Construction method and device of agricultural watershed non-point source pollution decision support system

Abstract

The invention relates to the technical field of pollution analysis, in particular to a construction method and device of an agricultural watershed non-point source pollution decision support system.The construction method of the agricultural watershed non-point source pollution decision support system comprises the steps that firstly, the nitrogen and phosphorus loss amount of each pollution source is calculated; acquiring digital elevation data; determining an intermediate water body between each pollution source and the target water body according to the digital elevation data, and obtaining a migration path corresponding to each pollution source; when the absorption amount of each migration path is determined, the water body type is considered, and the influence of the difference between the hydraulic characteristics and the physicochemical properties of the water body on the absorption amount can be reflected through the water body type, so that the calculated absorption amount of each migration path is more accurate; furthermore, the target water body considers the complex communication relation and topological relation among the ditch, the pond, the reservoir and the river, and the simulated water body load capacity is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of pollution analysis, and in particular to a construction method and device of a decision support system for agricultural watershed non-point source pollution. Background Art

[0002] Non-point source pollution in river basins is one of the major challenges facing current water environment management. Its characteristics are dispersed pollution sources, multiple types of pollutants, and complex migration paths. The decision support system for non-point source pollution in river basins builds a non-point source pollution model based on the environmental characteristics of the river basin, analyzes, predicts, simulates and plans the current status and changing trends of non-point source pollution in the river basin, and aims to help governments and environmental management departments to timely warn of environmental risks, analyze the causes of pollution, reduce pollution loads, and thus comprehensively improve the management level of non-point source pollution. The decision support system plays a decisive role in the efficient prevention and control of non-point source pollution.

[0003] Internationally, the research and development of non-point source pollution decision support systems started early, and a series of mature models have been formed, such as SPARROW, AGNPS, SWAT, etc. These models have been widely used around the world. They provide a scientific basis for the prediction, assessment and management of non-point source pollution by simulating the hydrological process, material migration and transformation process in the basin. However, these models have certain limitations when applied to China, mainly manifested in the lack of consideration of my country's unique multi-water agricultural characteristics and complex hydrogeological conditions. In my country, although some progress has been made in non-point source nitrogen and phosphorus simulation and decision support based on the Xin'anjiang River Basin hydrological model, there is still a clear gap compared with mature decision support systems abroad.

[0004] Existing models often have the following shortcomings when simulating the non-point source nitrogen and phosphorus loss pattern, migration pathways, and along-the-way absorption processes in complex agricultural areas with multiple water bodies in the south: When simulating the absorption process, a single absorption coefficient is usually used, which fails to fully consider the hydraulic characteristics and physical and chemical property differences of the water body. Summary of the invention

[0005] In view of this, the present invention provides a decision support system for agricultural watershed non-point source pollution to solve the problem of failing to fully consider the hydraulic characteristics and physical and chemical property differences of water bodies when simulating the absorption process.

[0006] In the first aspect, the present invention provides a method for constructing a decision support system for non-point source pollution in an agricultural watershed, comprising the following steps: obtaining all pollution sources that flow into a target water body, and calculating the nitrogen and phosphorus losses of each pollution source; obtaining digital elevation data; determining the intermediate water bodies between each pollution source and the target water body based on the digital elevation data, and obtaining the migration paths corresponding to each pollution source; respectively determining the type of each intermediate water body, and determining the absorption capacity of each migration path based on the type of each intermediate water body; obtaining the load of the target water body based on the nitrogen and phosphorus losses of each pollution source and the absorption capacity of the migration path corresponding to each pollution source; and constructing a decision support system for non-point source pollution in an agricultural watershed based on the loads of multiple target water bodies.

[0007] The method for constructing a decision support system for agricultural watershed non-point source pollution provided by the present invention comprises the following steps: firstly, all pollution sources flowing into a target water body are obtained, and the nitrogen and phosphorus loss of each pollution source is calculated; digital elevation data is obtained; the intermediate water body between each pollution source and the target water body is determined according to the digital elevation data, and a migration path corresponding to each pollution source is obtained; when determining the absorption amount of each migration path, the water body type is taken into consideration, and the influence of the hydraulic characteristics and physical and chemical property differences of the water body on the absorption amount can be reflected by the water body type, so that the absorption amount of each migration path calculated thereby is more accurate, and thus the load amount of the target water body obtained thereby is more accurate; and the intermediate water body between each pollution source and the target water body is determined according to the digital elevation data, and a migration path corresponding to each pollution source is obtained, and the complex connectivity and topological relationships among ditch, pond, reservoir and river are taken into consideration.

[0008] In an optional embodiment, calculating the nitrogen and phosphorus loss of each pollution source includes: when the pollution source is a planting source, for each pollution source i, determining the type of pollution source i; according to the type of pollution source i, determining the amount of water withdrawal from pollution source i; calculating the nitrogen and phosphorus concentrations in the withdrawal water from pollution source i; determining the nitrogen and phosphorus loss of pollution source i based on the withdrawal water amount of pollution source i and the nitrogen and phosphorus concentrations in the withdrawal water from pollution source i.

[0009] That is to say, when the pollution source is a planting source, the pollution source is further divided, and based on the division results, the water withdrawal amount and nitrogen and phosphorus concentration of each type of plantation are calculated separately, and the nitrogen and phosphorus loss of each type of plantation is further obtained, thereby making the calculated nitrogen and phosphorus loss of the plantation more accurate.

