 30m×30m or higher, which is used to describe the terrain features of the basin. The soil database 12 includes information such as soil types and soil physical and chemical properties, which is used to describe the soil characteristics of the basin. The meteorological database 13 includes time series data of meteorological elements such as rainfall, temperature, wind speed, humidity, and solar radiation, usually on a daily basis. The reservoir data 14 includes information such as the location, volume, and operation rules of the reservoir, which is used to describe the characteristics of the reservoir in the basin and its impact on the hydrological process.

[0102] The non-point source pollution module 2 is used to simulate the non-point source pollution amounts of different land use types under the meteorological changes in the basin. As Figure 2 shown, the non-point source pollution module 2 includes the minimum administrative village calculation unit 21, the APCS-MLR non-point source pollution coefficient model 22, and the non-point source load into the river calculation unit 23.

[0103] The minimum administrative village calculation unit 21 is used to extract the area, administrative division boundary, and land use type data of each administrative village in the basin. Compared with traditional grid or sub-basin units, the administrative village unit better meets the actual management needs, improves the practicality of the model results, reduces the calculation complexity, and improves the operation efficiency. The statistical data at the administrative village level is easier to obtain and update, improving the application conditions of the model.

[0104] The APCS-MLR non-point source pollution coefficient model 22 is connected to the minimum administrative village calculation unit 21 and is used to construct a non-point source pollution coefficient calculation model for the basin based on the land use type data. The APCS-MLR (absolute principal component score - multiple linear regression) model is a statistical method that can effectively identify and quantify the contribution rates of various pollution sources. The present invention innovatively applies the APCS-MLR model to the calculation of non-point source pollution coefficients, realizing the precise quantification of non-point source pollution.

[0105] Specifically, the calculation process of the APCS-MLR non-point source pollution coefficient model 22 is as follows:

[0106] First, perform principal component analysis on the land use type data of each administrative village to extract the main influencing factors:

[0107]

[0108] Among them, PC i represents the i-th principal component, a ij represents the load of the j-th original variable on the i-th principal component, and X j represents the j-th original variable (proportion of land use type area).

[0109] Then, construct a multiple linear regression model to calculate the contribution rates of various land use types to non-point source pollution:

[0110]

[0111] Among them, C represents the non-point source pollution load, b0 is the constant term, b i represents the regression coefficient of the i-th principal component, PC i represents the i-th principal component.

[0112] The non-point source river input load calculation unit 23 is connected to the APCS-MLR non-point source pollution coefficient model 22 and is used to calculate the contribution rate of non-point source pollutants entering the river in the basin. The calculation method of the non-point source river input load calculation unit 23 is as follows:

[0113]

[0114] Among them, D represents the basin area (km 2 ), M represents the non-point source river input load (t), represents the sum of the area ratios of each land use type in each administrative village in the basin, B i represents the area ratio of each land use type in each administrative village.

[0115] The calculation method of the contribution rate of non-point source pollutants entering the river in the basin is as follows:

[0116]

[0117] Among them, C represents the percentage of the non-point source river input load in the river load, C sum represents the total load of total nitrogen and total phosphorus of non-point source entering the river in the basin, C total represents the total load of total nitrogen and total phosphorus in the river.

[0118] The point source emission module 3 is used to calculate the point source pollution emissions in the basin. As Figure 3 shown, the point source emission module 3 includes a point source type identification unit 31 and a point source total amount calculation unit 32.

[0119] The point source type identification unit 31 is used to identify the pollution sources in the sewage outfalls, lakes, and the inflows of point source pollutants from agricultural activities, cities, and industrial areas in the riparian zone and non-riparian zone. The point source type identification unit 31 can obtain point source information through remote sensing images, geographic information system (GIS) data, and field surveys, and classify it into different types of point source pollution sources.

[0120] The point source total amount calculation unit 32 is connected to the point source type identification unit 31 and is used to calculate the total amount of point source pollutants entering the river according to the point source type. The point source total amount calculation unit 32 uses the following model for calculation:

[0121] Y = ∑ S (YxS ×Q xS ) Among them, x is the point source type, such as agricultural point source, urban point source, industrial point source, etc.; Y is the total amount of point sources; S is the hydrological response unit where the point sources flow into the river network; xS is the point source type in a certain hydrological response unit S in the river network; Y xS is the total load of xS point sources entering the river in the hydrological response unit S; Q xS is the allocation ratio of xS point sources entering the river in the hydrological response unit S.

