A method for assessing regional suitability of a farmland water erosion prevention and control technology

Abstract

The present application relates to the field of data processing, and more particularly to a farmland water erosion prevention and control technology regional suitability evaluation method, which comprises: obtaining basic terrain and flow direction parameters by hydrological feature preprocessing on spatial terrain data of a target evaluation region; obtaining a runoff synchronous convergence polarization factor by path length polarization analysis on actual water flow path length in an upstream connected grid set; obtaining a terrain convex acceleration response factor by convex acceleration response mapping processing on adjacent upstream and downstream grid slope change characteristics; obtaining a water erosion scouring comprehensive risk index by multiplicative correction processing on the basic scouring risk index and the terrain convex acceleration response factor; and performing regional suitability classification according to the above, and outputting the regional suitability classification result of the farmland water erosion prevention and control technology, so as to identify high-energy scouring risk points formed by runoff synchronous convergence and along-path convex acceleration superposition, and improve the accuracy of farmland water erosion prevention and control facility site selection and layout.

Description

Technical Field

[0001] This invention relates to the field of data processing technology, and in particular to a method for assessing the regional suitability of farmland water erosion control technology. Background Technology

[0002] Farmland water erosion control technologies, such as contour hedges and ecological interception ditches, typically require a regional suitability assessment of the target farmland area before deployment to determine the risk of surface runoff erosion at different spatial locations. Existing assessment methods mostly rely on hydrological analysis based on digital elevation model data. This involves counting the number of upstream connected grids flowing into the target grid using a flow direction matrix, calculating this as the cumulative upstream catchment area, and then combining this with the local slope of the target grid to construct a erosion risk index. These methods primarily rely on the logic that a larger catchment area and steeper local slope equate to a higher erosion risk for suitability assessment.

[0003] However, existing methods typically only count the number of upstream connected grids without considering the differences in path length distribution from each upstream grid to the target grid along the actual flow path when calculating the cumulative catchment area. In actual rainfall runoff generation, the path lengths of grids in a narrow and elongated catchment area vary considerably, resulting in relatively dispersed runoff arrival times. In contrast, in a compact fan-shaped or funnel-shaped catchment area, the path lengths of many grids are relatively similar, making it easier for runoff to arrive at the target grid synchronously and create a concentrated, instantaneous scouring effect. Existing methods struggle to distinguish the runoff convergence characteristics under these different catchment area morphologies.

[0004] Meanwhile, existing methods typically only use the partial slope of the target grid or the average slope of the catchment area to characterize topographic erosion conditions, without analyzing the slope changes between adjacent upstream and downstream grids along the flow direction. When surface runoff passes through convex terrain that transitions from gentle to steep, the flow velocity and erosion kinetic energy accumulate and accelerate; conversely, when passing through concave terrain that transitions from steep to gentle, the runoff kinetic energy is weakened. Due to the lack of extraction of the distribution characteristics of the flow path length and the convex acceleration characteristics along the slope, existing methods are prone to misclassifying areas with synchronous convergence and accelerated erosion risks as conventionally suitable areas. Therefore, improving the accuracy of identifying high-energy erosion risk points of instantaneous concentrated flow in the regional suitability assessment of farmland water erosion control technologies has become an urgent problem to be solved in this field. Summary of the Invention

[0005] In view of this, the present invention aims to propose a regional suitability assessment method for farmland water erosion control technology, in order to solve the problem that existing methods cannot identify the risk points of synchronous runoff convergence and accelerated erosion due to relying only on cumulative runoff area and local slope.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A method for assessing the regional suitability of farmland water erosion control technology, the method comprising:

[0008] Step S1: Obtain basic topographic and flow direction parameters by preprocessing the spatial topographic data of the target assessment area with hydrological features;

[0009] Step S2: Obtain the runoff synchronous convergence polarization factor by performing path length polarization analysis on the actual water flow path length in the upstream connected grid set;

[0010] Step S3: Obtain the terrain convex acceleration response factor by performing convex acceleration response mapping on the slope change characteristics of adjacent upstream and downstream grids in the upstream connected grid set;

[0011] Step S4: Obtain the comprehensive water erosion risk index by performing multiplicative correction on the basic erosion risk index and the topographic convexity acceleration response factor.

[0012] Step S5: By performing regional suitability classification on the comprehensive risk index of water erosion, the regional suitability classification results of farmland water erosion control technology are obtained.

[0013] Furthermore, the step of preprocessing the spatial topographic data of the target assessment area with hydrological features to obtain basic topographic and flow direction parameters includes:

[0014] The terrain of the target assessment area is scanned and collected by the airborne lidar of the UAV to obtain the digital elevation model data of the target assessment area. The actual physical area of ​​a single grid is obtained according to the spatial resolution of the digital elevation model data. The digital elevation model data is then filled to obtain the digital elevation model data after filling. Based on the digital elevation model data after filling, the water flow direction is identified to obtain the water flow direction matrix of the target assessment area.

[0015] For any target grid within the target assessment area, connected grids within the upstream complete catchment area corresponding to the target grid are extracted based on the water flow direction matrix, and the extracted connected grids are used as the upstream connected grid set corresponding to the target grid; the total number of grids contained in the upstream connected grid set is counted; for any upstream grid in the upstream connected grid set, the adjacent downstream grids along the water flow direction of the upstream grid are determined based on the water flow direction matrix, and the actual water flow path length from the upstream grid to the target grid along the actual surface water flow direction and the actual water flow path length from the adjacent downstream grid to the target grid are calculated;

[0016] By performing surface slope analysis on the digital elevation model data after filling depressions, the local slope angle of any upstream grid in the upstream connected grid set, the local slope angle of the adjacent downstream grid, and the local slope angle of the target grid are obtained. The digital elevation model data, the actual physical area of ​​a single grid, the water flow direction matrix, the upstream connected grid set, the total number of grids, the actual water flow path length, the local slope angle of the upstream grid, the local slope angle of the adjacent downstream grid, and the local slope angle of the target grid are used as basic topographic and flow direction parameters.

[0017] Furthermore, the step of obtaining the runoff synchronous convergence polarization factor by performing path length polarization analysis on the actual water flow path length in the upstream connected grid set includes:

[0018] By statistically organizing the upstream connected grid set and the actual water flow path length in the basic terrain and flow direction parameters, the distribution data of the water flow path length corresponding to the target grid is obtained.

[0019] By performing mean deviation normalization attenuation mapping on the water flow path length distribution data, the runoff synchronous convergence polarization factor is obtained.