[0010] In an optional embodiment, according to the type of pollution source i, determining the amount of water withdrawn from pollution source i includes: when the pollution source i is a dry field, obtaining the first precipitation, first irrigation amount, soil evaporation, first crop transpiration, groundwater recharge, deep seepage, and soil water storage change of the pollution source i; calculating the amount of water withdrawn from pollution source i according to the first precipitation, first irrigation amount, soil evaporation, first crop transpiration, groundwater recharge, deep seepage, and soil water storage change; when the pollution source i is a paddy field, obtaining the second precipitation, second irrigation amount, field surface evaporation, and second crop transpiration of the pollution source i; and calculating the amount of water withdrawn from pollution source i according to the second precipitation, second irrigation amount, field surface evaporation, and second crop transpiration.

[0011] That is to say, when the pollution source is a planting source, the pollution source is further divided into dry land and paddy field, and the water withdrawal of each type of planting source is calculated separately, so that the calculated water withdrawal of the planting source can be more accurate; and it comprehensively considers the differences in pollutant generation patterns between dry land and paddy fields, based on water balance and soil physical and chemical adsorption theory, not only the physical mechanism is clear, but also the required parameters are few.

[0012] In an optional embodiment, the type of each intermediate water body is determined separately, and the absorption capacity of each migration path is determined according to the type of each intermediate water body, including: determining the proportion of upstream pollutants received by each intermediate water body according to the type of each intermediate water body; and obtaining the absorption capacity of each migration path according to the nitrogen and phosphorus loss of each pollution source, the migration path corresponding to each pollution source, and the proportion of upstream pollutants received by each intermediate water body.

[0013] That is to say, when determining the absorption capacity of each migration path, the proportion of upstream pollutants received by the water body is determined according to the type of water body. The proportion of upstream pollutants received by the water body can reflect the impact of the hydraulic characteristics and physical and chemical properties of the water body on the absorption capacity. The absorption capacity of each migration path calculated in this way is more accurate, and the load of the target water body is more accurate.

[0014] In an optional embodiment, determining the proportion of upstream pollutants received by each intermediate water body according to the type of each intermediate water body includes: when the intermediate water body is a linear water body, obtaining the number of linear water bodies in the migration path to which the intermediate water body belongs, the path length from the pollution source corresponding to the intermediate water body to the intermediate water body, the hydraulic radius from the pollution source corresponding to the intermediate water body to the intermediate water body, the slope from the pollution source corresponding to the intermediate water body to the intermediate water body, and the depth of the intermediate water body; calculating the proportion of upstream pollutants received by the intermediate water body according to the number of linear water bodies in the migration path to which the intermediate water body belongs, the path length, the hydraulic radius, the slope and the depth; when the intermediate water body is a planar water body, obtaining the total area of ​​the planar water area of ​​the migration path to which the intermediate water body belongs; and calculating the proportion of upstream pollutants received by the intermediate water body according to the total area of ​​the planar water area.

[0015] That is to say, water bodies are divided into linear water bodies and surface water bodies, and different calculation methods are used for linear water bodies and surface water bodies to calculate the proportion of upstream pollutants received by the water bodies. In this way, the calculated proportion of upstream pollutants received by the water bodies can reflect the impact of the hydraulic characteristics and physical and chemical properties of the water bodies on the absorption capacity.

[0016] In an optional embodiment, the absorption capacity of each migration path is obtained based on the nitrogen and phosphorus loss of each pollution source, the migration path corresponding to each pollution source, and the proportion of upstream pollutants received by each intermediate water body, including: for migration path n, determining the pollution source m corresponding to migration path n, and all intermediate water bodies between the pollution source m and the target water body in the migration path n; obtaining the absorption capacity of migration path n using the nitrogen and phosphorus loss of pollution source m and the proportion of upstream pollutants received by all intermediate water bodies between the pollution source m and the target water body; traversing all migration paths to obtain the absorption capacity of each migration path.

[0017] In other words, when calculating the absorption capacity of each migration path, the topological and connection relationships between water bodies and water bodies, and between water bodies and land plots are fully considered, which can accurately simulate the migration and absorption process of pollutants in the watershed.

[0018] In a second aspect, the present invention further provides a decision support system for agricultural watershed non-point source pollution, which is constructed using the method for constructing a decision support system for agricultural watershed non-point source pollution of the first aspect or any corresponding embodiment thereof.

[0019] In the second aspect, the present invention provides a construction device for a decision support system for non-point source pollution in an agricultural watershed, the device comprising a first acquisition module, a nitrogen and phosphorus loss calculation module, a second acquisition module, a migration path determination module, a migration path absorption capacity determination module, a load determination module and a system construction module; the first acquisition module is used to obtain all pollution sources that flow into a target water body; the nitrogen and phosphorus loss calculation module is used to calculate the nitrogen and phosphorus loss of each pollution source; the second acquisition module is used to obtain digital elevation data; the migration path determination module is used to determine the intermediate water body between each pollution source and the target water body according to the digital elevation data, and obtain the migration path corresponding to each pollution source; the migration path absorption capacity determination module is used to respectively determine the type of each intermediate water body, and determine the absorption capacity of each migration path according to the type of each intermediate water body; the load determination module is used to obtain the load of the target water body according to the nitrogen and phosphorus loss of each pollution source and the absorption capacity of the migration path corresponding to each pollution source; the system construction module is used to construct a decision support system for non-point source pollution in an agricultural watershed according to the load of multiple target water bodies. 。

[0020] In a third aspect, the present invention provides a computer device comprising a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to execute the method for constructing a decision support system for agricultural watershed non-point source pollution according to the first aspect or any corresponding embodiment thereof.

[0021] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the method for constructing a decision support system for agricultural watershed non-point source pollution according to the first aspect or any corresponding embodiment thereof.

