A dynamic calculation method for sediment trapping capacity of siltation dam at basin scale

Abstract

The present application relates to the technical field of water and soil conservation, and provides a dynamic calculation method for the sand blocking capacity of a silt dam system at a watershed scale, wherein a spatially distributed water and sediment process model is constructed to obtain the water and sediment inflow of different sub-watersheds, which in turn drives a silt dam sediment blocking simulation module constructed by the present application to realize the spatio-temporal dynamic simulation of the sediment blocking of the silt dam system at the watershed scale. The calculation method provided by the present application not only provides effective support for the problem solving of the sediment reduction benefit estimation of the silt dam at the watershed scale and the Yellow River harnessing, but also provides algorithm support for the planning and design of the silt dam and the efficient utilization of water and soil resources.

Description

Technical Field

[0001] This invention relates to the field of soil and water conservation technology, specifically to a dynamic calculation method for the sediment retention capacity of silt-trapping dams at the watershed scale. Background Technology

[0002] Silt-retaining dams are widely used in ecological restoration and soil and water conservation in areas of global soil erosion, playing a vital role in controlling watershed soil erosion and reducing river sediment transport. Long-term construction and operation practices of silt-retaining dams in my country's Yellow River Basin have shown that silt-retaining dam systems composed of multiple dams typically possess a more stable and secure structure, exhibiting a more prominent advantage in water and sediment interception, especially during flood events. The planning and construction of silt-retaining dam systems in the middle reaches of the Yellow River have developed rapidly, significantly impacting water and sediment processes in the basin. The scientific simulation and rational quantification of the water and sediment effects of watershed silt-retaining dam systems is a key and challenging issue in regional water and sediment change research. The inversion of the dynamic process of sediment interception by silt-retaining dams is fundamental to studying sediment interception and its water and sediment effects, and is also related to the scientific prediction of available reservoir capacity for watershed silt-retaining dams and the comprehensive management of watershed dam systems.

[0003] Long-term research has developed various methods for inverting sediment retention by silt-retaining dams. These include the profile method (through excavation or borehole observation), the topographic method (based on comparison of pre- and post-siltation topography), and the resistivity method (directly measuring sediment volume). However, these methods suffer from drawbacks such as high time and economic costs, limited applicability at the watershed scale, and inability to reflect sediment deposition dynamics. Hydrological process models can effectively reflect the response of water and sediment transport to environmental changes; however, currently used hydrological models lack effective generalization and simulation of water and sediment processes at silt-retaining dams. Proposing a computational method to simulate the dynamic sediment retention capacity of silt-retaining dam systems at the watershed scale would be a significant advancement in the quantitative analysis of the water and sediment reduction benefits of silt-retaining dams, providing a scientific basis for the scientific planning and deployment of watershed water and soil conservation measures, and playing a crucial role in solving flood and sediment problems and ensuring the safety of the Yellow River.

[0004] Therefore, this proposal specifically suggests a dynamic calculation method for the sediment retention capacity of silt-trapping dams at the watershed scale to address the aforementioned issues. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a dynamic calculation method for the sediment retention capacity of silt-trapping dams at the watershed scale.

[0006] To achieve the aforementioned objective, the technical solution of this invention is as follows: a calculation scheme for the dynamic sediment retention capacity of watershed silt-retaining dams, addressing the problems of high time and economic costs, difficulty in extending application to watershed scales, and unclear sediment retention benefits of silt-retaining dams in key soil and water conservation engineering measures, as well as the contribution of different dam systems to watershed sediment transport in current technologies. To achieve this objective, this invention develops a dynamic sediment retention module for watershed silt-retaining dam systems, combining it with a hydrological process model to establish a dam system sediment retention simulation framework (SWAT-DCDam), enabling dynamic tracking of sediment retention by watershed dam systems and providing the contribution of dam system sediment retention to watershed sediment transport and its dynamic changes. The specific technical methods are as follows:

[0007] (1) Building a watershed hydrological model (SWAT)

[0008] Collect and study watershed elevation, land use, soil, and climate-hydrological data, prepare model input databases, and build watershed hydrological models using ArcSWAT software.

[0009] The first step is to input watershed elevation data and perform watershed river network delineation, runoff generation and confluence calculation, and sub-watershed delineation, etc.

