A simulation estimation method, device and equipment for transporting pesticides from a river basin to the sea

Abstract

The present invention discloses a simulation estimation method, device and equipment for the transportation of pesticides from a watershed to the sea, and relates to the technical field of pesticide transport simulation. The present invention establishes a global watershed pesticide output model PEWS, introduces the loss coefficient of pesticides in soil and the river attenuation coefficient, and simultaneously adds the environmental factors of pesticides in soil to the runoff change function, the watershed area function and the pesticide reservoir change function. From the time dimension, the simulation of the annual pesticide flux is converted to the simulation of the daily pesticide flux. From the space dimension, the sub-basin is refined into more detailed areas, so that the model can accurately simulate the specific diffusion of pesticides in different areas and different time periods in the watershed from the perspective of time and space variability and under multivariate interaction, and obtain the changes in pesticide emissions under different scenarios, so as to better evaluate the impact of pesticides on the ecosystem and provide a basis for the formulation of environmental governance and environmental policies.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticide transport simulation, and in particular to a simulation estimation method, device and equipment for transporting pesticides from a river basin to the sea. Background Art

[0002] Due to the limitations of pesticide sampling in terrestrial environments, people still know little about the sources and sinks of pesticides on land and in rivers, as well as the amount of transfer from land to rivers and ultimately to the coast. Although models have been used to estimate the transport of nutrients and other chemicals, these models often fail to accurately reflect the specific behavior of pesticides and their impact on the marine environment. Therefore, exploring the distribution of pesticides on land and in rivers based on survey data will help to better balance the relationship between agricultural production and the ecological environment and achieve sustainable development goals.

[0003] At present, researchers use the CREAMS model to estimate the surface runoff losses of soil, plant nutrients and pesticides. However, the CREAMS model is mainly applicable to small watersheds, requires a large number of parameters, is complex to operate, has low temporal resolution and lacks updates, which limits its application in large-scale and complex environments. When agricultural activities were gradually identified as the main source of non-point source pollution, researchers began to use the AGNPS model, SWRRB model, HSPF model and SWAT model. The AGNPS and SWRRB models are mainly applicable to small watersheds and single event simulations, and it is difficult to fully reflect the long-term processes of large-scale watersheds. Although the HSPF model can process continuous time series data, its parameter complexity and high computational requirements make it difficult to use in practical applications. The SWAT model performs well in simulating hydrological processes, but it requires a large number of measured parameters, which increases the difficulty of model construction and verification.

[0004] However, the models currently used are often suitable for simulating small watersheds and single events, and are difficult to process data in the continuous time domain; therefore, it is difficult to simulate the conversion process for large-scale and multi-variable environments, making it difficult to accurately simulate the migration and transformation of pesticides in different environmental media. Summary of the invention

[0005] The embodiments of the present invention provide a method, device and equipment for simulating and estimating the transportation of pesticides from a river basin to the sea, which can solve the problem in the prior art that it is difficult to accurately simulate the migration and transformation process of pesticides in different environmental media.

[0006] The embodiment of the present invention provides a simulation estimation method for the transport of pesticides from a river basin to the sea, comprising the following steps:

[0007] Obtain parameters related to the environment and pesticide use in the study area;

[0008] Construct the global basin pesticide export model PEWS; add environmental factors including temperature and pesticide degradation rate in the river to the runoff change function, basin area function and pesticide reservoir change function in the global basin pesticide export model PEWS, and obtain the pesticide transport function, pesticide river action function and improved pesticide reservoir change function respectively;

[0009] In the global basin pesticide export model PEWS, the migration amount of pesticides on land is obtained based on the parameters related to the environment and pesticide use; the input amount of pesticides transported from soil to rivers is obtained using the pesticide transport function and the migration amount; the pesticide river action function and the improved pesticide reservoir change function are used, and based on the input amount, the removal rate of pesticides in rivers, the deposition rate of pesticides in reservoirs and the proportion of pesticides discharged into rivers during the river transport process are obtained;

[0010] Based on the removal rate of pesticides in rivers, the deposition rate of pesticides in reservoirs and the proportion of pesticide discharge into rivers, the discharge of pesticides from rivers to the ocean was obtained.

[0011] Preferably, the method of obtaining the removal rate of pesticides in the river, the deposition rate of pesticides in the reservoir and the river discharge ratio of pesticides during the river transportation process includes:

[0012] The environmental and pesticide use related parameters in the study area include soil coverage, temperature, rainfall, water system distribution and pesticide use parameters;

[0013] Soil coverage, temperature, rainfall, water system distribution and pesticide use parameters were input into the global watershed pesticide export model PEWS. The global watershed pesticide export model PEWS was used to simulate the migration of pesticides on land in the study area to obtain the migration amount of pesticides on land.