[0020] Furthermore, the step of obtaining the water flow path length distribution data corresponding to the target grid by statistically processing the upstream connected grid set and the actual water flow path length in the basic terrain and flow direction parameters includes:

[0021] For any target grid cell, extract the upstream connected grid cell set corresponding to the target grid cell from the basic topography and flow direction parameters, and count the total number of grid cells contained in the upstream connected grid cell set; for any upstream grid cell in the upstream connected grid cell set, extract the actual water flow path length of the upstream grid cell to the target grid cell along the actual surface water flow direction from the basic topography and flow direction parameters, and associate the upstream grid cell with the corresponding actual water flow path length to obtain the upstream grid cell path length association data corresponding to the target grid cell;

[0022] The actual flow path lengths in the path length association data of all upstream grids corresponding to the target grid are summed, and the summation result is divided by the total number of grids in the upstream connected grid set. The resulting fraction is used as the arithmetic mean of the path lengths corresponding to the target grid. The maximum value of the actual flow path lengths in the path length association data of all upstream grids corresponding to the target grid is obtained by filtering. The upstream connected grid set, the total number of grids, the upstream grid path length association data, the arithmetic mean of the path lengths, and the maximum path length are used as the flow path length distribution data corresponding to the target grid.

[0023] Furthermore, the step of obtaining the runoff synchronous convergence polarization factor by performing mean deviation normalization attenuation mapping processing on the water flow path length distribution data includes:

[0024] For any target grid cell, extract the upstream connected grid cell set, the total number of grid cells, the upstream grid cell path length correlation data, the arithmetic mean of the path lengths, and the maximum path length from the water flow path length distribution data corresponding to the target grid cell; for any upstream grid cell in the upstream connected grid cell set, extract the actual water flow path length corresponding to the upstream grid cell from the upstream grid cell path length correlation data.

[0025] The difference between the actual water flow path length corresponding to the upstream grid and the arithmetic mean of the path length is used as the path length deviation assessment corresponding to the upstream grid; the calculation result of adding the maximum path length to a minimum constant to prevent the denominator from being zero is used as the path length normalization scale; the path length deviation assessment is used as the numerator, the path length normalization scale is used as the denominator, and the corresponding fraction is used as the normalized path length deviation assessment corresponding to the upstream grid.

[0026] The negative of the squared value of the deviation of the normalized path length from the evaluation is subjected to an exponential mapping with the natural constant as the base. The corresponding mapping result is used as the single-grid synchronous convergence weight of the upstream grid. The single-grid synchronous convergence weights of all upstream grids in the upstream connected grid set are summed, and the summation result is divided by the total number of grids. The corresponding fraction is used as the runoff synchronous convergence polarization factor of the target grid.

[0027] Furthermore, the step of obtaining the terrain convex acceleration response factor by performing convex acceleration response mapping processing on the slope change characteristics of adjacent upstream and downstream grids in the upstream connected grid set includes:

[0028] By performing slope correlation processing on the upstream connected grid set, adjacent downstream grid and local slope angle in the basic terrain and flow direction parameters, the slope change data of adjacent upstream and downstream grids can be obtained.

[0029] By performing convex slope increment filtering on the slope change data of the adjacent upstream and downstream grids, convex acceleration feature data is obtained.

[0030] The topographic convex acceleration response factor is obtained by performing distance attenuation coupling mapping on the convex acceleration feature data, actual water flow path length, and runoff synchronous convergence polarization factor.

[0031] Furthermore, the step of obtaining slope change data of adjacent upstream and downstream grids by performing slope correlation processing on the upstream connected grid set, adjacent downstream grids, and local slope angles in the basic terrain and flow direction parameters includes:

[0032] For any target grid, extract the upstream connected grid set corresponding to the target grid from the basic topography and flow direction parameters; for any upstream grid in the upstream connected grid set, extract the adjacent downstream grids of the upstream grid along the water flow direction from the basic topography and flow direction parameters, and associate the upstream grid with the corresponding adjacent downstream grids to obtain the adjacent upstream and downstream grid association data corresponding to the target grid.

[0033] The local slope angles of the upstream grid and the adjacent downstream grid are extracted from the basic terrain and flow direction parameters. The local slope angle of the upstream grid is taken as the upstream local slope angle, and the local slope angle of the adjacent downstream grid is taken as the downstream local slope angle. Tangent mapping is performed on the upstream and downstream local slope angles respectively to obtain the upstream slope tangent value corresponding to the upstream grid and the downstream slope tangent value corresponding to the adjacent downstream grid.

[0034] The upstream connected raster set corresponding to the target raster, the associated data of adjacent upstream and downstream raster, the upstream local slope angle, the downstream local slope angle, the upstream slope tangent value, and the downstream slope tangent value are used as the slope change data of the adjacent upstream and downstream raster corresponding to the target raster.

[0035] Furthermore, the step of obtaining convex acceleration feature data by performing convex slope increment filtering processing on the adjacent upstream and downstream grid slope change data includes:

[0036] For any target raster, extract the upstream connected raster set, the adjacent upstream and downstream raster correlation data, the upstream slope tangent value, and the downstream slope tangent value from the slope change data of the adjacent upstream and downstream raster corresponding to the target raster; for any upstream raster in the upstream connected raster set, determine the adjacent downstream raster corresponding to the upstream raster based on the adjacent upstream and downstream raster correlation data, and extract the upstream slope tangent value corresponding to the upstream raster and the downstream slope tangent value corresponding to the adjacent downstream raster.

[0037] The difference between the downstream slope tangent value corresponding to the adjacent downstream grid and the upstream slope tangent value corresponding to the upstream grid is used as the slope increment assessment corresponding to the upstream grid; when the slope increment assessment is less than a constant 0, the convex slope increment assessment corresponding to the upstream grid is set to a constant 0; when the slope increment assessment is greater than or equal to a constant 0, the slope increment assessment is used as the convex slope increment assessment corresponding to the upstream grid.

[0038] The upstream connected raster set corresponding to the target raster, the associated data of adjacent upstream and downstream raster, the slope increment assessment, and the convex slope increment assessment are used as the convex acceleration feature data corresponding to the target raster.

[0039] Furthermore, the step of obtaining the topographic convex acceleration response factor by performing distance attenuation coupling mapping processing on the convex acceleration feature data, actual water flow path length, and runoff synchronous convergence polarization factor includes:

[0040] For any target grid, extract the upstream connected grid set, adjacent upstream and downstream grid association data, and convex slope increment assessment from the convex acceleration feature data corresponding to the target grid, and obtain the runoff synchronous convergence polarization factor corresponding to the target grid; for any upstream grid in the upstream connected grid set, determine the adjacent downstream grid corresponding to the upstream grid based on the adjacent upstream and downstream grid association data, extract the convex slope increment assessment corresponding to the upstream grid from the convex acceleration feature data, and extract the actual flow path length from the adjacent downstream grid to the target grid from the basic topography and flow direction parameters;

[0041] Obtain the preset regional reference standard distance constant; use the regional reference standard distance constant as the numerator, and the calculation result of adding the regional reference standard distance constant to the actual water flow path length from the adjacent downstream grid to the target grid as the denominator, and use the corresponding fraction as the distance attenuation weight of the upstream grid; use the calculation result of multiplying the convex slope increment assessment of the upstream grid with the distance attenuation weight as the single grid convex acceleration response assessment of the upstream grid.