[0010] The second step involves inputting land use, soil, and slope information. Within the sub-basin, this information is reclassified and superimposed to divide the data into hydrological response units (HRUs). The underlying surface features of each HRU are consistent, serving as the smallest unit for hydrological calculation.

[0011] The third step is to load the station information index table of five meteorological elements—precipitation, temperature, wind speed, relative humidity, and solar radiation—into the meteorological module of the model, and then write all the input data from meteorological and soil databases into the model.

[0012] Finally, by setting the simulation start and end years, simulation step size, and warm-up period, and then clicking "Run," the SWAT model can be completed.

[0013] (2) Calibration and verification of the water and sediment process model

[0014] After the model is established, in order to ensure that the simulated watershed hydrological conditions are under natural conditions, the simulation results need to be calibrated and verified.

[0015] The first step is to collect and organize runoff and sediment observation data during the simulation period, and to determine the rate-setting period and the validation period;

[0016] The second step is to select and adjust the parameters for runoff and sediment based on previous research experience and relevant measured data in the study area.

[0017] The third step is to determine the parameter calibration method. Using SWAT-CUP software, the optimization of model parameters begins by inputting observation data, setting parameter ranges, inputting the number of iterations, and saving the data.

[0018] Finally, based on the coefficient of determination (R²) 2 Evaluation metrics such as Nash coefficient (NSE) and percentage bias (PBIAS) are used to assess model performance, with R... 2 The standard for judging whether the simulation results are satisfactory is that NSE > 0.5 and |PBIAS| ≤ 30%, and the optimal parameters are finally determined.

[0019] (3) Mathematical generalization of the water and sediment interception process of silt-retaining dams

[0020] Assuming the runoff flowing into the dam has a uniform sediment content, its volumetric sediment content is C. con,t The sediment content of the discharged runoff is equal to the sediment content of the incoming water. Therefore, the relationship between the increase in siltation by the silt-retaining dam per unit step length at time t and the change in available reservoir capacity is shown in formulas (1) and (2):

[0021] V D,t =V D,t-1 -V Sr ,t (1)

[0022] V Sr ,t =V Si ,t -V So ,t (2)

[0023] In the formula: V D , t Let m be the available reservoir capacity of the silt-retention dam at time t. 3 V Sr ,t Let m be the volume of newly intercepted sediment by the silt-retaining dam within a unit time step at time t. 3 V Si ,t Let m be the volume of sediment entering the silt-retaining dam per unit time step at time t. 3 V So , t Let be the volume of sediment discharged with runoff per unit time step at time t, in meters. 3 .

[0024] ① If the silt-retention dam is an end dam, the controlled area of ​​the silt-retention dam (A) d Then, the actual controlled area (A) at time t is... a , t ).

[0025] When the available reservoir capacity V of the silt-retention dam D ,t-1 Water inflow V greater than or equal to the unit time Wi ,t At that time, the upstream inflow (calculated based on the runoff depth) and sediment (calculated based on the sediment content C) con,t The calculated runoff (V) is completely intercepted by the silt-retaining dam. Wo , t The value is 0. Wi ,t and V Si ,t It can be calculated using formulas (3) to (5):

[0026] V wi ,t =A d ×H t (3)

[0027] V Sr ,t =V Si ,t (4)

[0028] V Si ,t =V Wi ,t ×C con ,t (5)

[0029] When the silt-retention dam has a usable reservoir capacity V D,t-1 Water volume V less than the unit time Wi ,t At that time, the silt-retention dam can use its entire available reservoir capacity for water storage, partially intercepting upstream water flow and discharging a runoff of V. Wo ,t The corresponding volume of discharged sediment is V. So ,t V Wo ,t V Sr ,t and V So, t The calculation is as shown in formulas (6) to (8):

[0030] V wo ,t =V Wi ,t -V D,t-1 (6)

[0031] V Sr ,t =V Dt-1 ×C con ,t (7)

[0032] V So ,t =V Wo ,t ×C con ,t (8)

[0033] ② If the silt-retention dam is not the terminal dam, the runoff mainly comes from the discharge of the upstream silt-retention dam and the inflow of water from the actual controlled area.