[0022] In a fifth aspect, the present invention provides a computer program product, comprising computer instructions, which are used to enable a computer to execute the method for constructing a decision support system for agricultural watershed non-point source pollution according to the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 is a flow chart of a method for constructing a decision support system for agricultural watershed non-point source pollution according to an embodiment of the present invention;

[0025] Figure 2 is a flow chart of another method for constructing an agricultural watershed non-point source pollution decision support system according to an embodiment of the present invention;

[0026] Figure 3 is a schematic diagram of the results of a field occurrence model and a watershed migration model according to an embodiment of the present invention;

[0027] Figure 4 This is the result map of the analysis of the source area of ​​the small watershed of Jurong Reservoir;

[0028] Figure 5 This is the risk assessment result map of Qinhuai River Basin;

[0029] Figure 6 It is a decision support tool for identifying the path of the small watershed of Jurong Reservoir and its operation effect diagram;

[0030] Figure 7 It is a decision support tool for the site selection of farms in the small watershed of Jurong Reservoir and an operation effect diagram;

[0031] Figure 8 It is a decision support tool for the planning of small watershed wetlands in Jurong Reservoir and an operational effect diagram;

[0032] Fig. 9 is a structural block diagram of a construction device of an agricultural watershed non-point source pollution decision support system according to an embodiment of the present invention;

[0033] Fig.10 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0035] The existing domestic models often have the following deficiencies when simulating the absorption process of non-point sources along the way in my country's complex multi-water-body agricultural areas: 1) The merging and generalization of water landscape units. When dealing with water landscape units, the existing models tend to merge and generalize small water bodies, such as ponds, while ignoring the important role of these small water bodies in the process of non-point source pollution. 2) The singleness of the absorption process. When simulating the absorption process, a single absorption coefficient is usually used, and the hydraulic characteristics and physical and chemical properties of the water body are not fully considered. 3) Simplification of migration paths. When calculating the water flow path, digital elevation models and water balance methods are often used, while ignoring the complex connectivity and topological relationships between ditches, ponds, reservoirs and rivers.

[0036] Based on this, an embodiment of the present invention provides an embodiment of a method for constructing an agricultural watershed non-point source pollution decision support system. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0037] In this embodiment, a method for constructing an agricultural watershed non-point source pollution decision support system is provided, which can be used in computer equipment. Figure 1 is a flow chart of a method for constructing a decision support system for agricultural watershed non-point source pollution according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0038] Step S101: Obtain all pollution sources that flow into the target water body and calculate the nitrogen and phosphorus loss of each pollution source.

[0039] Step S102: Acquire digital elevation data.

[0040] Step S103: determining the intermediate water body between each pollution source and the target water body according to the digital elevation data, and obtaining the migration path corresponding to each pollution source.

[0041] Step S104: Determine the type of each intermediate water body respectively, and determine the absorption capacity of each migration path according to the type of each intermediate water body.

[0042] Step S105: Obtain the load of the target water body according to the nitrogen and phosphorus loss of each pollution source and the absorption amount of the migration path corresponding to each pollution source;

[0043] Step S106: constructing an agricultural watershed non-point source pollution decision support system according to the loads of multiple target water bodies.

[0044] The construction method of the agricultural watershed non-point source pollution decision support system of this embodiment first obtains all pollution sources that flow into the target water body and calculates the nitrogen and phosphorus losses of each pollution source; obtains digital elevation data; determines the intermediate water body between each pollution source and the target water body based on the digital elevation data, and obtains the migration path corresponding to each pollution source; when determining the absorption capacity of each migration path, the water body type is taken into account, and the water body type can reflect the influence of the hydraulic characteristics and physical and chemical property differences of the water body on the absorption capacity, so that the absorption capacity of each migration path calculated is more accurate, and thus the load of the target water body is more accurate; and the intermediate water body between each pollution source and the target water body is determined based on the digital elevation data to obtain the migration path corresponding to each pollution source, taking into account the complex connectivity and topological relationships between ditches, ponds, reservoirs and rivers.

[0045] Based on the method for determining the water body load in this embodiment, a non-point source pollution decision support system that is more suitable for the characteristics of the multi-water agricultural basin in the south can be constructed. The system should be able to accurately simulate the generation, migration and absorption process of non-point source pollutants, and at the same time have the characteristics of few parameter requirements, simple operation, visual results, and reliable simulation results. In addition, the system should also be able to provide the government and environmental management departments with functions such as non-point source pollution status analysis, risk warning, and pollution load reduction plan formulation to support accurate management and scientific decision-making of non-point source pollution.

[0046] In this embodiment, a method for constructing an agricultural watershed non-point source pollution decision support system is provided, which can be used in computer equipment. Figure 2 FIG. 4 is a flow chart of another method for constructing an agricultural watershed non-point source pollution decision support system according to an embodiment of the present invention. Figure 2 As shown, the process includes the following steps:

[0047] Step S201: Obtain all pollution sources that flow into the target water body and calculate the nitrogen and phosphorus losses of each pollution source.

[0048] In an optional embodiment, calculating the nitrogen and phosphorus loss of each pollution source includes the following steps:

[0049] Step S2011: When the pollution source is a planting source, for each pollution source i, determine the type of pollution source i.

[0050] Step S2012: Determine the water withdrawal amount of pollution source i according to the type of pollution source i.

[0051] Specifically, when the pollution source i is a dry field, the first precipitation, the first irrigation amount, the soil evaporation, the first crop transpiration, the groundwater recharge, the deep seepage, and the change in soil water storage of the pollution source i are obtained; and the water withdrawal amount of the pollution source i is calculated according to the first precipitation, the first irrigation amount, the soil evaporation, the first crop transpiration, the groundwater recharge, the deep seepage and the change in soil water storage.

[0052] When the pollution source i is a paddy field, the second precipitation, the second irrigation amount, the field surface evaporation and the second crop transpiration of the pollution source i are obtained; and the water withdrawal amount of the pollution source i is calculated according to the second precipitation, the second irrigation amount, the field surface evaporation and the second crop transpiration.