[0122] The hydrodynamic simulation module 4 is connected to the basin data module 1, the non-point source pollution module 2, and the point source emission module 3, and is used to perform hydrodynamic water quality simulation by combining the basin data and the boundary conditions of meteorological driving input. As Figure 4 shown, the hydrodynamic simulation module 4 includes a SWAT model processing unit 41 and an EFDC model processing unit 42.

[0123] The SWAT model processing unit 41 is used to calculate the non-point source pollution load of pollutants such as nitrogen and phosphorus caused by agricultural chemical management flowing into each hydrological response unit of the basin. Specifically, the SWAT model processing unit 41 runs the SWAT model based on the topographic file 11, soil database 12, meteorological database 13, and reservoir data 14 provided by the basin data module 1, as well as the land use and meteorological data of the basin, calculates the non-point source pollution load of each hydrological response unit in the basin, and outputs the calculation results as a txt file.

[0124] The EFDC model processing unit 42 is connected to the SWAT model processing unit 41 and is used to read the pollution load allocation ratio, out-flow rate, and riverbed sediment component data and initial concentration field data for river network hydrodynamic calculation. Specifically, the EFDC model processing unit 42 reads the non-point source pollutant load allocation ratio and the out-flow rate of each hydrological response unit output by the SWAT model processing unit 41, as well as the riverbed sediment component data and initial concentration field data, runs the EFDC model, performs river network hydrodynamic calculation, and outputs the calculation results as a csv file.

[0125] The dynamic TMDL allocation module 5 is connected to the hydrodynamic simulation module 4 and is used to realize the dynamic allocation of the total amount of basin pollutants based on the source-sink response simulation results. As Figure 5 shown, the dynamic TMDL allocation module 5 includes a load allocation ratio calculation unit 51, an actual total emission calculation unit 52, and an in-river load optimization unit 53.

[0126] The load allocation ratio calculation unit 51 is used to calculate the total amount of water taken at the water intake according to the calculated non-point source load allocation percentage, point source emission load allocation ratio, and the allocation coefficients of each water quality index.

[0127] Specifically, the load distribution ratio calculation unit 51 calculates using the following formula:

[0128] V total = ∑(V × C × W / C x ),

[0129] where V total is the total water intake of the water intake point, V is the water intake flow rate at a certain water intake point, C refers to the in-river load distribution ratio of the water quality index of this water intake point, W is the water intake volume during the water intake time of this water intake point, and C x is the water intake flow rate of water intake point x during the water intake time of the water intake point.

[0130] The actual emission total calculation unit 52 is connected to the load distribution ratio calculation unit 51 and is used to calculate the actual total emission of the water quality index within the map unit. Specifically, the actual emission total calculation unit 52 calculates using the following formula:

[0131] V' = ∑(α i × n i × β j ),

[0132] where α i represents the area of a certain map unit, n i represents the number of water intake points within this map unit, and β j represents the area of a certain water intake point.

[0133] The in-river load optimization unit 53 is connected to the actual emission total calculation unit 52 and is used to summarize the actual total emission of the water quality index and the emission distribution ratio, calculate the in-river load of this water quality index in the basin, and optimize the contribution ratio of all non-point sources within the basin. Specifically, the in-river load optimization unit 53 calculates the in-river load of the water quality index in the basin using the following formula:

[0134] V2' = ∑(V' × ω),

[0135] where ω is the adjustment coefficient, which is obtained by optimizing the contribution ratio of all non-point sources within the basin.

[0136] Preferably, the present invention further includes a source-sink response simulation module 6, which is used to construct data sequences of the input flow rates of each branch where pollutants flow into the main stream and the confluence of the intermediate reaches, and taking the river control section as a node, distribute the tributary and intermediate reach confluence flows to the corresponding main stream reaches of each river control section and the corresponding reaches of the estuary where they flow into the main stream.

[0137] The source-sink response simulation module 6 is also used to construct the runoff and water quality monitoring data of each river control section with the distributed SWAT model of the basin as the data platform and the monitored runoff mode as the control period; construct a pollution reduction scenario with the superposition of pollutant output and the change of water use type and a pollution control scenario with the superposition of land use type change.