[0042] The convex acceleration response assessments of all upstream grids in the upstream connected grid set are summed to obtain the cumulative convex acceleration response assessment of the target grid. The result of adding the natural constant to the cumulative convex acceleration response assessment is used as the logarithmic smoothing input value of the target grid. The logarithmic smoothing input value is processed by natural logarithmic mapping to obtain the convex acceleration smoothing assessment of the target grid. The result of multiplying the runoff synchronous convergence polarization factor of the target grid with the convex acceleration smoothing assessment is used as the topographic convex acceleration response factor of the target grid.

[0043] Furthermore, the comprehensive water erosion risk index is obtained by performing multiplicative correction on the basic erosion risk index and the topographic convexity acceleration response factor, including:

[0044] For any target grid cell, extract the upstream connected grid cell set, total number of grid cells, actual physical area of ​​a single grid cell, and local slope angle of the target grid cell from the basic terrain and flow direction parameters, and obtain the terrain convexity acceleration response factor corresponding to the target grid cell.

[0045] The calculation result of multiplying the total number of grids corresponding to the target grid by the actual physical area of ​​a single grid is used as the upstream cumulative runoff physical area corresponding to the target grid; the local slope angle of the target grid is processed by sine mapping to obtain the local slope sine value corresponding to the target grid; the calculation result of multiplying the upstream cumulative runoff physical area by the local slope sine value is used as the basic scour risk index corresponding to the target grid.

[0046] The result of multiplying the basic scour risk index corresponding to the target grid with the topographic convexity acceleration response factor corresponding to the target grid is used as the comprehensive water erosion risk index corresponding to the target grid.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] This invention discloses a regional suitability assessment method for farmland water erosion control technology. By introducing the distribution characteristics of actual water flow path length within the upstream catchment area, it quantifies the synchronicity of runoff arrival in the target area, making suitability assessment no longer solely dependent on the scalar size of the upstream cumulative catchment area. For farmland slope areas with the same catchment area but different spatial morphologies, this invention can distinguish between elongated, dispersed catchment terrain and fan-shaped or funnel-shaped synchronous catchment terrain, avoiding misjudging areas with high risk of instantaneous concentrated flow as conventionally suitable areas, thereby improving the precision of farmland water erosion control facility site selection evaluation. Furthermore, this invention incorporates the characteristics of adjacent slope changes along the water flow direction to identify the water flow acceleration response caused by terrain transitioning from gentle to steep, and performs attenuation correction based on the actual water flow path distance between the acceleration location and the target area, enabling water erosion risk assessment to reflect the accumulation and consumption of kinetic energy along the runoff path. This allows for more accurate identification of high-risk grids on farmland slopes that are susceptible to the combined effects of synchronously converging water flow and near-end accelerated impact, providing more reliable data for the risk avoidance and regional configuration of water erosion control facilities such as contour hedges and ecological interception ditches. Attached Figure Description

[0049] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0050] Figure 1 This is a flowchart illustrating a method for assessing the regional suitability of a farmland water erosion control technology according to an embodiment of the present invention. Detailed Implementation

[0051] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0052] See Figure 1This is a flowchart of a method for assessing the regional suitability of farmland water erosion control technology according to Embodiment 1 of the present invention. Figure 1 As shown, a method for assessing the regional suitability of a farmland water erosion control technology may include:

[0053] Step S1: By performing hydrological feature preprocessing on the spatial topographic data of the target assessment area, basic topographic and flow direction parameters are obtained.

[0054] First, the target assessment area is scanned and collected using an airborne lidar from a UAV to obtain digital elevation model (DEM) data. Based on the spatial resolution of the DEM data, the actual physical area of ​​each grid cell is calculated. It should be noted that to ensure the macroscopic accuracy and timeliness of the regional assessment, the spatial resolution of the elevation data is set to 5 to 10 meters. In this embodiment, the elevation data resolution is set to 5 meters. The sampling update frequency is set to before spring planting or before a major rainfall season each year, thus accurately reflecting the true undulation of the current farmland surface. The DEM data is then processed to fill depressions, eliminating false closed depressions caused by measurement errors or small pits, resulting in a DEM data with filled depressions. Based on the filled DEM data, water flow direction identification is performed, and the D8 single-flow direction algorithm is used to calculate the water flow direction matrix of the target assessment area.

[0055] For any target grid within the target assessment area, connected grids within the upstream complete catchment area corresponding to the target grid are extracted based on the water flow direction matrix, and these extracted connected grids are used as the upstream connected grid set corresponding to the target grid. The total number of grids contained in the upstream connected grid set is counted. For any upstream grid in the upstream connected grid set, the adjacent downstream grids along the water flow direction of the upstream grid are determined based on the water flow direction matrix, and the actual water flow path length from the upstream grid to the target grid along the actual surface water flow direction and the actual water flow path length from the adjacent downstream grid to the target grid are calculated.

[0056] By performing surface slope analysis on the digital elevation model data after depression filling, the local slope angles of any upstream grid cell, adjacent downstream grid cells, and the target grid cell in the upstream connected grid set are obtained. The digital elevation model data, the actual physical area of ​​a single grid cell, the flow direction matrix, the upstream connected grid set, the total number of grid cells, the actual flow path length, the local slope angles of the upstream grid cells, the adjacent downstream grid cells, and the target grid cell are used as the basic topographic and flow direction parameters.

[0057] This completes the process of obtaining basic topographic and flow direction parameters by preprocessing the spatial topographic data of the target assessment area with hydrological characteristics.

[0058] Step S2: By performing path length polarization analysis on the actual water flow path length in the upstream connected grid set, the runoff synchronous convergence polarization factor is obtained.

[0059] In actual rainfall runoff processes, the time required for farmland surface runoff to flow from any location within the upstream catchment area to the target area directly depends on the actual flow path length from that location to the target area. Existing technologies, when assessing runoff intensity, only count the absolute number of connected grids within the catchment area, making it impossible to distinguish the order in which runoff arrives at the target area from different locations. When the catchment area has a compact fan shape or a wide funnel shape, it contains a large number of grids with similar flow path lengths to the target area. This special geometric arrangement causes the runoff generated by these grids to arrive at the target area synchronously within a very short time window after traveling almost the same flow distance, thus forming a concentrated flow of water far exceeding conventional drainage design, causing severe damage to water erosion control facilities. Conversely, when the catchment area has a long and narrow shape, the path lengths of the grids within it to the target area vary greatly, and the runoff arrival times are naturally staggered, preventing the formation of destructive concentrated flow. To address the problem of missed instantaneous peak flow rates caused by the lack of path feature extraction in existing algorithms... This step extracts the actual water flow path length data from all grids within the catchment area to the target area, and constructs a feature analysis mechanism that can measure the concentration of these path lengths in numerical distribution. By identifying the statistical polarization phenomenon of the water flow path length data near the mean, the process by which the spatial morphology of the catchment area leads to the synchronous arrival of runoff is accurately reconstructed from the data level, providing a basis for subsequent calibration suitability assessment results.

