Data-free area runoff sediment transport simulation method and system based on SWAT model
By employing the parameter transfer method of the SWAT model in areas lacking data, simultaneous simulation of runoff and sediment transport was achieved. This solved the accuracy problem of assessing reservoir siltation and river evolution in areas without data, improved the reliability and applicability of the simulation results, and provided a scientific basis for water resources management and engineering planning.
Patent Information
- Application Number
- CN202511455235.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-13
- Publication Date
- 2026-01-13
AI Technical Summary
In areas lacking data, existing technologies struggle to simultaneously simulate runoff and sediment transport, leading to inaccurate assessments of reservoir siltation and river channel evolution, which in turn affects the safety and lifespan assessments of water conservancy projects.
The parameter transfer method based on the SWAT model is adopted. By selecting a data-rich watershed with similar geographical, climatic and underlying surface characteristics to the target watershed as a reference watershed, hydrological similarity calculation is performed, a reference watershed model is constructed and the parameters are calibrated. Then, the runoff and sediment transport parameters are jointly transferred to the target watershed to achieve synchronous simulation of runoff and sediment transport.
It enables simultaneous simulation of runoff and sediment transport in areas lacking data, improves the accuracy and applicability of simulation results, reduces reliance on measured data, and provides a reliable basis for water resource management and engineering planning.
Smart Images
Figure CN121328110A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of water conservancy engineering technology, and specifically relates to a method and system for simulating runoff and sediment transport in areas without data based on computer data processing, which is particularly applicable to fields such as smart water conservancy and water resource management. Background Technology
[0002] Small watersheds are crucial basic units for water resource management, ecological environmental protection, and socio-economic development. In recent years, my country has continuously strengthened the management of small watersheds. However, currently, small watersheds in my country generally suffer from sparse monitoring stations and a lack of data, making it impossible to obtain basic hydrological baseline data such as annual runoff and annual sediment load, leading to a series of problems. Especially in highly erosive areas such as the Loess Plateau, watershed sediment transport is intense, and floods are often accompanied by high-sediment-laden runoff, which not only affects the scheduling of downstream water conservancy projects but also threatens reservoir siltation and life assessment. In areas without data, how to use hydrological models to achieve water and sediment situation forecasting and improve its accuracy has always been a research hotspot and challenge in the hydrological community, and also a difficult point in small watershed management.
[0003] Currently, simulation studies for areas lacking data have made some progress. Using parameter regionalization methods based on similarity theory to transfer calibration parameters from data-rich watersheds to data-free watersheds is one of the most effective methods for solving this problem. However, existing technologies mostly focus on runoff process simulation. For small watersheds with severe soil erosion, sediment transport and runoff are equally important, especially in the Loess Plateau region, where sediment transport is crucial for the safety of water conservancy projects. The lack of joint simulation of sediment yield and runoff leads to the need to introduce empirical formulas or simplified models for sediment estimation when assessing reservoir siltation, river channel evolution, and the lifespan of water conservancy projects. This introduces secondary errors and reduces the reliability of the assessment results. Furthermore, current research on the simultaneous simulation and application of runoff and sediment transport is insufficient.
[0004] Therefore, there is an urgent need for a technical solution that can achieve simultaneous simulation of runoff and sediment transport even in the absence of measured data, so as to improve the applicability and prediction accuracy of watershed models and provide reliable support for regional water resources management.
[0005] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention proposes a method and system for simulating runoff and sediment transport in data-free areas based on the SWAT model. This simulation method and system enables simultaneous simulation of runoff and sediment transport in small watersheds in data-free areas.
[0007] A method for simulating runoff and sediment transport in data-free areas based on the SWAT model includes the following steps: S1. Target watershed selection and data collection: Select small watersheds in typical areas with no data as target watersheds, and systematically collect comprehensive geographic information datasets of the target watersheds; S2. Determination of reference watersheds: Using the parameter transfer method, based on the principle of hydrological similarity, watersheds with data that are similar to the target watershed in terms of geography, climate and underlying surface characteristics are selected as reference watersheds. Hydrological similarity is calculated using the hydrological similarity element calculation formula, and the optimal reference watershed is selected by grade according to the results. S3. Construction and Calibration of Reference Basin Model: Construct a SWAT model of the reference basin, and use measured runoff and sediment transport data to calibrate and verify the model parameters to ensure that the simulation accuracy of runoff and sediment transport meets the requirements. S4. Joint parameter transfer and target watershed simulation: The runoff and sediment transport parameters calibrated in the reference watershed are jointly transferred to the SWAT model of the target watershed to construct a water-sediment coupling simulation system for the target watershed and output the long-term series of annual runoff and sediment transport. S5. Results Output and Analysis: Output simulation results for analysis of watershed runoff-sediment transport relationships, water resource assessment, and engineering planning in areas without data.