[0138] Furthermore, the source-sink response simulation module 6 is also used to simulate the pollution distribution state of the upstream and downstream reaches of each section control surface based on the hydrodynamic model of EFDC through the pollutant output of each land use type on each section control surface; allocate the pollutant output to the main river network and tributary estuaries on each section control surface to form the simulated pollutant quantity of the pollutant section; calculate the difference between the sum of the pollutant cumulative input amounts of the river control section and the sum of the simulated pollutant section pollutant simulated quantities corresponding to each section control surface to form a pollution net load balance equation.

[0139] Specifically, the expression of the pollution net load balance equation is as follows:

[0140] Q i,r →Q j,s =T i,j +I i,i+1 +I i′,j ,

[0141] Wherein, Q i,r is the total pollutant net load of the upstream section i at the rth simulation time; Q j,s is the total pollutant net load of the downstream section j at the sth simulation time; T i,j represents the pollutant net load transfer amount from the upstream section i to the downstream section j; I i,i+1 represents the total pollutant net load input amount in the interval from the upstream section i to the upstream section i + 1; I i′,j represents the total pollutant net load input amount in the interval from the interval section i′ to the section j.

[0142] The calculation method of the interval pollution net load is as follows:

[0143] I i,j =∑(q i,r -q i,s +q i′,r ),

[0144] Wherein, i ∈ {i1, i2,..., i n},

[0145] j ∈ {j1, j2,..., j n},

[0146] r ∈ {1, 2,... n},

[0147] s∈{1,2,...n},

[0148] i+1≠j,n=34,

[0149] n is the total number of sections in the basin; q i,r Represents the net load input of pollutants upstream of the section; q i,s Indicates the net load output of pollutants downstream of the section; q i′,r It represents the net pollutant load input of the river section in the controlled watershed.

[0150] The net pollutant load equation is expressed as follows:

[0151] ΔQ=Q out -Q in =Q e +Q r ,

[0152] Among them, Q out Indicates the net load output of pollutants upstream of the section; Q in Indicates the net load input of pollutants downstream of the section; Q e It represents the net load generated by the exchange of water from rainfall, evaporation, irrigation and interception, which is the pollution source of the interval confluence; Q r It indicates the pollutant load generated in the river channel of the interval.

[0153] The present invention also provides a watershed pollution load accounting source-sink response simulation method based on the watershed pollution load accounting system. Figure 6 As shown, the following steps are included:

[0154] Step S1: Construct the coupling framework of SWAT model and EFDC model.

[0155] Step S11: Use the SWAT model to run with terrain files, soil database, meteorological database, reservoir data, and input land use and meteorological data of the basin.

[0156] Step S12: Calculate the non-point source pollution load of pollutants such as nitrogen and phosphorus caused by agricultural management that flow into each hydrological response unit in the basin.

[0157] Step S13: Read the total output Mout of non-point source pollutants in the hydrological response unit in each sub-basin in the SWAT model and the non-point source pollutant load distribution ratio Q, and calculate the non-point source pollution load into the river ratio. The calculation method is as follows:

[0158]

[0159] Among them, M represents the non-point source load into the river (t), Q represents the non-point source distribution ratio into the river, and M' represents the total non-point source load into the river (t). The total non-point source load into the river M' can be calculated by the following formula:

[0160]

[0161] Among them, M0 represents the total initial pollutant load into the river (t), and M1 to M 16 respectively refer to the pollutant loads (t) passing through different hydrological response units.

[0162] Step S14: Use the non-point source pollutant load distribution ratio and the outflow of each hydrological response unit as the inputs of the EFDC model.

[0163] Step S15: The EFDC model reads the pollution load distribution ratio Q, the outflow, the riverbed sediment component data, and the initial concentration field data for river network hydrodynamic calculation, and outputs the calculation results as a csv file.

[0164] Step S2: Integrate the non-point source pollution coefficient library and the point source emission inventory to achieve dynamic allocation of the total TMDL.

[0165] Step S21: Calculate the total water intake of the water intake according to the calculated non-point source load distribution percentage, the point source emission load distribution ratio, and the distribution coefficients of each water quality index.

[0166] Step S22: Calculate the actual total emission of the water quality index within the map unit according to the calculated total water intake.