[0053] Step S2013: Calculate the nitrogen and phosphorus concentrations in the return water from pollution source i.

[0054] Step S2014: Determine the nitrogen and phosphorus loss of pollution source i based on the water discharge volume of pollution source i and the nitrogen and phosphorus concentrations in the discharge water of pollution source i.

[0055] In this embodiment, the decision support system for non-point source pollution in southern agricultural watersheds includes a field occurrence model and a watershed migration model. Among them, the purpose of constructing the field occurrence model is to construct a non-point source pollution occurrence model at the field level to simulate the generation and loss process of non-point source pollution in farmland. Factors considered in the field occurrence model include: land use type, soil type, crop planting pattern, fertilization habits, etc. The model characteristics of the field occurrence model are: comprehensive consideration of the differences in pollutant generation patterns between dryland and paddy fields, based on water balance and soil physical and chemical adsorption theory, not only the physical mechanism is clear, but also the required parameters are few.

[0056] The purpose of constructing a watershed migration model is to develop a watershed migration model to simulate the migration path and absorption process of non-point source pollutants in the watershed. The factors considered in the watershed migration model include: surface runoff, subsoil flow, base flow, etc., as well as the absorption and hydraulic characteristics of different water body types, especially small water bodies (such as ditches, ponds, rivers, and lakes). The model features of the watershed migration model include: fully considering the topological and connection relationship between water bodies and water bodies, and water bodies and land plots, and being able to accurately simulate the migration and absorption process of pollutants in the watershed.

[0057] Figure 3 Schematic diagram of the results of the field occurrence model and the watershed migration model according to an embodiment of the present invention. Figure 3 As shown in Figure 1, the generation and loss process of farmland non-point source pollution can be simulated through the field occurrence model. Among them, the factors considered in the field occurrence model include: land use type, soil type, crop planting pattern, fertilization habits, etc.

[0058] The field occurrence model includes the simulation of water withdrawal and nitrogen and phosphorus concentration in the withdrawn water. Based on the theory of water balance and soil physical and chemical adsorption, the models of water withdrawal and nitrogen and phosphorus concentration in the withdrawn water of dryland and paddy fields are used to estimate the loss of nitrogen and phosphorus from farmland. The simulation of water withdrawal is calculated separately according to different irrigation modes of dryland (such as corn and wheat) and paddy fields (such as rice) using the water balance equation. The concentration of nitrogen and phosphorus in the withdrawn water of farmland is simulated by constructing a model of fertilizer application amount, water withdrawal time and soil nitrogen and phosphorus balance concentration.

[0059]

[0060] In the above formula: L represents the total amount of nitrogen and phosphorus loss from regional farmland, kg; A i represents the irrigated area of ​​farming type i, hm 2 ; R represents the amount of water withdrawal, m 3 ·hm -2 ; C represents the nitrogen and phosphorus concentration in the drained water, mg·L -1 ; 0.001 is the dimension conversion coefficient.

[0061] 1) Calculation of water withdrawal

[0062] Since dry land is irrigated in different irrigation periods, while paddy fields are irrigated throughout the entire growing period, the water withdrawal is calculated separately through the water balance equation based on the different irrigation modes of dry land and paddy fields.

[0063] The unit area of ​​the vadose zone column is taken as the water balance calculation unit, the upper interface is the ground surface, and the lower interface is selected as the water table. The input items of soil water include precipitation, irrigation water, lateral recharge, and deep recharge. The output items of soil water include evaporation, lateral drainage, deep seepage, and plant transpiration. Since the horizontal flow of soil water in the irrigation area is very weak, lateral recharge and drainage are not considered. Therefore, the water withdrawal can be expressed by the following model:

[0064] R=P+IE-T+Du-Dd-ΔSW

[0065] Where: R is the amount of water withdrawal, mm; P is the amount of precipitation, mm; I is the amount of irrigation, mm; E is the amount of soil evaporation, mm; T is the amount of crop transpiration, mm; D u is the groundwater recharge, mm; D d is the deep seepage volume, mm; △SW is the change in soil water storage, mm.

[0066] Since most of the soil in the paddy field is saturated with water, the groundwater level is high, and the soil moisture changes little, the water balance only considers field evaporation, crop transpiration (together known as ET), irrigation, and rainfall. The amount of water withdrawal is calculated by the following formula:

[0067] R=P+I-ET

[0068] Only after the irrigation of the rice fields ends during the maturity period, the groundwater level drops rapidly due to evaporation and gravity and the lack of irrigation replenishment, and the soil moisture content drops sharply, at which time the water withdrawal amount is 0.

[0069] 2) Nitrogen and phosphorus concentration simulation

[0070] The nitrogen and phosphorus concentrations in the drainage are related to the amount of fertilizer applied, the time of drainage, and the soil equilibrium concentration. In the early stage of fertilization, the nitrogen and phosphorus concentrations in the soil are the highest, but at this time the soil also adsorbs nitrogen and phosphorus the fastest, and the nitrogen and phosphorus conversion process is the fastest. As the amount of soil adsorption increases, the adsorption rate gradually decreases, and the nitrogen and phosphorus conversion process and adsorption process gradually slow down, and finally reach a state of equilibrium. The entire process can be simulated by a power exponential decline function.

[90] :

[0071] C=a1F×exp(-d1t)+c1

[0072] Where: C is the concentration in the water, mg·L -1 , F is the amount of fertilizer applied, kg·hm -2 ; a1, d1 are parameters; t is the number of days from runoff generation to irrigation, d; c1 is the equilibrium concentration, mg·L -1 .