[0060] In summary, this invention first obtains the distribution data of water flow path lengths corresponding to target grids by statistically processing the upstream connected grid set and actual water flow path lengths in the basic topography and flow direction parameters. Specifically, for any target grid, the upstream connected grid set corresponding to the target grid is extracted from the basic topography and flow direction parameters, and the total number of grids contained in the upstream connected grid set is counted. For any upstream grid in the upstream connected grid set, the actual water flow path length from the upstream grid to the target grid along the actual surface water flow direction is extracted from the basic topography and flow direction parameters, and the upstream grid is associated with the corresponding actual water flow path length to obtain the upstream grid path length association data corresponding to the target grid. The actual water flow path lengths in all upstream grid path length association data corresponding to the target grid are summed, and the summation result is divided by the total number of grids contained in the upstream connected grid set. The resulting fraction is used as the arithmetic mean of the path lengths corresponding to the target grid. The maximum value of the actual water flow path lengths in all upstream grid path length association data corresponding to the target grid is obtained by maximum value filtering. The upstream connected grid set corresponding to the target grid, the total number of grids, the associated data of the upstream grid path length, the arithmetic mean of the path length, and the maximum path length are used as the water flow path length distribution data corresponding to the target grid.

[0061] After obtaining the flow path length distribution data corresponding to the target grid, the mean deviation normalization attenuation mapping process is further performed on the flow path length distribution data to obtain the runoff synchronous convergence polarization factor. Specifically, for any target grid, the upstream connected grid set, the total number of grids, the upstream grid path length correlation data, the arithmetic mean of path lengths, and the maximum path length are extracted from the flow path length distribution data corresponding to the target grid. For any upstream grid in the upstream connected grid set, the actual flow path length corresponding to the upstream grid is extracted from the upstream grid path length correlation data. The difference between the actual flow path length corresponding to the upstream grid and the arithmetic mean of path lengths is used as the path length deviation assessment corresponding to the upstream grid. The calculation result of adding the maximum path length to a minimal constant to prevent the denominator from being zero is used as the path length normalization scale. The path length deviation assessment is used as the numerator, the path length normalization scale is used as the denominator, and the corresponding fraction is used as the normalized path length deviation assessment corresponding to the upstream grid. The negative of the squared deviation of the normalized path length from the assessment is subjected to an exponential mapping with the natural constant as the base. The resulting mapping is used as the single-grid synchronous convergence weight for the upstream grid. The single-grid synchronous convergence weights for all upstream grids in the upstream connected grid set are summed, and the sum is divided by the total number of grids. The resulting fraction is used as the runoff synchronous convergence polarization factor for the target grid.

[0062] In one implementation, assume the first The set of upstream connected graticles corresponding to each graticle is: ;No. The corresponding grid cell is the first The upstream grid path length associated data is as follows: ;No. The arithmetic mean of the path lengths of the upstream connected raster sets corresponding to each raster is: ;No. The maximum path length corresponding to the upstream connected raster set of each raster is: ;No. The total number of rasters in the upstream connected raster set corresponding to each raster is: The minimum constant to prevent the denominator from being zero is: Then the first The formula for calculating the runoff synchronous convergence polarization factor corresponding to each grid cell is:

[0063]

[0064] in, Indicates the first The runoff synchronous convergence polarization factor corresponding to each grid; Indicates the first The set of upstream connected graticles corresponding to each graticle; Indicates the first The total number of rasters in the upstream connected raster set corresponding to each raster; Represents an exponential function with the natural constant as the base; Indicates the first The corresponding grid cell is the first Data associated with the path length of each upstream raster; Indicates the first The arithmetic mean of the path lengths of the upstream connected raster sets corresponding to each raster; Indicates the first The maximum path length corresponding to the upstream connected raster set of each raster; This represents a minimal constant used to prevent the denominator from being zero, and is set in the embodiments of the present invention. .

[0065] It should be noted that the polarization factor formula constructed in this step aims to quantify the concentration of runoff arrival time caused by topographic features during rainfall generation. In reality, whether runoff generated at a certain location can participate in forming an instantaneous peak flow that is destructive to flood control facilities depends on whether the time of the runoff's arrival at the target area coincides with the arrival time of the main flow in the catchment area. To reflect this process in the calculation, the formula first calculates the single-grid flow path length. Compared with the average water flow path length of the entire catchment area The difference, and using the maximum water flow path length The result is used as the denominator for normalized division. This part of the calculation characterizes the relative degree to which the runoff generated by the grid deviates from the main peak flow over time, eliminating the influence of differences in the absolute area of ​​different catchment areas on the path length value. After obtaining this degree of deviation, the formula calculates the square value of the deviation using the natural exponential function. When the terrain features are compact fan-shaped or funnel-shaped, the flow path length of a large number of grids is close to the average value. At this point, the path deviation value approaches zero, and the corresponding exponential function output value approaches 1. This indicates that because the water flow at these locations arrives at highly consistent times, the runoff they generate will be fully superimposed on the instantaneous peak flow, thus their weight is retained at its maximum value. Conversely, when the terrain is elongated, some grid cells, due to their extremely close or distant locations, arrive at the target area significantly earlier or later than the main water flow. In this case, the larger path deviation value will be numerically attenuated under the action of the negative exponential function, and the output value approaches 0. This objectively reflects that during rainfall, water flows arriving too early or too late will not have a substantial impact on the instantaneous concentrated scouring force because they are staggered from the convergence peak, and their weight is therefore reduced in the calculation. Finally, the formula introduces the reciprocal of the total number of grid cells. The summation of the exponential weights of all grid cells was averaged. This calculation resulted in the final calculated runoff synchronous convergence polarization factor. Instead of growing indefinitely with the absolute increase in the number of connected grids in the catchment area, it is transformed into a coefficient reflecting the local path length density distribution. This coefficient objectively reflects the degree to which the geometric spatial morphology of the catchment area stimulates the synchronous convergence state of water flow, thus compensating for the deficiency of existing algorithms in being unable to identify the convergence characteristics of non-uniform water flow.

[0066] Thus, the path length polarization analysis of the actual water flow path length in the upstream connected grid set was completed, and the runoff synchronous convergence polarization factor was obtained.

[0067] Step S3: Obtain the terrain convex acceleration response factor by performing convex acceleration response mapping on the slope change characteristics of adjacent upstream and downstream grids in the upstream connected grid set.