[0034] Suppose there are p silt-retaining dams directly connected to it and located upstream of it, then the total water (V) upstream of this non-terminal dam... Wi , t ) and actual dam-controlled area (V a ,t The calculations are as shown in formulas (9) to (10):

[0035]

[0036] After obtaining the upstream water flow from the non-terminal silt-retaining dams, the actual runoff and sediment interception and discharge of each silt-retaining dam can be calculated based on the calculation method for the actual sediment interception of the terminal silt-retaining dams.

[0037] (4) Data Interaction and Computational Simulation

[0038] The DCDam module uses the simulation step size of the SWAT model, takes the runoff and sediment output by the model as the driving data, and takes the sub-basin as the basic calculation unit. Based on the simulation results of water and sediment transport in each sub-basin, it superimposes the siltation dam system network of the sub-basin to calculate the sediment balance within the dam system.

[0039] The first step is to determine whether there is a silt-retaining dam system in the sub-basin. If there is no silt-retaining dam system in the sub-basin, the hydrological elements of the basin are calculated directly and the SWAT simulation results are output. If there is a silt-retaining dam system in the sub-basin, the silt-retaining dam variables are read and the upstream and downstream connection relationships of the silt-retaining dam system are generated.

[0040] The second step involves calculating from the terminal silt-collecting dam to lower-level silt-collecting dams at a single time t, until the calculations for all levels of silt-collecting dams are completed. After calculating the newly added siltation reservoir volume for all silt-collecting dams, the siltation status of the dams is updated, and then the calculation for the next time point begins, until the entire simulation process is completed. The specific data interaction process is as follows: Figure 2 .

[0041] (5) Spatiotemporal data extraction and spatial visualization of sediment interception by watershed-scale silt-retaining dam systems

[0042] Based on the data interaction framework developed using S4, dynamic simulations of sediment interception capacity of silt-retaining dams at the watershed scale are performed. The simulation results are extracted to present the spatiotemporal dynamics of sediment interception by silt-retaining dam systems at the watershed scale. Using spatiotemporal analysis methods of geospatial data, spatiotemporal visualization and analysis of sediment interception capacity are conducted for both sub-watersheds and individual silt-retaining dams.

[0043] The beneficial effects of this invention are reflected in:

[0044] Traditional methods for calculating the sediment retention capacity of silt-trapping dams suffer from high time and economic costs, difficulty in applying them to watershed scales, and an inability to reflect dynamic sediment characteristics. Furthermore, sediment process simulations based on hydrological models are incomplete in characterizing key soil and water conservation measures, failing to meet the practical needs of "digital" watershed management. Therefore, this invention develops a dynamic sediment retention simulation module for silt-trapping dam systems (DCDam). This module is combined with the widely used watershed water and sediment process model SWAT to achieve dynamic simulation of sediment interception by silt-trapping dams and to track sediment deposition and available reservoir capacity. This method features accurate and reasonable calculation of dam system sediment retention capacity and high computational efficiency. Developing this dynamic sediment retention capacity calculation method for silt-trapping dams provides an important tool for evaluating the benefits of watershed soil and water conservation. Attached Figure Description

[0045] In the attached diagram:

[0046] Figure 1 Design and calculation process for sediment retention modules of silt-retaining dams;

[0047] Figure 2Diagram of data interaction technology solution;

[0048] Figure 3 Comparison of simulation results of sediment retention capacity of silt-retaining dams in the case watershed;

[0049] Figure 4 This study examines the long-term dynamics of sediment retention by silt-trapping dams in the case study watershed.

[0050] Figure 5 This section illustrates the spatial distribution of sediment retention and reservoir capacity within the case study watershed's silt-retaining dam system. Detailed Implementation

[0051] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the invention, and not all of them. Unless otherwise specified, the embodiments and features described in this application can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0052] It should be noted that if the embodiments of the invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0053] Furthermore, "multiple" refers to two or more. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the invention.

[0054] This invention provides a method for calculating the dynamic sediment retention capacity of watershed silt-trapping dam systems, addressing the shortcomings of existing technologies, such as limited economic viability for watershed-scale application and inability to reflect sediment deposition dynamics. The following description and accompanying figures fully illustrate specific embodiments of this invention to enable researchers and managers in the field to effectively understand and implement it. (Refer to...) Figure 1 The technical roadmap is used to study the Yanhe River Basin as an example. The framework is applied to conduct dynamic simulation of sediment interception by silt-retaining dams. The specific implementation process is as follows:

[0055] (1) Constructing the SWAT hydrological model for the Yanhe River Basin

[0056] Collect elevation, land use, soil, and climate and hydrological data for the Yanhe River basin, prepare the model for input into the database, and begin building the model using ArcSWAT software.