[0014] The pesticide transport function and the migration amount of pesticides on land are used to simulate the migration of pesticides from land to rivers in the sub-basin, and the input amount of pesticides transported from soil to rivers is obtained;

[0015] The pesticide river action function and the input amount of pesticide transported to the river are used to simulate the degradation of pesticides in the river and obtain the removal rate of pesticides in the river.

[0016] The improved pesticide reservoir variation function and the input amount of pesticide transported to the river are used to simulate the retention of pesticides in the reservoir and obtain the deposition rate of pesticides in the reservoir.

[0017] The global watershed pesticide export model PEWS was used to simulate the discharge loss of pesticides in rivers and obtain the river discharge ratio of pesticides.

[0018] Preferably, the migration amount of the pesticide on land is obtained by the equation:

[0019] ;

[0020] in: Indicates the rate at which the pesticide dissipates in the plant; Indicates the duration from the initial measurement of pesticides.

[0021] Preferably, the input amount of the pesticide transported from the soil to the river is obtained by the equation:

[0022] ;

[0023] ;

[0024] ;

[0025] in: represents runoff; and is the fitting coefficient, which represents the removal rate constant of pesticides at different temperatures; a represents the runoff regulation coefficient; represents the temperature of basin j in month i; represents the annual average temperature of basin j; represents the soil microbial temperature coefficient; represents the average rainfall depth in month i; represents the retention parameter; Indicates the curve number for a certain month.

[0026] Preferably, obtaining the removal rate of the pesticide in the river includes:

[0027] Pesticides in rivers are subject to the interaction of degradation, adsorption, deposition, volatilization, bioaccumulation and transfer with water flow. The removal rate of pesticides in rivers is:

[0028] ;

[0029] in: represents the watershed area; represents the fitting coefficient, and The value of is obtained by fitting the half-life of pesticides at different temperatures; represents the temperature of basin j in month i; represents the annual mean temperature of basin j.

[0030] Preferably, the acquisition of the deposition rate of the pesticide in the reservoir includes:

[0031] The dam increases the water retention time and removes the pesticides. The dam is also affected by the temperature and flow rate of the reservoir. The deposition rate of pesticides in the reservoir is:

[0032] ;

[0033] Where: n represents the total number of reservoirs; It indicates the deposition rate of pesticides in the reservoir; Indicates the depth of the reservoir; Indicates water residence time; Indicates the reservoir number in the basin; It represents the total reservoir capacity of the basin; It indicates the effective storage capacity of the reservoir; represents the temperature of basin j in month i; represents the annual average temperature of basin j; b represents the reservoir regulation factor; and represents the reservoir rate constant.

[0034] Preferably, the formula for obtaining the river discharge ratio of the pesticide is:

[0035] ;

[0036] in: represents the discharge of river j before large-scale irrigation and other water withdrawal schemes were implemented in month i; represents the discharge of river j at the estuary after the implementation of the plan in month i.

[0037] Preferably, the pesticide discharge amount output from the river to the ocean is obtained by the equation:

[0038] ;

[0039] in: It indicates the removal rate of pesticides in rivers; It indicates the deposition rate of pesticides in the reservoir; Represents the proportion of river discharge of pesticides.

[0040] The embodiment of the present invention further provides a simulation estimation device for the transport of pesticides from a river basin to the sea, comprising:

[0041] Data module, used to obtain parameters related to environment and pesticide use in the study area;

[0042] The model module is used to construct the global basin pesticide export model PEWS; the environmental factors including temperature and pesticide degradation rate in the river are added to the runoff change function, basin area function and pesticide reservoir change function in the global basin pesticide export model PEWS, respectively, to obtain the pesticide transport function, pesticide river action function and improved pesticide reservoir change function;

[0043] The simulation module is used to obtain the migration amount of pesticides on land based on the parameters related to the environment and pesticide use in the global watershed pesticide export model PEWS; obtain the input amount of pesticides transported from soil to rivers using the pesticide transport function and migration amount; use the pesticide river action function and the improved pesticide reservoir change function, and obtain the removal rate of pesticides in rivers, the deposition rate of pesticides in reservoirs and the proportion of pesticides discharged into rivers during the river transport process based on the input amount;

[0044] Based on the removal rate of pesticides in rivers, the deposition rate of pesticides in reservoirs and the proportion of pesticide discharge into rivers, the discharge of pesticides from rivers to the ocean was obtained.