[0068] After determining the concentration of runoff arrival time using the runoff synchronization convergence polarization factor in step S2, it is necessary to further evaluate the velocity variation characteristics of the runoff during its flow along the surface, because the actual destructive force generated by synchronously arriving water is also affected by changes in slope along the path. Existing algorithms typically use the average slope of the catchment area or a single local slope of the target area when extracting slope features. This approach ignores the sequence of slope changes along the water flow topology. In farmland topography, when water flows downhill, if the upstream terrain exhibits a convex change from gentle to steep, the water flow will experience continuous acceleration in the steepening area, leading to a sharp increase in velocity and scouring force upon reaching the target area. Conversely, if the terrain exhibits a concave change from steep to gentle, the water flow velocity will naturally decrease as it passes through flatter areas. Conventional average slope values ​​cannot distinguish between these two terrain change states that have drastically different impacts on water flow velocity. In order to accurately assess the actual impact intensity of concentrated water flow, this step extracts the slope difference values ​​of adjacent grids along the direction of water flow based on the spatial morphological characteristics of the catchment area. Combined with the distance of the change location from the target area, a topographic convex acceleration response factor is constructed to quantify the superimposed impact of topographic convex changes along the flow on the acceleration state of the water flow.

[0069] In summary, this invention first performs slope correlation processing on the upstream connected grid set, adjacent downstream grids, and local slope angles in the basic topography and flow direction parameters to obtain slope change data of adjacent upstream and downstream grids. Specifically, for any target grid, the upstream connected grid set corresponding to the target grid is extracted from the basic topography and flow direction parameters. For any upstream grid in the upstream connected grid set, the adjacent downstream grids along the water flow direction of the upstream grid are extracted from the basic topography and flow direction parameters, and the upstream grids are correlated with their corresponding adjacent downstream grids to obtain the adjacent upstream and downstream grid correlation data corresponding to the target grid. The local slope angles of the upstream grid and the adjacent downstream grids are extracted from the basic topography and flow direction parameters, and the local slope angles of the upstream grids are taken as the upstream local slope angles, and the local slope angles of the adjacent downstream grids are taken as the downstream local slope angles. Tangent mapping processing is performed on the upstream local slope angles and the downstream local slope angles respectively to obtain the upstream slope tangent value corresponding to the upstream grid and the downstream slope tangent value corresponding to the adjacent downstream grid. The upstream connected raster set corresponding to the target raster, the associated data of adjacent upstream and downstream raster, the upstream local slope angle, the downstream local slope angle, the upstream slope tangent value, and the downstream slope tangent value are used as the slope change data of the adjacent upstream and downstream raster corresponding to the target raster.

[0070] After obtaining the slope change data of adjacent upstream and downstream grids, the convex slope increment filtering process is further performed on the adjacent upstream and downstream grid slope change data to obtain convex acceleration feature data. Specifically, for any target grid, the upstream connected grid set, adjacent upstream and downstream grid association data, upstream slope tangent value, and downstream slope tangent value are extracted from the slope change data of the adjacent upstream and downstream grids corresponding to the target grid. For any upstream grid in the upstream connected grid set, the adjacent downstream grid corresponding to the upstream grid is determined based on the adjacent upstream and downstream grid association data, and the upstream slope tangent value corresponding to the upstream grid and the downstream slope tangent value corresponding to the adjacent downstream grid are extracted. The difference between the downstream slope tangent value corresponding to the adjacent downstream grid and the upstream slope tangent value corresponding to the upstream grid is used as the slope increment evaluation corresponding to the upstream grid. When the slope increment evaluation is less than a constant 0, the convex slope increment evaluation corresponding to the upstream grid is set to a constant 0; when the slope increment evaluation is greater than or equal to a constant 0, the slope increment evaluation is used as the convex slope increment evaluation corresponding to the upstream grid. The upstream connected raster set corresponding to the target raster, the associated data of adjacent upstream and downstream raster, the slope increment assessment, and the convex slope increment assessment are used as the convex acceleration feature data corresponding to the target raster.

[0071] After obtaining the convex acceleration feature data corresponding to the target grid, the topographic convex acceleration response factor is obtained by performing distance attenuation coupling mapping on the convex acceleration feature data, actual flow path length, and runoff synchronous convergence polarization factor. Specifically, for any target grid, the upstream connected grid set, adjacent upstream and downstream grid association data, and convex slope increment assessment are extracted from the convex acceleration feature data corresponding to the target grid, and the runoff synchronous convergence polarization factor corresponding to the target grid is obtained. For any upstream grid in the upstream connected grid set, the adjacent downstream grid corresponding to the upstream grid is determined based on the adjacent upstream and downstream grid association data. The convex slope increment assessment corresponding to the upstream grid is extracted from the convex acceleration feature data, and the actual flow path length from the adjacent downstream grid to the target grid is extracted from the basic topography and flow direction parameters. A preset regional reference standard distance constant is obtained. In this embodiment of the invention, the regional reference standard distance constant is set to 50 meters. Considering the hydrodynamic characteristics of real farmland with gentle slopes, when water flow accelerates at a convex turning point in the terrain, after flowing over a gentle 50-meter stretch, the increased concentrated kinetic energy is usually consumed by soil roughness and vegetation friction. The regional reference standard distance constant is used as the numerator, and the result of adding the regional reference standard distance constant to the actual water flow path length from the adjacent downstream grid to the target grid is used as the denominator. The resulting fraction is used as the distance attenuation weight for the upstream grid. The result of multiplying the convex slope increment assessment corresponding to the upstream grid by the distance attenuation weight is used as the single-grid convex acceleration response assessment corresponding to the upstream grid. The single-grid convex acceleration response assessments corresponding to all upstream grids in the upstream connected grid set are summed to obtain the cumulative convex acceleration response assessment corresponding to the target grid. The result of adding the natural constant to the cumulative convex acceleration response assessment is used as the logarithmic smoothing input value for the target grid. The logarithmically smoothed input values ​​are processed by natural logarithmic mapping to obtain the convex acceleration smoothing assessment corresponding to the target raster. The result of multiplying the runoff synchronous convergence polarization factor corresponding to the target raster with the convex acceleration smoothing assessment is used as the terrain convex acceleration response factor corresponding to the target raster.

[0072] In one implementation, assume the first The local slope angle of each upstream grid is ;No. The local slope angle of each downstream grid is The regional reference standard distance constant is Then the first The formula for calculating the terrain convexity acceleration response factor corresponding to each grid cell is:

[0073]

[0074] in, Indicates the first The terrain convexity acceleration response factor corresponding to each grid cell; Indicates the first The runoff synchronous convergence polarization factor corresponding to each grid; Indicates the first The set of upstream connected graticles corresponding to each graticle; Indicates the first The downstream grid reaches the first The actual water flow path length of each grid cell; Denotes the natural constant e; This represents the logarithmic function with the natural constant e as the base. Represents the maximum value function; Indicates the first The local slope angle of each upstream grid; Indicates the relationship with the first The adjacent upstream grid along the direction of water flow is the first The local slope angle of each downstream grid; This represents the tangent function.