[0008] Preferably, the target watershed of the typical small watershed is the small watershed around the Henan perimeter of the Sanmenxia Reservoir, which includes 14 tributaries flowing into the Yellow River and spans the administrative regions of Hubin District, Shanzhou District and Lingbao City of Sanmenxia City.
[0009] Preferably, the comprehensive geographic information dataset of the target watershed includes long-term DEM elevation data, land use type data, soil type data, soil attribute data, meteorological data, and hydrological data.
[0010] Preferably, the parameter transfer method is as follows: for the watershed without data to be selected, a watershed with data that is close to it or has similar attributes is selected as a reference watershed, and the model parameters after calibration in the reference watershed are transferred to the watershed without data to be selected, so as to simulate the hydrological process of the target watershed.
[0011] Preferably, the parameter transfer method uses the small watershed hydrological similarity method for calculation and judgment. The process of using the hydrological similarity element calculation formula is as follows: (1); In the formula: The hydrological index values for watershed A; The corresponding hydrological index values for watershed B; For hydrological similarity elements, These are elements within watershed A. For elements in watershed B, and For the corresponding hydrological similarity elements; (2); In the formula: Let be the coefficient of variation of the i-th indicator, also known as the standard deviation coefficient; For the first The standard deviation of the indicators; For the first The average of the indicators; (3); In the formula: Weights for each indicator in the watershed; (4); In the formula: S represents the hydrological similarity; assuming that there are in watershed A... It consists of several hydrological elements, and watershed B has several... Hydrological elements are composed of elements, and there exists a relationship between watersheds A and B. Similar hydrological elements constitute A number of hydrological similarity elements are denoted as .
[0012] Preferably, the evaluation criteria for the hydrological similarity S are as follows: if S(A,B) < 0.600, the hydrological similarity is evaluated as dissimilar; if 0.600 ≤ S(A,B) < 0.750, the hydrological similarity is evaluated as generally similar; if 0.750 ≤ S(A,B) < 0.800, the hydrological similarity is evaluated as relatively similar; if 0.800 ≤ S(A,B) < 0.950, the hydrological similarity is evaluated as basically similar; and if 0.950 ≤ S(A,B) ≤ 1.00, the hydrological similarity is evaluated as completely similar.
[0013] Preferably, the process of constructing the reference watershed SWAT model includes: basic data processing, sub-watershed division, hydrological response unit analysis, meteorological data processing input, and parameter calibration.
[0014] Furthermore, this invention also provides a runoff and sediment transport simulation system for data-free areas based on the SWAT model, which employs the above-mentioned method, including: The data acquisition module is used to acquire and store DEM, land use, soil, meteorological and hydrological data of the target watershed, and perform standardized preprocessing.
[0015] The reference watershed selection module calculates the similarity value of each candidate watershed based on the hydrological similarity algorithm and selects the optimal reference watershed.
[0016] The reference watershed model construction and calibration module is used to establish the SWAT model of the reference watershed and to perform joint calibration and accuracy verification of the reference watershed to ensure that the fitting accuracy of the simulated values meets the requirements of hydrological simulation.
[0017] The target watershed simulation module is used to construct the SWAT model of the target watershed and obtain the annual runoff and sediment transport of the target area.
[0018] The results output module is used to visualize the simulation results in the target watershed simulation module, including annual runoff and sediment transport and confidence intervals.
[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) Realize the synchronous simulation of runoff and sediment transport: By introducing runoff factor and sediment transport factor in similarity calculation, the joint simulation of runoff and sediment production processes can be realized in areas without data. This avoids the problem that traditional methods only focus on runoff and ignore sediment transport, making the simulation results more consistent with the water and sediment coupling characteristics of the actual watershed. (2) Improve the universality and reliability of parameter transfer: By combining runoff parameters and sediment transport parameters from the reference watershed and transferring them as a whole to the target watershed, the bias caused by single parameter transfer is significantly reduced, and the applicability and prediction accuracy of the model under data-free conditions are improved. (3) Reduced data dependence and computational cost, suitable for areas lacking data: This method can run on only basic data such as topography, meteorology, soil and land use, reducing the dependence on continuous measured hydrological and sediment data, and is particularly suitable for small watersheds with sparse monitoring stations and insufficient observation conditions. (4) Provide support for regional management and engineering planning: When planning and designing reservoirs, water diversion or hydropower projects, reservoir capacity verification, sedimentation prediction and engineering operation life analysis can be carried out based on the simulated multi-year runoff and sediment transport volume, providing a scientific basis for engineering construction and operation. Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the following description is only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a flowchart of parameter porting based on the SWAT model.