[0045] An embodiment of the present invention further provides an electronic device, including a memory and a processor;

[0046] The memory is used to store computer programs;

[0047] The processor is used to implement the steps of the simulation estimation method for the transportation of pesticides from a river basin to the sea when executing the computer program stored in the memory.

[0048] The embodiment of the present invention provides a simulation estimation method, device and equipment for the transportation of pesticides from a river basin to the sea. Compared with the prior art, the beneficial effects thereof are as follows:

[0049] The present invention introduces the loss coefficient of pesticides in soil and the river attenuation coefficient into the global basin pesticide output model PEWS, and simultaneously adds the environmental factors of pesticides in soil into the runoff change function, the basin area function and the pesticide reservoir change function. The environmental factors include temperature and the degradation rate of pesticides in the river, so as to form a pesticide transport function, a pesticide river action function and an improved pesticide reservoir change function. The improved function connects the simulations of various losses of pesticides in the pesticide transport process, solves the defects of the current single event simulation and continuous simulation process, and converts the simulation state from the simulation of the annual flux of pesticides to the simulation of the daily flux of pesticides, and at the same time refines the loss of pesticides in river flow into the loss in the river sub-basin. As a whole, the specific diffusion of pesticides in different regional environments and different time periods in the river basin is accurately simulated from the spatial dimension and the temporal dimension, so as to obtain the changes in the discharge of pesticides from the basin to the sea under different scenarios, so as to better evaluate the impact of pesticides on the ecosystem and provide a basis for the formulation of environmental governance and environmental policies. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A schematic diagram of the overall process of a simulation estimation method for transporting pesticides from a river basin to the sea provided by an embodiment of the present invention;

[0051] Figure 2 A schematic diagram of the pesticide transport process simulated by an improved PEWS model of a simulation estimation method for the transport of pesticides from a river basin to the sea provided in an embodiment of the present invention;

[0052] Figure 3 A schematic diagram of the monthly transport flux of atrazine from the surrounding area of ​​Laizhou Bay to the coast in a simulation estimation method of the transport of pesticides from a river basin to the sea provided in an embodiment of the present invention;

[0053] Figure 4 A schematic diagram of the monthly transport flux of nicosulfuron when the pesticide is transported from the surrounding area of ​​Laizhou Bay to the coast according to a simulation estimation method of the transport of pesticides from a river basin to the sea provided by an embodiment of the present invention;

[0054] Figure 5 A schematic diagram of monthly transport flux of chlorpyrifos when the pesticide is transported from the surrounding area of ​​Laizhou Bay to the coast according to a simulation estimation method of the transport of pesticides from a river basin to the sea provided by an embodiment of the present invention;

[0055] Figure 6 A schematic diagram of the monthly transport flux of imidacloprid from the surrounding area of ​​Laizhou Bay to the coast, according to a simulation estimation method for the transport of pesticides from a river basin to the sea provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0057] See also Figure 1 The embodiment of the present invention provides a simulation estimation method for the transport of pesticides from a river basin to the sea, comprising the following steps:

[0058] Step 1: Data collection and preprocessing.

[0059] Digital elevation data (DEM) (30m×30m) are from the Global Land Cover Database of the University of Maryland, USA; land use data are from the Resources and Environmental Science Data Center of the Chinese Academy of Sciences (https: / / www.resdc.cn / ); soil data are from the World Soil Database constructed by the Food and Agriculture Organization of the United Nations (FAO) and the International Institute for Applied Systems Research (IIASA) in Vienna; the temperature and rainfall data designed in this paper are from the National Bureau of Statistics; the spatial distribution data of the three major grain crops are from the National Ecological Science Data Center (https: / / doi.org / 10.12199 / nesdc.ecodb.rs.2022.016); the reservoir geospatial database is from the Scientific Database (https: / / www.scidb.cn / s / zqIFVr); the water system in the study area is vectorized based on the SRTMDEM 90M resolution original elevation data, and corrected with the fourth and fifth level rivers of the national basic geographic information data. The upstream and downstream relationships and confluence networks of the sub-basins are determined based on the Vörösmarty CJ et al. established the topological structure between sub-basins; based on the new pollutant voyage of typical offshore bays through two land-sea synchronous survey data in 2022.8 and 2023.5 as verification; found that atrazine ( ) and Nicosulfuron ( ) Mixed herbicides are mainly used for corn, targeting annual grass weeds and broadleaf weeds, such as foxtail grass and purslane; imidacloprid ( ) is mainly applied to food crops, vegetables and fruit trees; chlorpyrifos ( ) are mainly applied on grain crops; the pesticide use data of atrazine, nicosulfuron, chlorpyrifos and imidacloprid are obtained from actual on-land surveys. Based on farmers following the recommended dosage on the pesticide bottles, the usage intensity of atrazine, nicosulfuron, chlorpyrifos and imidacloprid is shown in Table 1.