[0075] It should be noted that the topographic convexity acceleration response factor formula constructed in this step aims to address the problem that existing algorithms cannot identify the sequential acceleration or deceleration changes of water flow along the terrain. In the actual process of rainfall runoff, the acceleration of water flow often occurs in the transition zone where the terrain changes from gentle to steep, and whether this acceleration effect is consumed before reaching the target area depends on the spatial distance between the transition zone and the target area. To accurately quantify this topographic change characteristic, the formula first extracts the difference in topographic slope between the downstream and upstream grid cells. This difference reflects the rate of change of slope of the water flow in that local section. The formula then uses a maximum value function to filter this difference in one direction. When the water flow passes through a concave terrain that transitions from steep to gentle, the downstream slope is less than the upstream slope, resulting in a negative difference. The maximum value function forces this difference to zero, thus eliminating the interference of terrain deceleration on the accumulation result. When the water flow passes through a convex terrain that transitions from gentle to steep, the difference is positive, and the maximum value function retains it accurately. This design allows the formula to precisely identify all terrain turning points within the catchment area that cause water flow acceleration. After extracting the acceleration nodes, the formula introduces a spatial distance attenuation weight. If the convex acceleration node of the terrain occurs in a region extremely far upstream, i.e., at a distance... A larger value indicates a significantly lower weight. This reflects that even if upstream flow acceleration occurs, the increased velocity is gradually absorbed by surface friction over a long period of subsequent flow, resulting in a smaller impact on the target area. Conversely, if the acceleration node is adjacent to the target grid being evaluated... ,distance The values ​​approaching 0, and the weight values ​​approaching 1, indicate that the water flow directly impacts the target area without any buffering after acceleration, and its superimposed effects are fully preserved. Finally, the formula sums the values ​​of all acceleration nodes after distance weighting, smooths the data using a logarithmic function, and multiplies it by the runoff synchronous convergence polarization factor calculated in step S2 to establish a comprehensive evaluation mechanism: only when the upstream catchment area simultaneously possesses a compact shape that leads to synchronous water flow arrival and the topographic convex acceleration characteristics of the adjacent target area, will the final output topographic convex acceleration response factor be [value missing]. This process yields significantly high values. Through this process, the present invention quantifies the flow direction sequence and the state of water flow along the flow path, which cannot be extracted by existing methods, providing accurate numerical basis for revising suitability assessment results.

[0076] Thus, the convex acceleration response factor of the terrain is obtained by performing convex acceleration response mapping on the slope change characteristics of adjacent upstream and downstream grids in the upstream connected grid set.

[0077] Step S4: The comprehensive risk index of water erosion is obtained by performing multiplicative correction on the basic erosion risk index and the topographic convexity acceleration response factor.

[0078] This step applies the topographic convex acceleration response factor, constructed in the previous two steps, to the existing basic scour risk index. Through multiplicative correction, the originally isolated local static index is transformed into a comprehensive dynamic index that incorporates the upstream flow path length distribution characteristics and the cumulative characteristics of topographic convex acceleration along the path. When the upstream terrain of the target grid is prone to causing synchronous flow convergence and convex acceleration exists along the path, this correction method can directly and significantly amplify its basic risk value at the numerical level, thereby accurately correcting the evaluation bias of existing algorithms in complex farmland terrain.

[0079] Specifically, for any target grid, the upstream connected grid set, total number of grids, actual physical area of ​​a single grid, and local slope angle of the target grid are extracted from the basic topographic and flow direction parameters. The topographic convexity acceleration response factor corresponding to the target grid is also obtained. The result of multiplying the total number of grids corresponding to the target grid by the actual physical area of ​​a single grid is taken as the upstream cumulative runoff physical area corresponding to the target grid. The local slope angle of the target grid is sinusoidally mapped to obtain the local slope sine value corresponding to the target grid. The result of multiplying the upstream cumulative runoff physical area by the local slope sine value is taken as the basic scour risk index corresponding to the target grid. The result of multiplying the basic scour risk index corresponding to the target grid by the topographic convexity acceleration response factor corresponding to the target grid is taken as the comprehensive water erosion scour risk index corresponding to the target grid.

[0080] In one implementation, assume the first The local slope angle of each grid is The actual physical area of ​​a single grid cell is Then the first The formula for calculating the basic scour risk index of a grid is:

[0081]

[0082] in, Indicates the first The basic scour risk index of each grid; Indicates the first The total number of rasters in the upstream connected raster set corresponding to each raster; This represents the actual physical area of ​​a single grid cell; Indicates the first The local slope angle of each grid cell; This represents the sine function.

[0083] Furthermore, the first The formula for calculating the comprehensive risk index of water erosion of a grid is:

[0084]

[0085] in, Indicates the first The comprehensive risk index of water erosion and scouring of each grid; Indicates the first The basic scour risk index of each grid; Indicates the first The terrain convexity acceleration response factor corresponding to each grid cell.

[0086] It should be noted that the basic logic of the existing formula lies in multiplying the accumulated water volume upstream by the local gravitational acceleration component at the target location to quantify the basic scour kinetic energy of the surface runoff at that point under normal, steady flow conditions. In the formula, the basic scour risk index... The basic volume and local potential energy of runoff collection at the target grid are provided, ensuring the accuracy of the assessment method in determining macroscopic water volume. The topographic convexity acceleration response factor, acting as a correction multiplier, is determined by the geometric polarization state of the upstream catchment area (whether it arrives synchronously) and the first-order difference of the slope of the flow topology (whether it accelerates the impact). When the upstream of the target grid is a safe, narrow, and gently decelerating terrain, the value of the topographic convexity acceleration response factor is small, and the comprehensive risk index calculated by the formula is... Staying within the normal range indicates that the area will not generate unexpected instantaneous destructive force. However, when the upstream of the target grid presents a compact fan shape with a nearby steep, accelerating cliff, the value of the terrain convexity acceleration response factor will be significantly greater than 1. Through multiplication, the formula forcibly amplifies the basic risk value of the target grid. This correction mechanism eliminates the blind spot of the original assessment model in recognizing terrains of different shapes with equal areas, resulting in a more accurate and comprehensive risk index in the final output. It can accurately reflect the extreme concentrated water flow scouring force that the point experiences during rainfall runoff.

[0087] Thus, the comprehensive risk index of water erosion was obtained by performing multiplicative correction on the basic erosion risk index and the topographic convexity acceleration response factor.

[0088] Step S5: By performing regional suitability classification on the comprehensive risk index of water erosion, the regional suitability classification results of farmland water erosion control technology are obtained.

[0089] After obtaining the comprehensive risk index of water erosion for each target grid within the target assessment area, the comprehensive risk indexes of all target grids are statistically analyzed to form spatial distribution data of the comprehensive risk index of water erosion for the target assessment area. Based on a preset regional suitability grading threshold, the comprehensive risk index of water erosion for each target grid is graded to determine the regional suitability category of farmland water erosion control technology for each target grid.