[0073] For the estimation of breeding sources, the average number of livestock and poultry raised in a year should be determined according to the conditions of each type of livestock and poultry. In addition, the breeding period of livestock and poultry should be taken into consideration. As for the daily production of manure and urine per head, it can be determined by referring to the daily discharge parameters of livestock and poultry manure at home and abroad.

[0074] That is to say, when the pollution source is a planting source, the pollution source is further divided into dry fields and paddy fields, and the water withdrawal of each type of plantation is calculated separately, so that the calculated water withdrawal of the plantation can be more accurate; and it comprehensively considers the differences in pollutant generation patterns between dry land and paddy fields, based on water balance and soil physical and chemical adsorption theory, not only the physical mechanism is clear, but also the required parameters are few.

[0075] Annual feces production = daily feces production of individuals (kg·d-1·head-1) × feeding period (d) × number of animals raised (heads, pieces)

[0076] Annual urine production = daily urine production of individuals (kg·d-1·head-1) × breeding period (d) × number of breeding (heads, pieces)

[0077] For the estimation of life sources, it is estimated based on the population equivalent load. Through surveys or statistical yearbooks, the population of the area and the amount of ammonia nitrogen, nitrogen and phosphorus produced per person per day can be determined, so as to estimate the amount of rural life pollution load.

[0078] Step S202: Acquire digital elevation data.

[0079] Step S203: Determine the intermediate water body between each pollution source and the target water body according to the digital elevation data, and obtain the migration path corresponding to each pollution source. Specifically, the D8 algorithm is used, which divides the watershed into several grids. For pollutants on any grid in the watershed, they migrate with the water flow method, where the water flow direction is determined by the grid with the lowest terrain among the surrounding 8 grids. If the maximum descent direction of multiple grids is the same, the range of adjacent pixels will be expanded until the steepest descent direction is found.

[0080] Step S204: Determine the type of each intermediate water body respectively, and determine the absorption capacity of each migration path according to the type of each intermediate water body.

[0081] In an optional implementation, determining the type of each intermediate water body respectively, and determining the absorption capacity of each migration path according to the type of each intermediate water body includes the following steps:

[0082] Step S2041: Determine the proportion of upstream pollutants received by each intermediate water body according to the type of each intermediate water body.

[0083] Specifically, when the intermediate water body is a linear water body, the number of linear water bodies in the migration path to which the intermediate water body belongs, the path length from the pollution source corresponding to the intermediate water body to the intermediate water body, the hydraulic radius from the pollution source corresponding to the intermediate water body to the intermediate water body, the slope from the pollution source corresponding to the intermediate water body to the intermediate water body, and the depth of the intermediate water body are obtained; the proportion of upstream pollutants received by the intermediate water body is calculated according to the number of linear water bodies in the migration path to which the intermediate water body belongs, the path length, the hydraulic radius, the slope and the depth. Specifically, a linear water body is a water body whose width is negligible relative to its length, such as a ditch, a river, etc.

[0084] Specifically, when the intermediate water body is a planar water body, the total area of ​​the planar waters of the migration path to which the intermediate water body belongs is obtained; and the proportion of upstream pollutants received by the intermediate water body is calculated according to the total area of ​​the planar waters. Specifically, the planar water body is a water body whose width relative to the length cannot be ignored, such as a pond, a reservoir, a lake, etc.

[0085] For example, R l and R a They respectively represent the proportion of upstream pollutants received by linear water body LW and surface water body AW.

[0086] From R = e -k已 It can be seen that the proportion of upstream pollutants received by linear water bodies LW and surface water bodies AW is determined by the hydraulic retention time (τ) and the pollutant elimination rate constant (k).

[0087] For a linear water body LW, assuming the hydraulic retention time τ l With the hydraulic path length Li increases with the increase of the hydraulic path slope s i,j Therefore, it can be calculated by the following formula:

[0088]

[0089] Where n is the number of linear water bodies along the hydraulic path of pollutant i, l i,j , R i,j and i,j are the path length, hydraulic radius and average slope of the pollutant migration from source i to location j; L l,i represents the total length of migration; l i,j represents the migration length on each grid cell, L l,i Yes i,j The sum of the migration distances on each grid. According to Chezy's open channel homogeneous flow equation, C is the Chezy constant (n, between 0.02-0.05) related to the Manning roughness coefficient. R is the hydraulic radius or hydraulic depth, which can be calculated by dividing the cross-sectional area of ​​the water flow by the perimeter LW. In order to avoid the equation result appearing infinite, we choose 0.005 as the minimum slope value.

[0090] For the surface water body AW, assuming that the total hydraulic retention time (τ a ) depends on the total area of ​​surface waters that the nutrients pass through on their migration path (A a ):

[0091]

[0092] Among them, coefficients β1 and β2 were derived based on a global meta-analysis data, with values ​​of 1.50 and 0.23 respectively.

[0093] For AWs, meta-analysis and model simulation results show that the primary pollutant elimination rate constant (k a ) and hydraulic retention time (τ a ) has a significant positive correlation, and the primary pollutant elimination rate constant can be calculated by the following formula:

[0094]

[0095] In the formula, c a , d a It is a constant with a value between 0.31 and 0.45, and between -0.86 and -0.7.

[0096] For linear water bodies, water depth can well explain the linear water body first-order absorption rate constant (k l )’s variation:

[0097]

[0098] Where D is the average water depth of the linear water body (m), and the empirical coefficient c l Take 0.0513, d l Take 1.319. If the water depth parameters of some river sections are not available, the average water depth of the river section is calculated based on the empirical formula inferred from 374 observation stations in the United States:

[0099] D=0.2396Q 0.4363

[0100] Among them, Q is the river flow, which is calculated by the runoff curve method (SCS-CN) developed by the Soil Conservation Service of the United States Department of Agriculture, which takes into account the influence of soil properties, land use, vegetation cover and other characteristics on the river flow.