[0060] Table 1 Physical and chemical properties of four typical pesticides

[0061]

[0062] Step 2: Model construction.

[0063] The Pesticides Export from Watersheds to Sea (PEWS) model is used to calculate pesticide fluxes and introduces parameters such as the loss coefficient of pesticides in soil and the river attenuation coefficient. Although the SWAT model is used to simulate the dynamics of pesticides in soil and water resources, it does not take into account the complexity of the nature of pesticides and the need for a large amount of input data and parameter settings. In addition, improvements have been made in the time and space dimensions. Traditional models mainly calculate annual and monthly fluxes, while the PEWS model can calculate daily pesticide fluxes, thereby providing more detailed and dynamic pollutant transport data. In the spatial dimension, the division into sub-basins is combined with smaller areas to finely calculate the daily flux of pesticides from land to the estuary in smaller areas. This improvement in spatial resolution enables the model to more accurately reflect the pollution situation in local areas, help identify specific pollution sources, and provide more targeted governance solutions. Therefore, using it to calculate pesticide fluxes to improve the model's simulation accuracy of pesticide loss behavior can provide a more comprehensive consideration for environmental monitoring and better evaluate the impact of pesticides on ecosystems.

[0064] Step 3: Pesticide flux calculation.

[0065] The Pesticides Export from Watersheds to Sea (PEWS) model was used to calculate the flux of pesticides from rivers to estuaries in combination with the collected data.

[0066] Step 4: Environmental impact assessment.

[0067] Based on the pesticide flux results, the potential impacts of pesticides on downstream river and marine ecosystems were assessed.

[0068] Specifically:

[0069] The transport process of pesticides in the Pesticides Export from Watersheds to Sea (PEWS) model ( Figure 2 ) The simulation can be divided into 3 steps, including:

[0070] Step 1: Quantify the transport of pesticides on land.

[0071] Step 2: Quantifying pesticide inputs from land to sub-catchment rivers, pesticide retention and losses in soils were considered as a function of air temperature and runoff from land to rivers.

[0072] Step 3: Pesticides exported from each sub-basin were quantified by source and season, and retention and losses of pesticides in rivers were considered as a function of pesticide degradation, reservoir sedimentation, and water consumption.

[0073] In the model, the pesticide output from the jth river to coastal waters in month i ( , )for:

[0074] .

[0075] in: represents the pesticide output from the jth river to the coastal waters in month i-1 ( ); represents the amount of pesticide applied in month i ( ); represents the fraction of pesticides that reached the soil surface after being washed off plant leaves in month i (0-1); represents the fraction (0-1) of pesticides from land transported from soil to rivers; A fraction (0-1) representing the export of pesticides from rivers to marine systems.

[0076] Among them The calculation formula is:

[0077]

[0078] in: Indicates the amount of pesticide applied per unit area ( ), Represents the crop area ( ).

[0079] In the detailed calculation of the model, the calculation process of pesticide flux is mainly the amount of pesticides transmitted from farmland to downstream or ocean through rainwater scouring of plant leaves, soil infiltration, river transportation and other media. First, the amount of pesticides entering the river each month is calculated based on the amount of pesticides applied and the interception, loss and reduction ratio of vegetation, soil and rivers in different links. Subsequently, the output of pesticides in the current month is accumulated by the output of pesticides in the previous month, and then the additional output of pesticides in this month after each process is added to calculate the total flux of pesticides transported from land to rivers.

[0080] ① In the first step of pesticide migration on land, the degradation of some pesticides is determined by the properties of the pesticides themselves and is related to the half-life of pesticide dissipation from plants, among which the plant half-life is affected by comprehensive factors such as material properties, plant properties, temperature and research conditions; another part of the pesticide residues on crops will be washed away when encountering precipitation, in which the pesticides are washed into surface water bodies by rain or enter deep soil with the infiltration of water; is to quantify the migration of pesticides on land. is defined as:

[0081] .

[0082] in: It represents the rate of pesticide dissipation in plants (1 / d). The values ​​of different pesticides are shown in Table 2. Indicates the time (d) from the initial amount of pesticide determination.