[0057] The first step involves inputting watershed elevation data to perform river network delineation, runoff generation and concentration calculations, and sub-watershed division. These sub-watersheds are interconnected by river systems, resulting in a total of 202 sub-watersheds. Figure 3 The average area is 38.25 km². 2 ;

[0058] The second step involved inputting land use, soil, and slope information. Within the sub-basin, this information was reclassified and overlaid to create hydrological response units (HRUs). A total of 6053 HRUs were created, with an average area of ​​1.28 km². 2 ;

[0059] The third step is to load the station information index table of five meteorological elements—precipitation, temperature, wind speed, relative humidity, and solar radiation—into the meteorological module of the model, and then write all the input data from meteorological and soil databases into the model.

[0060] Finally, set the simulation start and end years to 1951 and 2020, the simulation step size to months, and the warm-up period to 5 years, then click Run to complete the construction of the Yanhe River Basin SWAT model.

[0061] (2) Model calibration and validation

[0062] After the model was established, in order to ensure that the simulated watershed hydrological conditions were in a natural state, the model was calibrated and validated before the implementation of large-scale soil and water conservation measures (1970).

[0063] The first step was to collect and organize the runoff and sediment observation data of the Yanhe River Basin during the simulation period, and select the hydrological data of Ganguyi Hydrological Station in the Yanhe River Basin as the observation data; the periods of 1957-1963 and 1964-1970 were set as the calibration period and the verification period, respectively, with the sediment calibration and verification based on the observation values ​​of the flood season from May to October.

[0064] The second step involves selecting nine parameters, including CN2, for runoff calibration based on research experience in the Loess Plateau region and relevant measured data. Additionally, three parameters, including USLE-C, are selected for sediment calibration. The selected parameters and their ranges are shown in Table 1.

[0065] The third step is to optimize the parameters using the SUFI-2 method of SWAT-CUP software. This involves periodically observing the data, setting the parameter range, inputting the number of iterations, and saving the data to begin optimizing the model parameters.

[0066] Finally, the coefficient of determination (R²) is selected. 2The model performance was evaluated using the Nash coefficient (NSE) and relative bias (PBIAS). The final simulation and observation fitting results are shown in Table 2. The runoff and sediment in both the rate-setting and validation periods met the R... 2 The results are considered good, with NSE > 0.5 and |PBIAS| ≤ 30%, indicating that the simulation effect is good and can be used for long-term simulation of abortion confluence and erosion sediment transport.

[0067] Table 1. Model parameter calibration results

[0068]

[0069] Note: In the table, "v" indicates that the new parameter replaces the default parameter, and "r" indicates that the parameter is adjusted according to a relative proportion based on the default parameter. For example, the calibration result of the SOL_K parameter is 0.052, which means that the calibrated parameter is (1+0.052) times the default parameter.

[0070] Table 2. Model performance during the periodic and validation phases.

[0071]

[0072] (3) Mathematical generalization of the water and sediment interception process of silt-retaining dams

[0073] Assuming the runoff flowing into the dam has a uniform sediment content, its volumetric sediment content is C. con,t The sediment content of the discharged runoff is equal to the sediment content of the incoming water. Therefore, the relationship between the increase in siltation of the silt-retaining dam per unit step length at time t and the change in available reservoir capacity is expressed by formulas (1) and (2).

[0074] ① If the silt-retention dam is an end dam, the controlled area of ​​the silt-retention dam (A) d Then, the actual controlled area (A) at time t is... a , t ).

[0075] When the available reservoir capacity V of the silt-retention dam D, t-1 Water inflow V greater than or equal to the unit time Wi , t At that time, the upstream inflow (calculated based on the runoff depth) and sediment (calculated based on the sediment content C) con , t The calculated runoff (V) is completely intercepted by the silt-retaining dam. Wo , t The value is 0. Wi ,t and V Si , t It can be calculated using formulas (3) to (5).

[0076] When the silt-retention dam has a usable reservoir capacity V D , t-1 Water volume V less than the unit time Wi , t At that time, the silt-retention dam can use its entire available reservoir capacity for water storage, partially intercepting upstream water flow and discharging a runoff of V. Wo ,t The corresponding volume of discharged sediment is V.So ,t V Wo ,t V Sr , t and V So ,t It is calculated by formulas (6) to (8).