[0101] For the geographical parameters (s i,j ,l i,j ,A aj ), which can be easily calculated using standard GIS software (such as ArcGIS). However, the cumulative area / length of the pollutant flowing through the water body The parameter calculation process is relatively complicated.

[0102] The eight-direction (D8) algorithm and recursive algorithm are used to identify the cumulative area of ​​pollutants flowing through the surface water bodies (AWs) and the cumulative length of pollutants flowing through the linear water bodies (LWs) from each grid cell. Due to the different nested structures, the calculation process of AWs and LWs is slightly different. For AWs, the cumulative area of ​​AWs and the cumulative migration length of linear water bodies between AWs are calculated separately.

[0103] That is to say, when determining the absorption capacity of each migration path, the water body is divided into linear water bodies and surface water bodies. Different calculation methods are used for linear water bodies and surface water bodies to calculate the proportion of upstream pollutants received by the water body. In this way, the calculated proportion of upstream pollutants received by the water body can reflect the impact of the hydraulic characteristics and physical and chemical properties of the water body on the absorption capacity. The absorption capacity of each migration path calculated in this way is more accurate, and thus the load of the target water body is more accurate.

[0104] Step S2042: The absorption capacity of each migration path is obtained according to the nitrogen and phosphorus loss of each pollution source, the migration path corresponding to each pollution source, and the proportion of upstream pollutants received by each intermediate water body.

[0105] Step S205: Obtain the load of the target water body according to the nitrogen and phosphorus loss of each pollution source and the absorption capacity of the migration path corresponding to each pollution source.

[0106] In an optional embodiment, obtaining the load of the target water body according to the nitrogen and phosphorus loss of each pollution source and the absorption amount of the migration path corresponding to each pollution source includes the following steps:

[0107] Step S2051: for migration path n, determine the pollution source m corresponding to the migration path n, and all intermediate water bodies between the pollution source m and the target water body in the migration path n;

[0108] Step S2052: using the nitrogen and phosphorus loss of pollution source m and the proportion of upstream pollutants received by all intermediate water bodies between pollution source m and the target water body, the absorption capacity of migration path n is obtained;

[0109] Step S2053: traverse all migration paths to obtain the absorption capacity of each migration path.

[0110] Step S206: constructing an agricultural watershed non-point source pollution decision support system according to the loads of multiple target water bodies.

[0111] Based on the method for determining the water body load in this embodiment, a non-point source pollution decision support system that is more suitable for the characteristics of multi-water agricultural basins in the south can be constructed. The non-point source pollution decision support system can realize decision support functions such as source area analysis, risk assessment, path identification, farm site selection, and wetland planning; it can provide intuitive simulation and evaluation results display to enhance decision makers' understanding of the pollution situation. It can formulate pollution load reduction plans for governments and environmental management departments, and support precise management and scientific decision-making of non-point source pollution.

[0112] Figure 4 This is the result of the analysis of the source area of ​​the small watershed of Jurong Reservoir. Figure 4 As shown, the source loss in a certain area was 71.6 tons, the intermediate water bodies (including ditches, ponds, rivers, and reservoirs) absorbed 50.7 tons, and the final downstream load was 20.9 tons.

[0113] Figure 5 This is the result of the risk assessment of the Qinhuai River Basin. Figure 5 Different colors represent different levels of risk.

[0114] Figure 6 It is a decision support tool for identifying the small watershed path of Jurong Reservoir and the operation effect diagram, such as Figure 6 As shown in the figure, the pollution sources at three different locations are all 100kg / N. After passing through different paths, the final water quality loads are 85kg / N, 77kg / N and 94kg / N respectively. In other words, the pollution sources at different locations, with the same discharge amount, will have different final water quality loads due to the differences in paths.

[0115] Figure 7It is a decision support tool for the site selection of farms in the Jurong Reservoir small watershed and an operation effect diagram. Figure 7 In the figure, different colors represent different water quality loads. Farms will discharge nutrients. Under the same discharge adjustment, they will give priority to areas with small water quality loads.

[0116] Figure 8 It is a decision support tool for the planning of small watershed wetlands in Jurong Reservoir and an operation effect diagram. Figure 8 The green areas show the area of ​​wetlands that would be required in each region to reduce the load by 10%.

[0117] In summary, the non-point source pollution decision support system has the following functions:

[0118] (1) Source area analysis

[0119] Conduct generation-consumption-load simulation to identify hotspots of non-point source pollution. This function helps decision makers understand high-risk areas of pollution through refined simulation, so as to allocate resources and take management measures more effectively.

[0120] (2) Risk Assessment

[0121] When it is difficult to obtain parameters and directly calculate the amount of occurrence, non-point source pollution risk assessment is carried out by evaluating the potential for occurrence and the amount consumed along the way.

[0122] The occurrence potential can be determined by the land use output coefficient or expert scoring, and the risk level is divided into percentiles, with level 9 representing the highest risk and level 0 representing the lowest risk.

[0123] The input parameters of risk assessment include water body distribution vector data, digital elevation (DEM) data, land use vector data, and occurrence potential vector data.

[0124] (3) Path identification

[0125] For any pollution source in the watershed, the runoff volume and nitrogen and phosphorus concentrations are simulated to further identify the pollutant migration path and evaluate its load along the way.

[0126] The input parameters for path identification include digital elevation (DEM) data, pollution source vector data (including location and source strength), and absorption coefficient raster data.

[0127] (4) Farm site selection

[0128] The load changes when the same amount of pollutants are added in the basin are simulated to determine the best location for the farm; the greater the load increase, the lower the site priority; conversely, the higher the priority.

[0129] The input parameters for farm selection include occurrence raster layer, absorption coefficient raster layer, and digital elevation (DEM) data.