[0083] Table 2 Half-life and rate of pesticide dissipation in plants

[0084]

[0085] ② In the second step, pesticide inputs from land to sub-basin rivers were quantified. Pesticide retention and losses in soil were considered as a function of air temperature and runoff from land to rivers. represents the fraction of terrestrial-derived pesticides transported from soil to rivers; is defined as:

[0086] .

[0087] .

[0088] .

[0089] in: represents runoff ( ); and is the fitting coefficient, which represents the removal rate constant (1 / d) of pesticides at different temperatures. In the present invention, and The value of is obtained by fitting the half-life of pesticides at different temperatures, as shown in Table 3; a represents the runoff regulation coefficient; represents the temperature of basin j in month i (℃); represents the annual average temperature of basin j (°C); represents the soil microbial temperature coefficient, which represents the change rate of pesticide degradation in soil for every 10°C increase in air temperature; in the present invention, The values ​​of are shown in Table 3; represents the average rainfall depth in month i (mm); represents the retention parameter (mm); The curve number for a certain month is mainly determined by land use type, soil hydrology group, surface conditions and initial moisture conditions; The value of is between 0 and 1. In the migration of pesticides from soil to rivers, runoff has been found to be an important influencing factor in the transport of pesticides through soil, streams and small river basins. The above formula represents a function related to runoff, taking into account environmental factors of pesticides in soil, such as temperature and the degradation rate of pesticides in soil.

[0090] Table 3 Parameters of pesticides in soil

[0091]

[0092] ③ In the third step, the exported pesticides in each sub-basin were quantified by source and season. The retention and loss of pesticides in the river were considered to be affected by three factors: pesticide degradation in the river, reservoir deposition and water consumption; each process was expressed as a removal fraction (0-1). Finally, the amount of pesticide exported from the river to the marine system ( ) is the product of these components; is defined as:

[0093] .

[0094] in: It indicates the removal rate of pesticides in rivers; It indicates the pesticide retention in the reservoirs within the river basin; Indicates the consumption of water removal fraction.

[0095] It is the removal rate of pesticides in rivers. Pesticides in rivers are subject to the interaction of degradation, adsorption deposition, volatilization, bioaccumulation and transfer with water flow. The quantification is as follows:

[0096] .

[0097] in: represents the watershed area ( ); represents the fitting coefficient, and is fitted according to the degradation rate constant of pesticides in rivers at different temperatures (1 / d); in the present invention, and The value of is obtained by fitting the half-life of pesticides at different temperatures (as shown in Table 4); represents the temperature of basin j in month i (℃); represents the annual average temperature of basin j (℃); such as temperature and degradation rate of pesticides in rivers; the above formula represents a fitting curve related to the basin area, which includes environmental factors of pesticides in rivers, such as temperature and degradation rate of pesticides in rivers.

[0098] Table 4 Parameters of pesticides in rivers

[0099]

[0100] is the pesticide retention in reservoirs within a river basin. Reservoirs can have a profound impact on the transport of biogeochemical components by rivers. Water retention behind dams increases the residence time of water, so there is an opportunity for removal processes, where the process of pesticides in reservoirs is affected by factors such as temperature and flow rate. The improved formula is:

[0101] .

[0102] Where: n represents the total number of reservoirs; Weighted by the proportion of the total basin flow intercepted by the reservoir; Reservoir depth ( ); Indicates water residence time (years); Indicates the reservoir number in the basin; the retention capacity of each reservoir in the basin is aggregated into the basin average through the weighted arithmetic mean of the reservoir retention capacity; represents the total reservoir capacity of the basin ( ); Represents the effective storage capacity of the reservoir ( ); represents the temperature of basin j in month i (℃); represents the annual average temperature of basin j (°C); b represents the reservoir regulation factor; and represents the reservoir rate constant, and its value is based on the degradation rate in the river, as shown in Table 4; the above formula is an improved formula, which adds environmental factors of pesticides in the reservoir, such as temperature and the degradation rate of pesticides in the river.

[0103] The proportion of river discharge that is consumptive removals. Water withdrawn from rivers for human irrigation, domestic and industrial use may be returned to the rivers or permanently consumed, mainly through evapotranspiration from irrigated land and inter-basin transfers; the proportion of river discharge that is consumptive removals is calculated from natural discharge to actual discharge and is:

[0104] .

[0105] in: represents the discharge of river j before large-scale irrigation and other water withdrawals were implemented in month i ( ); represents the discharge of river j at the estuary after the implementation of the plan in month i ( ).