[0022] Figure 2 It is a reference map showing the geographical location of the watershed.
[0023] Figure 3This is a comparison chart of measured and simulated values of runoff sediment transport in the Bahe River Basin.
[0024] Figure 4 This is a comparison chart of measured and simulated values of runoff sediment transport in the Jianhe River Basin.
[0025] Figure 5 It refers to the annual runoff and sediment transport of the Hongnongjian River and Qinglongjian River in the target basin from 1970 to 2022.
[0026] Figure 6 These are the simulation results of the multi-year average flow and multi-year average sediment transport of the target watershed.
[0027] Figure 7 This is a flowchart of a data-free area runoff and sediment transport simulation system based on the SWAT model. Detailed Implementation
[0028] This invention proposes a method for simulating runoff and sediment transport in areas with no data. To facilitate understanding of this invention by those skilled in the art, the specific embodiments of this invention are described below with reference to the accompanying drawings.
[0029] First, a typical small watershed in a data-free area is selected as the target watershed. A comprehensive geographic information dataset for the target watershed is systematically collected, including long-term DEM elevation data, land use type data, soil type data, soil attribute data, meteorological data, and hydrological data. Then, using the parameter transfer method and based on the principle of hydrological similarity, a data-rich watershed with similar attributes to the target watershed is identified as a reference watershed. Next, a SWAT model of the reference watershed is constructed to simulate runoff and sediment yield, and the parameters are calibrated and validated. The validated runoff and sediment transport parameters from the reference watershed are then jointly transferred to the data-free small watershed, achieving simultaneous simulation of runoff and sediment transport in the data-free area. Finally, the simulation results of runoff and sediment transport are output.
[0030] Specifically, in this embodiment, a typical small watershed around the Sanmenxia Reservoir in the Loess Plateau is taken as the target watershed. This small watershed includes 14 tributaries flowing into the Yellow River and spans the administrative regions of Hubin District, Shanzhou District and Lingbao City of Sanmenxia City. There are no runoff and sediment transport observation stations, which is a typical area without data. Therefore, it is suitable for verifying the feasibility of the method described in this invention.
[0031] 1. Collection of relevant data for the target watershed The data mainly includes DEM elevation data, land use type data, soil type data, soil attribute data, meteorological data, and hydrological data. Data sources and detailed information are shown in Table 1.
[0032] Table 1 Data Sources
[0033] 2. Data Processing There are specific requirements for the data types and formats used in calculating watershed hydrological similarity, as well as in SWAT modeling and parameter validation. To achieve accurate simulation of runoff and sediment transport in areas without data, the acquired DEM elevation data, land use type maps, soil data type maps, meteorological data, soil attribute data, hydrological data, and watershed attribute data need to be standardized and preprocessed to meet operational requirements. The specific process is detailed in [link to documentation]. Figure 1 .
[0034] (1) Spatial data: Using ArcGIS software, the DEM elevation map, land use type map, and soil type map were cropped and projected with coordinates according to the target watershed. In this embodiment, the WGS_1984_UTM_Zone_46N projection coordinate system was used. The land use type map and soil type map were reclassified using ArcGIS to reduce the number of categories, which facilitates subsequent calculations and makes the model run more smoothly.
[0035] (2) Attribute Data: Attribute data processing includes meteorological data processing, soil attribute data processing, and measured hydrological data processing. Meteorological data processing involves converting measured daily meteorological data such as daily precipitation, daily maximum and minimum temperatures, solar radiation, relative humidity, and average wind speed into the required txt text format and creating an index table. Since there are missing measured meteorological data in this embodiment, the weather generator built into the SWAT model is used to fill in the gaps. The parameters required by the weather generator, such as the monthly average minimum temperature, average maximum temperature, monthly average rainfall, and standard deviation of rainfall, are calculated using SWATWeather software. After the calculation is completed, the results are input into the SWAT model meteorological database. Soil attribute data processing mainly involves soil physical attribute data (soil attributes include physical and chemical attributes; this paper simulates runoff and sediment production processes and does not consider chemical attributes). The physical attributes of the soil determine the water and air movement and migration process in the soil, which has an important impact on the hydrological response units of the watershed. The soil physical properties data, including the proportion of each soil type, surface reflectance, and conductivity, can be directly obtained from the World Soil Database (HWSD) soil dataset. Parameters such as effective water retention and soil wet bulk density can be calculated using SPAW software. The obtained SWAT model soil property data is then input into the soil database. Hydrological data is then formatted as needed for subsequent model parameter verification.