[0130] (5) Wetland planning

[0131] Based on the set water quality improvement goals and the absorption efficiency of ecological wetlands, key river sections are selected for wetland planning.

[0132] When the cumulative pollutant load in a river section reaches or exceeds the water quality target value, the required wetland area is calculated through the wetland absorption efficiency to achieve water quality improvement.

[0133] The input parameters of wetland planning include occurrence raster layer, absorption coefficient raster layer, digital elevation (DEM) data, set water quality targets, and ecological wetland absorption efficiency.

[0134] In the present embodiment, a construction device for a decision support system for non-point source pollution in an agricultural watershed is also provided, and the device is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can implement a combination of software and / or hardware of a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware is also possible and conceived.

[0135] This embodiment provides a device for constructing a decision support system for agricultural watershed non-point source pollution. Fig. 9 As shown, including:

[0136] The first acquisition module 901 is used to acquire all pollution sources flowing into the target water body.

[0137] The nitrogen and phosphorus loss calculation module 902 is used to calculate the nitrogen and phosphorus loss of each pollution source.

[0138] The second acquisition module 903 acquires digital elevation data.

[0139] The migration path determination module 904 is used to determine the intermediate water body between each pollution source and the target water body according to the digital elevation data, and obtain the migration path corresponding to each pollution source.

[0140] The migration path absorption capacity determination module 905 is used to determine the type of each intermediate water body respectively, and determine the absorption capacity of each migration path according to the type of each intermediate water body.

[0141] The load determination module 906 is used to obtain the load of the target water body according to the nitrogen and phosphorus loss of each pollution source and the absorption amount of the migration path corresponding to each pollution source;

[0142] The system construction module 907 is used to construct an agricultural watershed non-point source pollution decision support system according to the load of multiple target water bodies.

[0143] In an optional embodiment, the nitrogen and phosphorus loss calculation module 902 includes a pollution source type determination unit, a water withdrawal determination unit, a nitrogen and phosphorus concentration determination unit, and a nitrogen and phosphorus loss determination unit. Among them, the pollution source type determination unit is used to determine the type of pollution source i for each pollution source i when the pollution source is a planting source; the water withdrawal determination unit is used to determine the water withdrawal amount of pollution source i according to the type of pollution source i; the nitrogen and phosphorus concentration determination unit is used to calculate the nitrogen and phosphorus concentration in the water withdrawal of pollution source i; the nitrogen and phosphorus loss determination unit is used to determine the nitrogen and phosphorus loss of pollution source i according to the water withdrawal amount of pollution source i and the nitrogen and phosphorus concentration in the water withdrawal of pollution source i.

[0144] In an optional embodiment, the water withdrawal determination unit is specifically used for: when the pollution source i is a dry field, obtaining the first precipitation, the first irrigation amount, the soil evaporation, the first crop transpiration, the groundwater recharge, the deep seepage, and the soil water storage change of the pollution source i; calculating the water withdrawal of the pollution source i according to the first precipitation, the first irrigation amount, the soil evaporation, the first crop transpiration, the groundwater recharge, the deep seepage and the soil water storage change; and / or; when the pollution source i is a paddy field, obtaining the second precipitation, the second irrigation amount, the field surface evaporation and the second crop transpiration of the pollution source i; calculating the water withdrawal of the pollution source i according to the second precipitation, the second irrigation amount, the field surface evaporation and the second crop transpiration.

[0145] In an optional embodiment, the migration path absorption capacity determination module 905 includes a pollutant reception ratio determination unit and an absorption capacity determination unit. The pollutant reception ratio determination unit is used to determine the proportion of upstream pollutants received by each intermediate water body according to the type of each intermediate water body; the absorption capacity determination unit is used to obtain the absorption capacity of each migration path according to the nitrogen and phosphorus loss of each pollution source, the migration path corresponding to each pollution source, and the proportion of upstream pollutants received by each intermediate water body.

[0146] In an optional embodiment, the unit for determining the proportion of received pollutants is used to obtain, when the intermediate water body is a linear water body, the number of linear water bodies in the migration path to which the intermediate water body belongs, the path length from the pollution source corresponding to the intermediate water body to the intermediate water body, the hydraulic radius from the pollution source corresponding to the intermediate water body to the intermediate water body, the slope from the pollution source corresponding to the intermediate water body to the intermediate water body, and the depth of the intermediate water body; calculate the proportion of upstream pollutants received by the intermediate water body based on the number of linear water bodies in the migration path to which the intermediate water body belongs, the path length, the hydraulic radius, the slope and the depth; and / or; when the intermediate water body is a planar water body, obtain the total area of ​​the planar water area of ​​the migration path to which the intermediate water body belongs; and calculate the proportion of upstream pollutants received by the intermediate water body based on the total area of ​​the planar water area.

[0147] In an optional embodiment, the absorption capacity determination unit is used to determine the pollution source m corresponding to the migration path n, and all intermediate water bodies between the pollution source m and the target water body in the migration path n; the absorption capacity of the migration path n is obtained by using the nitrogen and phosphorus loss of the pollution source m and the proportion of upstream pollutants received by all intermediate water bodies between the pollution source m and the target water body; all migration paths are traversed to obtain the absorption capacity of each migration path.

[0148] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0149] The construction device of the agricultural watershed non-point source pollution decision support system in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above-mentioned functions.

[0150] The embodiment of the present invention also provides a computer device having the above Fig.10 The construction device of the agricultural watershed non-point source pollution decision support system shown.

[0151] See also Fig.10 , Fig.10 is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Fig.10As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Fig.10 A processor 10 is taken as an example.

[0152] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0153] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiment.

[0154] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0155] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0156] The computer device also includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30 and the output device 40 may be connected via a bus or other means. Fig.10 The example of connecting through bus is taken in the following.