[0106] Ultimately, pesticides are input from the outlet of the sub-basin with tributaries to the sub-basin with the main channel, which then exports pesticides to the estuary. During this export process, some pesticides may be lost or retained, for example, through degradation in the river, reservoir depletion, and water consumption; in general, the proportion of pesticides delivered from each sub-basin outlet to the estuary depends on the distance from the outlet to the estuary.

[0107] The MATLAB (R2022b, MathWorks) software platform was used to write the Pesticides Export from Watersheds to Sea (PEWS) model. The simulated values ​​were compared with the measured values, and the parameters were automatically optimized using Monte Carlo simulation. Based on the principle of minimizing the error, the recommended usage per unit area of ​​each pesticide was used to estimate the pesticide usage in each smaller area, and the model input parameters, runoff control coefficient a and reservoir control factor b, were determined. Finally, these parameters were substituted into the model to simulate the pesticide transport process on land, and the model was repeated 1000 times.

[0108] Data from two land-sea synchronous surveys in August 2022 and May 2023 were selected to verify the output of four typical pesticides in seasonal rivers at the outlets of the upper, middle and lower basins in the area around Laizhou Bay in summer and spring; the standardized efficiency coefficient (NSE) was used to evaluate the model performance to understand the degree of fit between the modeled data and the observed data; in the specific study, the model performance was defined as satisfactory or unsatisfactory, and marked according to the values ​​of the standardized efficiency coefficient (NSE) and the root mean square error (RMSE); specifically, when the NSE was greater than 0.50, the model performance was marked as satisfactory; conversely, when the NSE was less than 0.50, it was marked as unsatisfactory. The root mean square error (RMSE) reflects the ratio between the absolute error caused by the simulation results and the true value of the observation. A lower RMSE value indicates that the simulated value of the model is closer to the observed value and has a higher accuracy; there are:

[0109] .

[0110] .

[0111] in: represents the measured i-th observation value; represents the i-th simulation value of the model; represents the average value of the measured data; n represents the total number of observations.

[0112] Based on the crop planting and land use types in the basin, the input of different sub-basin units can be obtained by using the Pesticides Export from Watersheds to Sea (PEWS) model. According to the pollutant concentration and hydrological data, the total amount of pesticide pollutants discharged into Laizhou Bay in 2022 is estimated to be 6071.76 ,303.25 ,86.81 and 436.45 They are atrazine, nicotinamide, chlorpyrifos, and imidacloprid; Figure 3 The figure shows the monthly transport flux diagram when the pesticide is atrazine. Figure 4 The figure shows the monthly transport flux diagram when the pesticide is nicosulfuron. Figure 5 The figure shows the monthly transport flux when the pesticide is chlorpyrifos. Figure 6 Shown is a schematic diagram of monthly transport flux when the pesticide is imidacloprid.

[0113] The present invention simplifies the estimation of the loss of different forms of materials by using a global database and a more general algorithm to predict material output under different scenarios.

[0114] The general simple multiplication method (concentration × water flux) usually assumes that the concentration and water flux are constant during the calculation period, or can only roughly estimate their average values; the Pesticides Export from Watersheds to Sea (PEWS) model can take into account the variability in time and space and the interaction of multiple factors and processes, simulate the specific conditions in different areas and time periods in the basin, and provide a more dynamic and detailed analysis; and the traditional method can only be used for backward calculation of known data, but cannot perform predictive analysis of future scenarios; the Pesticides Export from Watersheds to Sea (PEWS) model can simulate based on different environmental and management scenarios, provide decision makers with predictions and assessments of future changes, and support policy making and resource management.

[0115] The present invention establishes the application field of pesticide flux calculation and introduces parameters such as the loss coefficient of pesticides in soil and the river attenuation coefficient; although the SWAT model is used to simulate the dynamics of pesticides in soil and water resources, it also has some shortcomings, and does not take into account the complexity of pesticide properties and the need for a large amount of input data and parameter settings. Therefore, establishing a calculation model for pesticide flux and introducing pesticide-related parameters is an innovative application of the model; thus, it can provide more comprehensive considerations for environmental monitoring and better evaluate the impact of pesticides on ecosystems.