[0036] 3. Determination of the reference watershed Data on watershed attributes of small watersheds in the Henan periphery of the Sanmenxia Reservoir area and other potential reference watersheds were collected and organized to meet the needs of attribute similarity calculations. Combining watershed topographic features and simple similarity identification results between indicators, watershed attributes such as watershed area, river length, average elevation, average slope, soil type indicators, land use type indicators, and rainfall were selected as indicators for determining similar watershed attributes. Among these, watershed area, river length, and multi-year average rainfall can be obtained from the local hydrological bureau of the watershed, while the proportions of each land use type indicator, soil type indicator, average slope, and average elevation can be extracted using ArcGIS.
[0037] By comparing the collected data on various watershed attributes, it was found that the Hongnongjian River, located in the Henan periphery of the Sanmenxia Reservoir area, has a drainage area of 2087 km². 2 The Qinglongjian River basin, with a drainage area of 511 km², is the largest among other small river basins. 2 The target watershed is more than three times larger than the target watershed, therefore the Hongnongjian River basin was separated from other small watersheds to find similar watersheds. The Ba River basin and the Hongnongjian River basin share similar attributes in terms of drainage area, river length, average elevation, average slope, soil type, land use, and rainfall. The watershed attributes of the Jian River basin are similar to those of other small watersheds around the Sanmenxia Reservoir area, excluding the Hongnongjian River. Therefore, the Ba River basin and the Jian River basin were initially selected as reference watersheds for the target watershed. The watershed attributes of the target watershed and the selected reference watersheds are shown in Table 2, and the geographical locations of the Ba River basin and the Jian River basin are shown in Table 3. Figure 2 .
[0038] Table 2. Attributes of each watershed
[0039] The parameter transfer method uses the small watershed hydrological similarity method for calculation and judgment. The process of using the hydrological similarity element calculation formula is as follows: (1); In the formula: The hydrological index values for watershed A; The corresponding hydrological index values for watershed B; For hydrological similarity elements, These are elements within watershed A. For elements in watershed B, and For the corresponding hydrological similarity elements; (2); In the formula: For the first The coefficient of variation of an indicator, also known as the standard deviation coefficient; For the first The standard deviation of the indicators; For the first The average of the indicators; (3); In the formula: Weights for each indicator in the watershed; (4); In the formula: S represents the hydrological similarity; assuming that there are in watershed A... It consists of several hydrological elements, and watershed B has several... Hydrological elements are composed of elements, and there exists a relationship between watersheds A and B. Similar hydrological elements constitute A number of hydrological similarity elements are denoted as .
[0040] The watershed attribute indicators are standardized according to formula (1) and the weights of each watershed attribute are calculated according to formulas (2) and (3). The calculated similarity elements are then used to calculate the similarity. Its corresponding weight Substituting into formula (4) to calculate the watershed hydrological similarity, the similarity between the Bahe River Basin and the Hongnongjian River Basin is 0.89, and the similarity between the Jianhe River Basin and other small watersheds around the Sanmenxia Reservoir area is between 0.75 and 0.95.
[0041] Table 3. Watershed Similarity Evaluation Indicators
[0042] According to the watershed similarity evaluation indicators (Table 3), the results of the watershed hydrological similarity evaluation (Table 4) show that the Bahe River Basin and the Hongnongjian River Basin are basically similar watersheds, and the Jianhe River Basin is basically similar to the other 11 watersheds. Therefore, the Bahe River Basin and the Jianhe River Basin can be used as similar watersheds for studying various sub-watersheds, i.e., reference watersheds.
[0043] Table 4. Results of the watershed hydrological similarity assessment
[0044] 4. Construction of the SWAT model for the reference watershed and calibration and validation of simulation results. SWAT models were established for the reference watersheds, the Bahe River Basin (Maduwang Hydrological Station) and the Jianhe River Basin (Xin'an Hydrological Station), at a scale of 1960–2022 to simulate runoff and sediment production processes in the Bahe and Jianhe River Basins. The preheating period was set to 10 years (1960–1969). The simulation results were imported into SWAT-CUP software to calibrate and validate the reference watersheds, the Bahe and Jianhe Rivers, for a calibration period of 30 years (1970–1999) and a validation period of 23 years (2000–2022), respectively.