[0077] ② If the silt-retention dam is not the terminal dam, the runoff mainly comes from the discharge of the upstream silt-retention dam and the inflow of water from the actual controlled area.

[0078] Suppose there are p silt-retaining dams directly connected to it and located upstream of it, then the total water (V) upstream of this non-terminal dam... Wi , t ) and actual dam-controlled area (V a , t The result is obtained by formulas (9) to (10).

[0079] After obtaining the upstream water flow from the non-terminal silt-retaining dams, the actual runoff and sediment interception and discharge of each silt-retaining dam can be calculated based on the calculation method for the actual sediment interception of the terminal silt-retaining dams.

[0080] (4) Data Interaction and Simulation Computation

[0081] Using the simulation step size of the SWAT model, with runoff and sediment output as driving data, and sub-basins as the basic computational unit, the sediment balance within the dam system is calculated by overlaying the water and sediment transport simulation results of each sub-basin with the silt-retaining dam network. In the case study, meteorological observation data from eight weather stations are used as the driving force to simulate the spatial process of watershed water and sediment, and the dynamic process of sediment interception by each silt-retaining dam is further presented. After the simulation, the simulation results are compared and analyzed. The cumulative sedimentation volume from silt-retaining dam survey statistics is used as the observed value to compare the simulation effect of the newly developed calculation method on sediment interception by silt-retaining dams. Figure 3 As shown. Overall, the cumulative sediment interception volume simulated by the calculation method of this patent is relatively close to the actual observed value, with the average simulated cumulative sediment deposition volume being 267,200 m³. 3 The average observed cumulative siltation volume is 239,700 m³. 3 The simulated values ​​are slightly higher than the observed values. The correlation between the simulated and observed values ​​is concentrated around the 1:1 line, and more than 60% of the simulation results for silt-retaining dams have a deviation within ±50%. The coefficient of determination R between the simulated and observed values... 2 With an NSE of 0.71, a Pbias of 0.53, and a Pbias of 11.5%, this calculation method can be rated as "satisfactory" for simulating sediment interception by silt-retaining dams in the case study watershed, based on internationally accepted model evaluation standards. It can be used for long-term spatiotemporal dynamic simulation of sediment interception by silt-retaining dams.

[0082] (5) Spatiotemporal data extraction and spatial visualization of sediment interception by watershed-scale silt-retaining dam systems

[0083] After the calculations were completed, the long-term erosion, sediment yield, and sediment retention dynamics of the case watershed were obtained. Figure 4 The spatial distribution of sediment retention by the dam system in the basin is shown in Figure 5 It can be seen that the annual sediment retention capacity of silt-retaining dams in the Yanhe River basin generally shows a non-monotonically increasing trend; after 1969, the sediment retention capacity of silt-retaining dams increased rapidly, reaching a peak in 1977, when the annual sediment retention capacity of silt-retaining dams reached 15.6 million cubic meters. 3 Subsequently, the annual sediment interception volume of silt-retaining dams showed a fluctuating decreasing trend; before the 1980s, the sediment interception volume showed an increasing trend, and then decreased; between 2010 and 2016, the annual sediment interception volume increased dramatically, mainly due to the erosion caused by heavy rainfall in the basin in 2013. In the loess hilly and gully area, heavy rainfall often triggers severe erosion disasters. The silt-retaining dam engineering measures located in the upper reaches of the basin can intercept gully sediment transport under severe erosion and sediment transport conditions, causing a surge in sediment interception volume that year.