[0116] From a temporal perspective, Pesticides Export from Watersheds to Sea (PEWS) is calculated based on daily data. This time scale does not mask the impact of seasonal changes and short-term events (such as floods or droughts), and can more accurately reflect the dynamic changes in pesticide usage and entry into water bodies in different seasons. The use and loss of pesticides often have obvious seasonal characteristics. For example, pesticide usage is usually higher in spring and summer, and changes in precipitation can affect the runoff and amount of pesticides entering the sea. Calculating flux on a daily basis can capture these seasonal changes, thereby providing more timely pollution forecasting and management information. Daily data can improve the model's sensitivity to short-term trends and the impact of extreme weather events, thereby improving the prediction accuracy of pollution events, taking timely response measures, and reducing damage to marine and freshwater ecosystems.

[0117] From a spatial dimension, refining the spatial scale of the model from sub-watersheds to smaller areas can more accurately locate the sources of pesticide use and pollution; this allows the model to reflect the use of pesticides on a smaller scale and their migration paths to water bodies; by combining regional data, the model can identify which areas are the main sources of pesticide pollution, thereby providing a scientific basis for formulating more targeted pesticide management and emission reduction policies; detailed regional analysis can more effectively allocate environmental monitoring and governance resources, concentrate efforts on solving serious pollution areas, and improve governance efficiency.

[0118] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A simulation estimation method for the transport of pesticides from a river basin to the sea, characterized in that: The following steps are involved: Obtain parameters related to the environment and pesticide use in the study area; Construct the global basin pesticide export model PEWS; add environmental factors including temperature and pesticide degradation rate in the river to the runoff change function, basin area function and pesticide reservoir change function in the global basin pesticide export model PEWS, and obtain the pesticide transport function, pesticide river action function and improved pesticide reservoir change function respectively; In the global basin pesticide export model PEWS, the migration amount of pesticides on land is obtained based on the parameters related to the environment and pesticide use; the pesticide transport function and the migration amount of pesticides on land are used to simulate the migration of pesticides from land to sub-basin rivers, and the input amount of pesticides transported from soil to rivers is obtained; the pesticide river action function and the input amount of pesticides transported to rivers are used to simulate the degradation of pesticides in rivers, and the removal rate of pesticides in rivers is obtained; the improved pesticide reservoir change function and the input amount of pesticides transported to rivers are used to simulate the retention of pesticides in reservoirs, and the deposition rate of pesticides in reservoirs is obtained; the global basin pesticide export model PEWS is used to simulate the discharge loss of pesticides in rivers, and the river discharge ratio of pesticides is obtained; Based on the removal rate of pesticides in rivers, the deposition rate of pesticides in reservoirs and the proportion of pesticide discharge into rivers, the discharge of pesticides from rivers to the ocean was obtained.

2. The simulation estimation method for the transport of pesticides from a river basin to the sea according to claim 1 is characterized in that: The method of obtaining the removal rate of pesticides in rivers, the deposition rate of pesticides in reservoirs and the proportion of pesticide discharge into rivers during the transportation of pesticides in rivers includes: The environmental and pesticide use related parameters in the study area include soil coverage, temperature, rainfall, water system distribution and pesticide use parameters; The soil coverage, temperature, rainfall, water system distribution and pesticide use parameters were input into the global watershed pesticide export model PEWS. The global watershed pesticide export model PEWS was used to simulate the migration of pesticides on land in the study area to obtain the migration amount of pesticides on land.

3. The simulation estimation method for the transport of pesticides from a river basin to the sea according to claim 2 is characterized in that: The equation for obtaining the migration amount of the pesticide on land is: FE i =exp(-k i ·Δt); Where: k i It indicates the rate at which the pesticide dissipates in the plant; Δt indicates the time elapsed from the initial measurement of the pesticide.

4. The simulation estimation method for the transport of pesticides from a river basin to the sea according to claim 1 is characterized in that: The formula for obtaining the input amount of the pesticide from the soil to the river is: FE soil,i =μ soil,1 ×Runoff i a ×exp(-μ soil,2 ·Q 10，soil ·(T i,j -T ave,j ) / 10); Where: Runoff i represents runoff; μ soil,1 and μ soil,2 is the fitting coefficient, which represents the removal rate constant of pesticides at different temperatures; a represents the runoff regulation coefficient; T i,j represents the temperature of basin j in month i; T ave,j represents the annual average temperature of basin j; Q 10，soil Represents soil microbial temperature coefficient; Rain i represents the average rainfall depth in the ith month; S represents the retention parameter; CN represents the curve number of a certain month.