[0167] Step S23: Summarize the actual total emission of the water quality index and the emission distribution ratio, and calculate the load into the river of the water quality index in the basin. The calculation method of the load distribution ratio of the water quality index into the river is as follows:

[0168]

[0169] Among them, Q represents the non-point source pollutant distribution ratio into the river, M represents the total non-point source load into the river in the basin, C represents the sum of the concentrations of each water intake, Q 总 represents the ratio of the water intake of each water intake, C 总 represents the sum of the concentrations of each water intake, D represents the ratio of the water intake of each water intake, C x represents the ratio of the water intake of the water intake.

[0170] Step S24: Optimize the contribution ratios of all non-point sources in the basin, adjust the contribution ratios of non-point sources in the basin, calculate the non-point source load distribution coefficients and point source load distribution coefficients of all hydrological response units, and achieve dynamic allocation of the total basin pollutants.

[0171] In practical applications, the systems and methods of the present invention can effectively support the decision-making for watershed water environment management. For example, in the practical application of a certain watershed, through the calculation of this system, the non-point source load allocation percentage of total nitrogen is 65%, and the point source emission load allocation ratio is 35%. After the TMDL allocation based on this, the emission reduction targets of each pollution source can be determined, providing a scientific basis for the improvement of the watershed water environment quality.

[0172] In addition, the systems and methods of the present invention can also simulate the changes in water environment quality under different management scenarios. For example, by simulating the implementation effects of agricultural non-point source pollution control measures (such as reducing the application amount of chemical fertilizers, improving irrigation methods, etc.), the improvement degree of these measures on the watershed water environment quality can be predicted, providing support for management decision-making.

[0173] In summary, the watershed pollution load accounting system and its source-sink response simulation method provided by the present invention, by constructing a coupling framework of the SWAT model and the EFDC model, integrating the non-point source pollution coefficient library and the point source emission inventory, realizing the dynamic allocation of the total TMDL amount, thus accurately accounting for the watershed pollution load and realizing the response simulation between the pollution source and the sink, providing scientific support for watershed water environment management. In particular, the present invention adopts the method with administrative villages as the smallest calculation unit, combines with the APCS-MLR non-point source pollution coefficient model, and realizes the accurate quantification of non-point source pollution; at the same time, through the dynamic TMDL allocation mechanism, realizes the scientific and dynamic allocation of the total amount of watershed pollutants, overcoming the limitations of the traditional static allocation method.

[0174] The systems and methods of the present invention are not only applicable to the current watershed water environment management practice, but also have broad application prospects. With the continuous improvement of environmental protection requirements and the continuous development of information technology, the present invention can further expand its functions, such as increasing the simulation ability for more pollutants, integrating climate change scenarios, predicting the impact of climate change on the watershed water environment, and combining with artificial intelligence technology to develop an intelligent water environment management decision support system.

[0175] It should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. Watershed pollution load accounting system, characterized in that, Including: A watershed data module for inputting watershed information and simulating hydraulic and water quality scenarios through a calculation model; A non-point source pollution module for simulating the non-point source pollution amounts of different land use types under the meteorological changes in the watershed; A point source emission module for accounting the point source pollution emissions in the watershed; A hydrodynamic simulation module, connected to the watershed data module, the non-point source pollution module and the point source emission module, for conducting hydrodynamic and water quality simulations by combining the watershed data and the boundary conditions input by meteorological driving; A dynamic TMDL allocation module, connected to the hydrodynamic simulation module, for realizing the dynamic allocation of the total amount of pollutants in the watershed based on the source-sink response simulation results.

2. The basin pollution load accounting system according to claim 1, wherein The watershed data module includes a topographic file, a soil database, a meteorological database and reservoir data for input, the watershed information includes watershed runoff, watershed land use types and watershed runoff model parameters, and the calculation model includes a coupling framework of the SWAT model and the EFDC model.

3. The basin pollution load accounting system according to claim 2, wherein The non-point source pollution module includes: A minimum administrative village calculation unit for extracting the area, administrative division boundary and land use type data of each administrative village in the watershed; An APCS-MLR non-point source pollution coefficient model, connected to the minimum administrative village calculation unit, for constructing a non-point source pollution coefficient calculation model of the watershed based on the land use type data; A non-point source load into river calculation unit, connected to the APCS-MLR non-point source pollution coefficient model, for calculating the contribution rate of non-point source pollutants into the river in the watershed.