[0045] The coefficient of determination (R²) and Nash efficiency coefficient (NSE) are used to measure the goodness of fit and performance of the model. R² represents the degree of model fit to the data, ranging from 0 to 1; the closer the value is to 1, the better the model fit. NSE is used to validate the hydrological model simulation results; NSE values range from negative infinity to 1, with values closer to 1 indicating better simulation performance. The coefficients of determination (R²) for the rate-setting and validation periods of the Bahe River Basin and the Jianhe River Basin are shown below. 2 All are above 0.65, and the efficiency coefficients (NSE) are all above 0.6. (From...) Figure 3 and Figure 4 The comparison between the simulated and actual annual runoff and sediment transport process lines of the reference watershed can be observed. However, the original observation data for 1991-2000 is missing, and the measured and simulated values for this period were not compared. Overall, the simulated and measured process lines match well, reflecting the actual trends in runoff and sediment transport. In other words, the accuracy of the simulated values meets the requirements of hydrological simulation. Therefore, the SWAT model parameters of the Bahe River Basin and the Jianhe River Basin can be transferred to the corresponding similar watersheds.
[0046] 5. SWAT model simulation of runoff and sediment transport in the target watershed A SWAT model was established for the small watershed surrounding Henan Province in the Sanmenxia Reservoir area from 1960 to 2022. The parameters of the validated models from the Bahe River and Jianhe River basins were transferred into the model. After a 10-year warm-up period, the model was run to obtain the annual runoff and sediment transport for the small watershed surrounding Henan Province in the Sanmenxia Reservoir area from 1970 to 2022. Figure 5 The paper presents the simulation results of annual runoff and sediment transport for the Hongnongjian River and Qinglongjian River, with the Bahe River as the reference basin for the Hongnongjian River and the Jianhe River as the reference basin for the Qinglongjian River. The multi-year average flow and multi-year average sediment transport of each river in the small watershed are obtained by summarizing the data. Figure 6 ).
[0047] 6. Results Analysis and Application The simulation results obtained can be used for: (1) Prediction of reservoir siltation and analysis of reservoir capacity evolution; (2) Tracing sediment sources and delineating priority areas for treatment in small and medium-sized watersheds; (3) Evaluation of the benefits of regional water resource allocation and soil and water conservation projects.
[0048] Furthermore, such as Figure 7 As shown, this embodiment also provides a runoff and sediment transport simulation system for data-free areas capable of implementing the above method, including: The data acquisition module is used to acquire and store DEM, land use, soil, meteorological and hydrological data of the target watershed, and perform standardized preprocessing.
[0049] The reference watershed selection module calculates the similarity value of each candidate watershed based on the hydrological similarity algorithm and selects the optimal reference watershed.
[0050] The reference watershed model construction and calibration module is used to establish the SWAT model of the reference watershed and to perform joint calibration and accuracy verification of the reference watershed to ensure that the fitting accuracy of the simulated values meets the requirements of hydrological simulation.
[0051] The target watershed simulation module is used to construct the SWAT model of the target watershed and obtain the annual runoff and sediment transport of the target watershed.
[0052] The results output module is used to visualize the simulation results in the target watershed simulation module, including annual runoff and sediment transport and confidence intervals.
[0053] Furthermore, this embodiment introduces a dual-parameter joint calibration of "runoff-sediment transport" and an overall parameter transfer strategy, enabling the model to obtain highly reliable outputs even in areas without data, thus possessing significant engineering promotion value.
[0054] The embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A method for simulating runoff and sediment transport in data-free areas based on the SWAT model, characterized in that, Includes the following steps: S1. Target watershed selection and data collection: Select small watersheds in typical areas with no data as target watersheds, and systematically collect comprehensive geographic information datasets of the target watersheds; S2. Determination of reference watersheds: Using the parameter transfer method, based on the principle of hydrological similarity, watersheds with data that are similar to the target watershed in terms of geography, climate and underlying surface characteristics are selected as reference watersheds. Hydrological similarity is calculated using the hydrological similarity element calculation formula, and the optimal reference watershed is selected by grade according to the results. S3. Construction and Calibration of Reference Basin Model: Construct a SWAT model of the reference basin, and use measured runoff and sediment transport data to calibrate and verify the model parameters to ensure that the simulation accuracy of runoff and sediment transport meets the requirements. S4. Joint parameter transfer and target watershed simulation: The runoff and sediment transport parameters calibrated in the reference watershed are jointly transferred to the SWAT model of the target watershed to construct a water-sediment coupling simulation system for the target watershed and output the long-term series of annual runoff and sediment transport. S5. Results Output and Analysis: Output simulation results for analysis of watershed runoff-sediment transport relationships, water resource assessment, and engineering planning in areas without data.