5. The simulation estimation method for the transport of pesticides from a river basin to the sea according to claim 1 is characterized in that: The removal rate of the pesticide in the river is obtained, including: Pesticides in rivers are subject to the interaction of degradation, adsorption, deposition, volatilization, bioaccumulation and transfer with water flow. The removal rate of pesticides in rivers is: L i,j =μ river,i,j,1 ·ln(A)·exp(μ river,i,j,2 ·(T i,j -T ave,j ) / 10); Where: A represents the basin area; μ river,i,j represents the fitting coefficient, μ river,i,j,1 and μ river,i,j,2 The value of is obtained by fitting the half-life of pesticides at different temperatures; T i,j represents the temperature of basin j in month i; T ave,j represents the annual mean temperature of basin j.

6. The simulation estimation method for the transport of pesticides from a river basin to the sea according to claim 1 is characterized in that: The acquisition of the deposition rate of the pesticide in the reservoir includes: The dam increases the water retention time and removes the pesticides. The dam is also affected by the temperature and flow rate of the reservoir. The deposition rate of pesticides in the reservoir is: Where: n represents the total number of reservoirs; D i,j Indicates the deposition rate of pesticides in the reservoir; DEPT t Indicates the reservoir depth; Rt t represents the water residence time; t represents the reservoir number in the basin; Q j represents the total reservoir capacity of the basin; Q t Represents the effective storage capacity of the reservoir; T i,j represents the temperature of basin j in month i; T ave,j represents the annual average temperature of basin j; b represents the reservoir regulation factor; μ dam,i,j,1 and μ dam,i,j,2 represents the reservoir rate constant.

7. The simulation estimation method for the transport of pesticides from a river basin to the sea according to claim 1 is characterized in that: The equation for obtaining the proportion of the pesticide discharge into rivers is: Again i,j =(Q nat,i,j -Q act,i,j ) / Q nat,i,j ; Where: Q nat,i,j Q is the discharge of river j before large-scale irrigation and other water withdrawals are implemented in month i; act,i,j represents the discharge of river j at the estuary after the implementation of the plan in month i.

8. The simulation estimation method for the transport of pesticides from a river basin to the sea according to claim 1 is characterized in that: The equation for obtaining the pesticide discharge from the river to the ocean is: <h2 style=";text-align:left;direction:ltr">FE<h2 style=";text-align:left;direction:ltr"> riv,i,j <h2 style=";text-align:left;direction:ltr"> (1-L)<h2 style=";text-align:left;direction:ltr"> i,j <h2 style=";text-align:left;direction:ltr"> )·(1-D<h2 style=";text-align:left;direction:ltr"> i,j <h2 style=";text-align:left;direction:ltr"> )·(1-FQrem<h2 style=";text-align:left;direction:ltr"> i,j <h2 style=";text-align:left;direction:ltr"> ); Where: L i,j Indicates the removal rate of pesticides in rivers; D i,j Indicates the deposition rate of pesticides in the reservoir; FQrem i,j Represents the proportion of river discharge of pesticides.

9. A simulation and estimation device for the transport of pesticides from a river basin to the sea, characterized in that: include: Data module, used to obtain parameters related to environment and pesticide use in the study area; Model module, used to build the global watershed pesticide export model PEWS; Environmental factors including temperature and degradation rate of pesticides in rivers were added to the runoff change function, basin area function and pesticide reservoir change function in the global basin pesticide export model PEWS, thus obtaining the pesticide transport function, pesticide river action function and improved pesticide reservoir change function respectively. The simulation module is used to obtain the migration amount of pesticides on land based on the parameters related to the environment and pesticide use in the global basin pesticide export model PEWS; use the pesticide transport function and the migration amount of pesticides on land to simulate the migration of pesticides from land to sub-basin rivers, and obtain the input amount of pesticides transported from soil to rivers; use the pesticide river action function and the input amount of pesticides transported to rivers to simulate the degradation of pesticides in rivers and obtain the removal rate of pesticides in rivers; use the improved pesticide reservoir change function and the input amount of pesticides transported to rivers to simulate the retention of pesticides in reservoirs and obtain the deposition rate of pesticides in reservoirs; use the global basin pesticide export model PEWS to simulate the discharge loss of pesticides in rivers and obtain the river discharge ratio of pesticides; Based on the removal rate of pesticides in rivers, the deposition rate of pesticides in reservoirs and the proportion of pesticide discharge into rivers, the discharge of pesticides from rivers to the ocean was obtained.

10. An electronic device, characterized in that: include: Memory and processor; The memory is used to store computer programs; The processor is used to implement the steps of a method for simulating and estimating the transport of pesticides from a river basin to the sea as described in any one of claims 1 to 8 when executing the computer program stored in the memory.

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