4. The basin pollution load accounting system according to claim 2, wherein, The point source emission module includes: A point source type identification unit for identifying pollution sources in sewage outfalls, lakes, and the inflows of point source pollutants from agricultural activities, cities and industrial areas in the riparian zone and non-riparian zone; A point source total amount calculation unit, connected to the point source type identification unit, for calculating the total inflow load of point source pollutants according to the point source type.

5. The basin pollution load accounting system according to claim 2, wherein The hydrodynamic simulation module includes: A SWAT model processing unit for calculating the non-point source pollution load of pollutants such as nitrogen and phosphorus caused by agricultural chemical management into each hydrological response unit in the watershed; An EFDC model processing unit, connected to the SWAT model processing unit, for reading the pollution load distribution ratio, outflow, riverbed sediment component data and initial concentration field data for river network hydrodynamic calculation.

6. The basin pollution load accounting system according to claim 1, characterized in that, The dynamic TMDL allocation module includes: A load allocation ratio calculation unit for calculating the total amount taken by the water intake according to the calculated non-point source load allocation percentage, point source emission load allocation ratio and the allocation coefficient of each water quality index; An actual emission total amount calculation unit, connected to the load allocation ratio calculation unit, for calculating the actual emission total amount of water quality indicators within the map unit; An inflow load optimization unit, connected to the actual emission total amount calculation unit, for summarizing the actual emission total amount of water quality indicators and the emission allocation ratio, calculating the inflow load of the water quality indicator in the watershed, and optimizing the contribution ratio of all non-point sources in the watershed.

7. The basin pollution load accounting system according to claim 1, characterized in that It further includes a source-sink response simulation module, which is used to construct data sequences of input flow rates of pollutants flowing into the main stream through each branch and lateral inflow, and taking the river control sections as nodes, allocate the tributary and lateral inflow to the main stream reaches corresponding to each river control section and the reaches of the estuaries where the tributaries flow into the main stream.

8. The basin pollution load accounting system according to claim 7, wherein The source-sink response simulation module is further used for: Constructing runoff and water quality monitoring data of each river control section with the distributed SWAT model of the basin as the data platform and the monitored runoff mode as the control period; Constructing a pollution reduction scenario with the superposition of pollutant output and changes in water use types and a pollution control scenario with the superposition of land use type changes.

9. The basin pollution load accounting system according to claim 7, characterized in that, The source-sink response simulation module is further used for: Based on the hydrodynamic model of EFDC, simulating the pollution distribution status of the reaches upstream and downstream of each section control surface through the pollutant output of each land use type on each section control surface; Allocating the pollutant output to the main stream river network and tributary estuaries on each section control surface to form the simulated pollutant quantity of the section; Calculating the difference between the sum of the cumulative input amounts of pollutants at the river control section and the sum of the simulated pollutant quantities of the section corresponding to each section control surface to form a pollution net load balance equation.

10. A source-sink response simulation method for calculating the basin pollution load of the basin pollution load calculation system according to any one of claims 1-9, comprising the following steps: Constructing a coupling framework of the SWAT model and the EFDC model, including: Running the SWAT model with the topographic file, soil database, meteorological database, and reservoir data, and inputting the land use and meteorological data of the basin; Calculating the non-point source pollution load of pollutants such as nitrogen and phosphorus flowing into each hydrological response unit of the basin caused by agricultural chemical management; Reading the total output of non-point source pollutants in each sub-basin of the SWAT model on the hydrological response unit and the allocation ratio of the non-point source pollutant inflow load into the river, and calculating the non-point source pollution load inflow ratio; Taking the non-point source pollutant load allocation ratio and the outflow of each hydrological response unit as the input of the EFDC model; The EFDC model reads the pollution load allocation ratio, outflow, riverbed sediment component data, and initial concentration field data for river network hydrodynamic calculation; Integrating the non-point source pollution coefficient library and the point source emission inventory to achieve dynamic total amount allocation of TMDL, including: Calculating the total water intake of the water intake according to the calculated non-point source load allocation percentage, point source emission load allocation ratio, and the allocation coefficient of each water quality index; Calculating the actual total emission amount of the water quality index within the map unit according to the calculated total water intake; Summarizing the actual total emission amount of the water quality index and the emission allocation ratio, calculating the inflow load of the water quality index in the basin, and optimizing the contribution ratio of all non-point sources in the basin to achieve dynamic total amount allocation of basin pollutants.

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