[0090] Specifically, for any target grid, the comprehensive risk index of water erosion corresponding to the target grid is compared with preset low-risk, medium-risk, and high-risk thresholds. When the comprehensive risk index of water erosion is less than or equal to the low-risk threshold, the target grid is determined to be a high-suitability area, indicating that the runoff convergence and convex acceleration along the path at the location of the target grid are relatively weak, and it is suitable to deploy conventional farmland water erosion control facilities such as contour hedges and ecological interception ditches. When the comprehensive risk index of water erosion is greater than the low-risk threshold and less than or equal to the medium-risk threshold, the target grid is determined to be a medium-suitability area, indicating that there is a certain risk of erosion at the location of the target grid, and it is suitable to construct conventional farmland water erosion control facilities such as contour hedges and ecological interception ditches. The target grid should be deployed in accordance with conventional water erosion control facilities and local reinforcement measures. When the comprehensive risk index of water erosion is greater than the medium risk threshold but less than or equal to the high risk threshold, the target grid is determined to be a low-suitability area, indicating that there is a strong risk of concentrated runoff erosion at the location corresponding to the target grid, and it is not advisable to directly deploy ordinary lateral interception facilities alone. When the comprehensive risk index of water erosion is greater than the high risk threshold, the target grid is determined to be an unsuitable area, indicating that there is a high-energy erosion risk at the location corresponding to the target grid caused by the synchronous convergence of runoff and the acceleration of topographic convexity. Conventional farmland water erosion control facilities should be avoided, or enhanced control measures such as drainage, energy dissipation, and reinforcement should be given priority.

[0091] After classifying all target grids, the spatial location of each target grid is associated with its corresponding regional suitability category, generating regional suitability distribution data for farmland water erosion control technologies in the target assessment area. This regional suitability distribution data is then converted into a visual grid map, a classification statistical table, or a facility layout suggestion layer. This allows agricultural managers to intuitively identify suitable, cautiously implemented, and avoidable spatial locations within the target assessment area, thereby obtaining the regional suitability classification results for farmland water erosion control technologies.

[0092] Thus, the regional suitability classification results for farmland water erosion control technologies were obtained by performing regional suitability classification on the comprehensive risk index of water erosion.

[0093] 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 method for assessing the regional suitability of farmland water erosion control technology, characterized in that, The method includes: Step S1: Obtain basic topographic and flow direction parameters by preprocessing the spatial topographic data of the target assessment area with hydrological features; Step S2: Obtain the runoff synchronous convergence polarization factor by performing path length polarization analysis on the actual water flow path length in the upstream connected grid set; Step S3: Obtain the terrain convex acceleration response factor by performing convex acceleration response mapping on the slope change characteristics of adjacent upstream and downstream grids in the upstream connected grid set; Step S4: Obtain the comprehensive water erosion risk index by performing multiplicative correction on the basic erosion risk index and the topographic convexity acceleration response factor. Step S5: By performing regional suitability classification on the comprehensive risk index of water erosion, the regional suitability classification results of farmland water erosion control technology are obtained.

2. The method for regional suitability assessment of farmland water erosion control technology according to claim 1, characterized in that, The process of preprocessing the spatial topographic data of the target assessment area with hydrological features to obtain basic topographic and flow direction parameters includes: The terrain of the target assessment area is scanned and collected by the airborne lidar of the UAV to obtain the digital elevation model data of the target assessment area. The actual physical area of ​​a single grid is obtained according to the spatial resolution of the digital elevation model data. The digital elevation model data is then filled to obtain the digital elevation model data after filling. Based on the digital elevation model data after filling, the water flow direction is identified to obtain the water flow direction matrix of the target assessment area. For any target grid within the target assessment area, connected grids within the upstream complete catchment area corresponding to the target grid are extracted based on the water flow direction matrix, and the extracted connected grids are used as the upstream connected grid set corresponding to the target grid; the total number of grids contained in the upstream connected grid set is counted; for any upstream grid in the upstream connected grid set, the adjacent downstream grids along the water flow direction of the upstream grid are determined based on the water flow direction matrix, and the actual water flow path length from the upstream grid to the target grid along the actual surface water flow direction and the actual water flow path length from the adjacent downstream grid to the target grid are calculated; By performing surface slope analysis on the digital elevation model data after filling depressions, the local slope angle of any upstream grid in the upstream connected grid set, the local slope angle of the adjacent downstream grid, and the local slope angle of the target grid are obtained. The digital elevation model data, the actual physical area of ​​a single grid, the water flow direction matrix, the upstream connected grid set, the total number of grids, the actual water flow path length, the local slope angle of the upstream grid, the local slope angle of the adjacent downstream grid, and the local slope angle of the target grid are used as basic topographic and flow direction parameters.

3. The method for regional suitability assessment of farmland water erosion control technology according to claim 1, characterized in that, The method of obtaining the runoff synchronous convergence polarization factor by performing path length polarization analysis on the actual water flow path length in the upstream connected grid set includes: By statistically organizing the upstream connected grid set and the actual water flow path length in the basic terrain and flow direction parameters, the distribution data of the water flow path length corresponding to the target grid is obtained. By performing mean deviation normalization attenuation mapping on the water flow path length distribution data, the runoff synchronous convergence polarization factor is obtained.

4. The method for regional suitability assessment of farmland water erosion control technology according to claim 3, characterized in that, The process involves statistically processing the upstream connected grid set and actual water flow path lengths from the basic terrain and flow direction parameters to obtain the water flow path length distribution data corresponding to the target grid, including: For any target grid cell, extract the upstream connected grid cell set corresponding to the target grid cell from the basic topography and flow direction parameters, and count the total number of grid cells contained in the upstream connected grid cell set; for any upstream grid cell in the upstream connected grid cell set, extract the actual water flow path length of the upstream grid cell to the target grid cell along the actual surface water flow direction from the basic topography and flow direction parameters, and associate the upstream grid cell with the corresponding actual water flow path length to obtain the upstream grid cell path length association data corresponding to the target grid cell; The actual flow path lengths in the path length association data of all upstream grids corresponding to the target grid are summed, and the summation result is divided by the total number of grids in the upstream connected grid set. The resulting fraction is used as the arithmetic mean of the path lengths corresponding to the target grid. The maximum value of the actual flow path lengths in the path length association data of all upstream grids corresponding to the target grid is obtained by filtering. The upstream connected grid set, the total number of grids, the upstream grid path length association data, the arithmetic mean of the path lengths, and the maximum path length are used as the flow path length distribution data corresponding to the target grid.

5. The method for regional suitability assessment of farmland water erosion control technology according to claim 3, characterized in that, The step of obtaining the runoff synchronous convergence polarization factor by performing mean deviation normalization attenuation mapping processing on the water flow path length distribution data includes: For any target grid cell, extract the upstream connected grid cell set, the total number of grid cells, the upstream grid cell path length correlation data, the arithmetic mean of the path lengths, and the maximum path length from the water flow path length distribution data corresponding to the target grid cell; for any upstream grid cell in the upstream connected grid cell set, extract the actual water flow path length corresponding to the upstream grid cell from the upstream grid cell path length correlation data. The difference between the actual water flow path length corresponding to the upstream grid and the arithmetic mean of the path length is used as the path length deviation assessment corresponding to the upstream grid; the calculation result of adding the maximum path length to a minimum constant to prevent the denominator from being zero is used as the path length normalization scale; the path length deviation assessment is used as the numerator, the path length normalization scale is used as the denominator, and the corresponding fraction is used as the normalized path length deviation assessment corresponding to the upstream grid. The negative of the squared value of the deviation of the normalized path length from the evaluation is subjected to an exponential mapping with the natural constant as the base. The corresponding mapping result is used as the single-grid synchronous convergence weight of the upstream grid. The single-grid synchronous convergence weights of all upstream grids in the upstream connected grid set are summed, and the summation result is divided by the total number of grids. The corresponding fraction is used as the runoff synchronous convergence polarization factor of the target grid.