[0084] Spatially, the erosion and sediment yield intensity in most sub-basins exceeded the allowable soil loss of the Loess Plateau, with the upper reaches of the Xingzi River and the Xichuan River being the key erosion and sediment-producing areas. The total sediment interception capacity of silt-retaining dams in most sub-basins was around 2.5 million cubic meters. 3 Below, the sediment retention capacity of silt-retaining dams in the sub-basins on both sides of the middle reaches of the main stream is relatively high, even reaching 5 million cubic meters. 3 The above indicates that the available reservoir capacity for silt-retention dams in most sub-basins is less than 500,000 m³. 3 The available reservoir capacity in the sub-basin surrounding Yan'an City in the middle reaches is relatively abundant, reaching 1 million cubic meters. 3 above.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dynamic calculation method for the sediment retention capacity of silt-trapping dams at the watershed scale, characterized in that, Includes the following steps: S1. Based on basic environmental information such as topography, hydrology, meteorology and land use, a distributed water and sediment process model is built at the watershed scale. S2. Perform parameter calibration and model verification on the spatially distributed water and sediment process model, and use spatiotemporal meteorological data to drive the spatially distributed simulation of long-term water and sediment processes. S3. Simplify the water and sediment interception process of each silt-retaining dam in the watershed silt-retaining dam system, and design the silt-retaining dam sediment interception module; If the silt-retaining dam is a terminal dam, the controlled area of ​​the silt-retaining dam is the actual controlled area at time t; if the silt-retaining dam is not a terminal dam, the runoff and sediment originate from the runoff and sediment discharged by the upstream silt-retaining dam and the inflow and sediment volume of the actual controlled area; after obtaining the upstream inflow and sediment volume of the non-terminal silt-retaining dam, the actual interception and discharge volume of runoff and sediment of each silt-retaining dam are calculated according to the calculation method of actual sediment interception by the terminal silt-retaining dam. S4. Drive the sediment-trapping dam module constructed in S3 using the water and sediment process data simulated in S2, and develop a data interaction framework between the water and sediment process model and the sediment-trapping dam module; The first step is to determine whether there is a silt-retention dam system in the sub-basin. If there is no silt-retention dam system in the sub-basin, the hydrological elements of the basin are calculated directly and the simulation results are output. If there is a silt-retention dam system in the sub-basin, the silt-retention dam variables are read and the upstream and downstream connection relationships of the silt-retention dam system are generated. The second step is to calculate from the end silt-collecting dam to the lower-level silt-collecting dams at a single moment until the calculation of all levels of silt-collecting dams is completed; after the calculation of the new siltation reservoir volume of all silt-collecting dams is completed, the siltation status of the silt-collecting dams is updated, and then the calculation of the next time point is entered until the calculation of the entire simulation process is completed. S5. Based on the data interaction framework developed by S4, dynamic simulation of sediment interception capacity of silt-retaining dams at the watershed scale is performed, and the simulation results are extracted to provide the spatiotemporal dynamics of sediment interception by silt-retaining dam systems at the watershed scale.

2. The method for dynamically calculating the sediment retention capacity of watershed-scale silt-trapping dams according to claim 1, characterized in that, In step S1, data on watershed elevation, land use, soil, and climate and hydrology are collected, model input database is prepared, and water and sediment process model is built using ArcSWAT software.

3. The method for dynamically calculating the sediment retention capacity of watershed-scale silt-trapping dams according to claim 1, characterized in that, In step S2, the water and sediment process model is calibrated and verified. After the model is established, in order to ensure that the simulated watershed hydrological conditions are under natural conditions, the simulation results need to be calibrated and verified. The first step is to collect and organize runoff and sediment observation data during the simulation period, and to determine the rate-setting period and the validation period; The second step is to select and adjust the parameters for runoff and sediment based on previous research experience and relevant measured data in the study area. The third step is to determine the parameter calibration method. Using SWAT-CUP software, the optimization of model parameters begins by inputting observation data, setting parameter ranges, inputting the number of iterations, and saving the data. Finally, based on the coefficient of determination R 2 The Nash coefficient (NSE) and percentage bias (PBIAS) are used as evaluation indicators to judge the model performance, with R... 2 The criteria for determining whether the simulation results are satisfactory are >0.5, NSE>0.5, and |PBIAS|≤30%, and the optimal parameters are finally determined.

4. The method for dynamically calculating the sediment retention capacity of watershed-scale silt-trapping dams according to claim 1, characterized in that, In step S5, the spatiotemporal data of sediment interception by silt-retaining dams at the watershed scale are extracted and spatially displayed. Based on the data interaction framework developed in S4, dynamic simulation of sediment interception by silt-retaining dams at the watershed scale is performed. The simulation results are extracted, and the spatiotemporal dynamics of sediment interception by silt-retaining dams at the watershed scale are given. Using the spatiotemporal analysis method of geospatial data, the spatiotemporal display and analysis of sediment interception are performed for sub-watersheds and individual silt-retaining dams respectively.

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