2. The method for simulating runoff and sediment transport in data-free areas based on the SWAT model according to claim 1, characterized in that: The typical data-free area is the small watershed surrounding the Sanmenxia Reservoir in Henan Province, which includes 14 tributaries flowing into the Yellow River. It spans the administrative regions of Hubin District, Shanzhou District, and Lingbao City in Sanmenxia City. There are no runoff and sediment transport monitoring stations in this area, making it a typical data-free area.
3. The method for simulating runoff and sediment transport in data-free areas based on the SWAT model according to claim 1, characterized in that: The comprehensive geographic information dataset for the target watershed includes long-term DEM elevation data, land use type data, soil type data, soil attribute data, meteorological data, and hydrological data.
4. The method for simulating runoff and sediment transport in data-free areas based on the SWAT model according to claim 1, characterized in that: The parameter transfer method involves selecting a data-rich watershed that is close to or has similar properties as a reference watershed for the selected watershed without data. The model parameters calibrated in the reference watershed are then transferred to the selected watershed without data to simulate the hydrological processes of the target watershed.
5. The method for simulating runoff and sediment transport in data-free areas based on the SWAT model according to claim 4, characterized in that: The parameter transfer method selects watersheds with similar attributes as reference watersheds, and uses the small watershed hydrological similarity method for calculation and judgment. The process of using the hydrological similarity element calculation formula is as follows. （1） In the formula: The hydrological index values for watershed A; The corresponding hydrological index values for watershed B; For hydrological similarity elements, These are elements within watershed A. For elements in watershed B, and For the corresponding hydrological similarity elements; （2） In the formula: For the first The coefficient of variation of an indicator, also known as the standard deviation coefficient; For the first The standard deviation of the indicators; For the first The average of the indicators; （3） In the formula: Weights for each indicator in the watershed; （4） In the formula: S represents the hydrological similarity; assuming that there are in watershed A... It consists of several hydrological elements, and watershed B has several... Hydrological elements are composed of elements, and there exists a relationship between watersheds A and B. Similar hydrological elements constitute A number of hydrological similarity elements are denoted as .
6. The method for simulating runoff and sediment transport in data-free areas based on the SWAT model according to claim 5, characterized in that: The evaluation criteria for the hydrological similarity S are as follows: if S(A,B) < 0.600, the hydrological similarity is evaluated as dissimilar; if 0.600 ≤ S(A,B) < 0.750, the hydrological similarity is evaluated as generally similar; if 0.750 ≤ S(A,B) < 0.800, the hydrological similarity is evaluated as relatively similar. If 0.800 ≤ S(A,B) < 0.950, the hydrological similarity is evaluated as basically similar; if 0.950 ≤ S(A,B) ≤ 1.00, the hydrological similarity is evaluated as completely similar.
7. The method for simulating runoff and sediment transport in data-free areas based on the SWAT model according to claim 1, characterized in that: The process of constructing the reference watershed SWAT model includes basic data processing, sub-watershed division, unit analysis, meteorological data processing input, and parameter calibration.
8. A SWAT model-based runoff and sediment transport simulation system for data-free areas, used to execute the SWAT model-based runoff and sediment transport simulation method for data-free areas as described in any one of claims 1-7, characterized in that, include: The data acquisition module is used to acquire and store DEM, land use, soil, meteorological and hydrological data of the target watershed, and perform standardized preprocessing. The reference watershed selection module calculates the similarity value of each candidate watershed based on the hydrological similarity algorithm and selects the optimal reference watershed. The reference watershed model construction and calibration module is used to build a SWAT model of the reference watershed and perform joint calibration and accuracy verification on the reference watershed to ensure that the fitting accuracy of the simulated values meets the requirements of hydrological simulation. The target watershed simulation module is used to construct the SWAT model of the target watershed and obtain the annual runoff and sediment transport of the target watershed. The results output module is used to visualize the simulation results in the target watershed simulation module, including annual runoff and sediment transport and confidence intervals.