[0157] The input device 30 can receive input digital or character information, and generate key signal input related to the user settings and function control of the computer device, such as a touch screen, a keypad, a mouse, a track pad, a touch pad, an indicator bar, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 may include a display device, an auxiliary lighting device (e.g., an LED) and a tactile feedback device (e.g., a vibration motor), etc. The above-mentioned display device includes but is not limited to a liquid crystal display, a light emitting diode, a display and a plasma display. In some optional embodiments, the display device can be a touch screen.

[0158] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0159] A part of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the existence of the computer program instruction in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc., and accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium accessible to the computer.

[0160] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for constructing a decision support system for agricultural watershed non-point source pollution, characterized in that: include: Obtain all pollution sources that flow into the target water body and calculate the nitrogen and phosphorus losses of each of the pollution sources; Get digital elevation data; Determine the intermediate water body between each of the pollution sources and the target water body according to the digital elevation data, and obtain a migration path corresponding to each of the pollution sources; Determine the type of each intermediate water body respectively, and determine the absorption capacity of each migration path according to the type of each intermediate water body; Obtaining the load of the target water body according to the nitrogen and phosphorus loss of each pollution source and the absorption amount of the migration path corresponding to each pollution source; An agricultural watershed non-point source pollution decision support system is constructed according to the load of multiple target water bodies.

2. The method according to claim 1, characterized in that The calculation of nitrogen and phosphorus loss from each pollution source comprises: When the pollution source is a planting source, for each pollution source i, determine the type of the pollution source i; Determine the amount of water discharged from the pollution source i according to the type of the pollution source i; Calculate the nitrogen and phosphorus concentrations in the return water from the pollution source i; The nitrogen and phosphorus loss of the pollution source i is determined according to the amount of water discharged from the pollution source i and the nitrogen and phosphorus concentrations in the discharged water of the pollution source i.

3. The method according to claim 1, characterized in that Determining the amount of water withdrawal from the pollution source i according to the type of the pollution source i includes: When the pollution source i is a dry field, the first precipitation, the first irrigation, the soil evaporation, the first crop transpiration, the groundwater recharge, the deep seepage, and the soil water storage change of the pollution source i are obtained; Calculate the amount of water withdrawal from the pollution source i according to the first precipitation, the first irrigation amount, the soil evaporation, the first crop transpiration, the groundwater recharge, the deep seepage and the change in the soil water storage; and / or; When the pollution source i is a paddy field, the second precipitation, the second irrigation amount, the field surface evaporation amount and the second crop transpiration amount of the pollution source i are obtained; The amount of water withdrawn from the pollution source i is calculated according to the second precipitation amount, the second irrigation amount, the field surface evaporation amount and the second crop transpiration amount.

4. The method according to claim 1, characterized in that: The steps of respectively determining the type of each intermediate water body and determining the absorption capacity of each migration path according to the type of each intermediate water body include: Determining the proportion of upstream pollutants received by each of the intermediate water bodies according to the type of each of the intermediate water bodies; The absorption capacity of each migration path is obtained according to the nitrogen and phosphorus loss of each pollution source, the migration path corresponding to each pollution source, and the proportion of upstream pollutants received by each intermediate water body.

5. The method according to claim 4, characterized in that Determining the proportion of upstream pollutants received by each intermediate water body according to the type of each intermediate water body includes: When the intermediate water body is a linear water body, obtaining the number of the linear water bodies in the migration path to which the intermediate water body belongs, the path length from the pollution source corresponding to the intermediate water body to the intermediate water body, the hydraulic radius from the pollution source corresponding to the intermediate water body to the intermediate water body, the slope from the pollution source corresponding to the intermediate water body to the intermediate water body, and the depth of the intermediate water body; Calculate the proportion of upstream pollutants received by the intermediate water body according to the number of the linear water bodies in the migration path to which the intermediate water body belongs, the path length, the hydraulic radius, the slope and the depth; and / or; When the intermediate water body is a planar water body, obtaining the total area of ​​the planar water area of ​​the migration path to which the intermediate water body belongs; The proportion of upstream pollutants received by the intermediate water body is calculated based on the total area of ​​the surface water body.

6. A decision support system for agricultural watershed non-point source pollution, characterized in that: The agricultural watershed non-point source pollution decision support system is constructed by using the construction method of any one of claims 1 to 5.

7. A device for constructing a decision support system for agricultural watershed non-point source pollution, characterized in that: The device comprises: The first acquisition module is used to acquire all pollution sources flowing into the target water body; A nitrogen and phosphorus loss calculation module, used to calculate the nitrogen and phosphorus loss of each of the pollution sources; The second acquisition module acquires digital elevation data; A migration path determination module, used to determine the intermediate water body between each of the pollution sources and the target water body according to the digital elevation data, and obtain a migration path corresponding to each of the pollution sources; A migration path absorption capacity determination module, used to respectively determine the type of each intermediate water body, and determine the absorption capacity of each migration path according to the type of each intermediate water body; A load determination module, used to obtain the load of the target water body according to the nitrogen and phosphorus loss of each pollution source and the absorption amount of the migration path corresponding to each pollution source; The system construction module is used to construct an agricultural watershed non-point source pollution decision support system according to the load of multiple target water bodies.

8. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the method for constructing an agricultural watershed non-point source pollution decision support system according to any one of claims 1 to 6 by executing the computer instructions.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the method for constructing an agricultural watershed non-point source pollution decision support system according to any one of claims 1 to 6.

10. A computer program product, characterized in that It comprises computer instructions, and the computer instructions are used to enable a computer to execute the method for constructing an agricultural watershed non-point source pollution decision support system according to any one of claims 1 to 6.

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