6. The method for regional suitability assessment of farmland water erosion control technology according to claim 1, characterized in that, The process of obtaining the terrain convex acceleration response factor by performing convex acceleration response mapping on the slope variation characteristics of adjacent upstream and downstream grids in the upstream connected grid set includes: By performing slope correlation processing on the upstream connected grid set, adjacent downstream grid and local slope angle in the basic terrain and flow direction parameters, the slope change data of adjacent upstream and downstream grids can be obtained. By performing convex slope increment filtering on the slope change data of the adjacent upstream and downstream grids, convex acceleration feature data is obtained. The topographic convex acceleration response factor is obtained by performing distance attenuation coupling mapping on the convex acceleration feature data, actual water flow path length, and runoff synchronous convergence polarization factor.

7. The method for assessing the regional suitability of farmland water erosion control technology according to claim 6, characterized in that, The process involves correlation processing of the upstream connected grid set, adjacent downstream grids, and local slope angles in the basic terrain and flow direction parameters to obtain slope change data of adjacent upstream and downstream grids, including: For any target grid, extract the upstream connected grid set corresponding to the target grid from the basic topography and flow direction parameters; for any upstream grid in the upstream connected grid set, extract the adjacent downstream grids of the upstream grid along the water flow direction from the basic topography and flow direction parameters, and associate the upstream grid with the corresponding adjacent downstream grids to obtain the adjacent upstream and downstream grid association data corresponding to the target grid. The local slope angles of the upstream grid and the adjacent downstream grid are extracted from the basic terrain and flow direction parameters. The local slope angle of the upstream grid is taken as the upstream local slope angle, and the local slope angle of the adjacent downstream grid is taken as the downstream local slope angle. Tangent mapping is performed on the upstream and downstream local slope angles respectively to obtain the upstream slope tangent value corresponding to the upstream grid and the downstream slope tangent value corresponding to the adjacent downstream grid. The upstream connected raster set corresponding to the target raster, the associated data of adjacent upstream and downstream raster, the upstream local slope angle, the downstream local slope angle, the upstream slope tangent value, and the downstream slope tangent value are used as the slope change data of the adjacent upstream and downstream raster corresponding to the target raster.

8. The method for regional suitability assessment of farmland water erosion control technology according to claim 6, characterized in that, The step of obtaining convex acceleration feature data by performing convex slope increment filtering on the slope change data of the adjacent upstream and downstream grids includes: For any target raster, extract the upstream connected raster set, the adjacent upstream and downstream raster correlation data, the upstream slope tangent value, and the downstream slope tangent value from the slope change data of the adjacent upstream and downstream raster corresponding to the target raster; for any upstream raster in the upstream connected raster set, determine the adjacent downstream raster corresponding to the upstream raster based on the adjacent upstream and downstream raster correlation data, and extract the upstream slope tangent value corresponding to the upstream raster and the downstream slope tangent value corresponding to the adjacent downstream raster. The difference between the downstream slope tangent value corresponding to the adjacent downstream grid and the upstream slope tangent value corresponding to the upstream grid is used as the slope increment assessment corresponding to the upstream grid; when the slope increment assessment is less than a constant 0, the convex slope increment assessment corresponding to the upstream grid is set to a constant 0; when the slope increment assessment is greater than or equal to a constant 0, the slope increment assessment is used as the convex slope increment assessment corresponding to the upstream grid. The upstream connected raster set corresponding to the target raster, the associated data of adjacent upstream and downstream raster, the slope increment assessment, and the convex slope increment assessment are used as the convex acceleration feature data corresponding to the target raster.

9. The method for regional suitability assessment of farmland water erosion control technology according to claim 6, characterized in that, The method involves performing distance attenuation coupling mapping on the convex acceleration feature data, actual water flow path length, and runoff synchronous convergence polarization factor to obtain the topographic convex acceleration response factor, including: For any target grid, extract the upstream connected grid set, adjacent upstream and downstream grid association data, and convex slope increment assessment from the convex acceleration feature data corresponding to the target grid, and obtain the runoff synchronous convergence polarization factor corresponding to the target grid; for any upstream grid in the upstream connected grid set, determine the adjacent downstream grid corresponding to the upstream grid based on the adjacent upstream and downstream grid association data, extract the convex slope increment assessment corresponding to the upstream grid from the convex acceleration feature data, and extract the actual flow path length from the adjacent downstream grid to the target grid from the basic topography and flow direction parameters; Obtain the preset regional reference standard distance constant; use the regional reference standard distance constant as the numerator, and the calculation result of adding the regional reference standard distance constant to the actual water flow path length from the adjacent downstream grid to the target grid as the denominator, and use the corresponding fraction as the distance attenuation weight of the upstream grid; use the calculation result of multiplying the convex slope increment assessment of the upstream grid with the distance attenuation weight as the single grid convex acceleration response assessment of the upstream grid. The convex acceleration response assessments of all upstream grids in the upstream connected grid set are summed to obtain the cumulative convex acceleration response assessment of the target grid. The result of adding the natural constant to the cumulative convex acceleration response assessment is used as the logarithmic smoothing input value of the target grid. The logarithmic smoothing input value is processed by natural logarithmic mapping to obtain the convex acceleration smoothing assessment of the target grid. The result of multiplying the runoff synchronous convergence polarization factor of the target grid with the convex acceleration smoothing assessment is used as the topographic convex acceleration response factor of the target grid.

10. The method for regional suitability assessment of farmland water erosion control technology according to claim 1, characterized in that, The process involves multiplicatively correcting the basic erosion risk index with the topographic convexity acceleration response factor to obtain the comprehensive water erosion risk index, including: For any target grid cell, extract the upstream connected grid cell set, total number of grid cells, actual physical area of ​​a single grid cell, and local slope angle of the target grid cell from the basic terrain and flow direction parameters, and obtain the terrain convexity acceleration response factor corresponding to the target grid cell. The calculation result of multiplying the total number of grids corresponding to the target grid by the actual physical area of ​​a single grid is used as the upstream cumulative runoff physical area corresponding to the target grid; the local slope angle of the target grid is processed by sine mapping to obtain the local slope sine value corresponding to the target grid; the calculation result of multiplying the upstream cumulative runoff physical area by the local slope sine value is used as the basic scour risk index corresponding to the target grid. The result of multiplying the basic scour risk index corresponding to the target grid with the topographic convexity acceleration response factor corresponding to the target grid is used as the comprehensive water erosion risk index corresponding to the target grid.

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