{"type": "FeatureCollection", "features": [{"id": "10.1016/j.catena.2021.105818", "type": "Feature", "geometry": null, "properties": {"updated": "2026-06-26T16:17:09Z", "type": "Journal Article", "created": "2021-11-13", "title": "An optimized method for extracting slope length in RUSLE from raster digital elevation", "description": "Abstract   The Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE) have been widely used for predicting average soil loss. Slope length is an important topographical parameter of the L factor in USLE/RUSLE. Among the widely studied GIS procedures for extracting slope length, the distributed watershed erosion slope length (DWESL) based on the unit contributing area estimation method, which considers two-dimensional runoff process and cutoff factors, is a relatively complete model for calculating slope length. Slope length in the DWESL model is primarily calculated using conventional flow direction algorithms such as D8, Dinf, MS and MFD-md. However, DWESL outputs require further improvement due to the errors in the usual estimates of the uphill contributing area and the effective contour length of discrete elements. Combined with a theoretical differential equation of specific catchment area on hillsides, the calculation of the DWESL model was optimized without estimating the uphill contributing area or the effective contour length for each cell. The proposed integration method based on the topographical features slope line, contour curvature and cutoff factors (ITF method) was used to extract slope length from the raster digital elevation. Slope length extracted using the ITF method had the smallest error in verification of mathematical surfaces (average RRMSE \u00a0=\u00a00.0573), and its spatial distribution was more consistent with the structure of the terrain surface for all test data, relative to the conventional flow direction algorithms in the original DWESL model. The proposed ITF method could provide a reference for predicting soil erosion using the USLE/RUSLE model.", "keywords": ["Slope Length", "Soil erosion", "0211 other engineering and technologies", "0401 agriculture", " forestry", " and fisheries", "RUSLE", "Terrain analysis", "04 agricultural and veterinary sciences", "02 engineering and technology", "15. Life on land", "GIS"]}, "links": [{"href": "https://doi.org/10.1016/j.catena.2021.105818"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/CATENA", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.catena.2021.105818", "name": "item", "description": "10.1016/j.catena.2021.105818", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.catena.2021.105818"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2022-02-01T00:00:00Z"}}, {"id": "10.1016/j.geoderma.2017.08.006", "type": "Feature", "geometry": null, "properties": {"updated": "2026-06-26T16:17:51Z", "type": "Journal Article", "created": "2017-08-30", "title": "An improved method for calculating slope length (\u03bb) and the LS parameters of the Revised Universal Soil Loss Equation for large watersheds", "description": "Abstract   The Universal Soil Loss Equation (USLE) and its revised version (RUSLE) are often used to estimate soil erosion at regional landscape scales. USLE/RUSLE contain parameters for slope length factor (L) and slope steepness factor (S), usually combined as LS. However a major limitation is the difficulty in extracting the LS factor. Methods to estimate LS based on geographic information systems have been developed in the last two decades. L can be calculated for large watersheds using the unit contributing area (UCA) or the slope length (\u03bb) as input parameters. Due to the absence of an estimation of slope length, the UCA method is insufficiently accurate. Improvement of the spatial accuracy of slope length and LS factor is still necessary for estimating soil erosion. The purpose of this study was to develop an improved method to estimate the slope length and LS factor. We combined the algorithm for multiple-flow direction (MFD) used in the UCA method with the LS-TOOL (LS-TOOLSFD) algorithms, taking into account the calculation errors and cutoff conditions for distance, to obtain slope length (\u03bb) and the LS factor. The new method, LS-TOOLMFD, was applied and validated in a catchment with complexly variable slopes. The slope length and LS calculated by LS-TOOLMFD both agreed better with field data than with the calculations using the LS-TOOLSFD and UCA methods, respectively. We then integrated the LS-TOOLMFD algorithm into LS-TOOL developed in Microsoft's .NET environment using C# with a user-friendly interface. The method can automatically calculate slope length, slope steepness, L, S, and LS factor, providing the results as ASCII files that can be easily used in GIS software and erosion models. This study is an important step forward in conducting accurate large-scale erosion evaluation.", "keywords": ["13. Climate action", "LS", "Soil erosion", "0207 environmental engineering", "RUSLE", "Terrain analysis", "02 engineering and technology", "15. Life on land", "GIS", "01 natural sciences", "6. 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The new method, LS-TOOLMFD, was applied and validated in a catchment with complexly variable slopes. The slope length and LS calculated by LS-TOOLMFD both agreed better with field data than with the calculations using the LS-TOOLSFD and UCA methods, respectively. We then integrated the LS-TOOLMFD algorithm into LS-TOOL developed in Microsoft's .NET environment using C# with a user-friendly interface. The method can automatically calculate slope length, slope steepness, L, S, and LS factor, providing the results as ASCII files that can be easily used in GIS software and erosion models. This study is an important step forward in conducting accurate large-scale erosion evaluation.", "keywords": ["13. Climate action", "LS", "Soil erosion", "0207 environmental engineering", "RUSLE", "Terrain analysis", "02 engineering and technology", "15. Life on land", "GIS", "01 natural sciences", "6. 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The proposed integration method based on the topographical features slope line, contour curvature and cutoff factors (ITF method) was used to extract slope length from the raster digital elevation. Slope length extracted using the ITF method had the smallest error in verification of mathematical surfaces (average RRMSE \u00a0=\u00a00.0573), and its spatial distribution was more consistent with the structure of the terrain surface for all test data, relative to the conventional flow direction algorithms in the original DWESL model. The proposed ITF method could provide a reference for predicting soil erosion using the USLE/RUSLE model.", "keywords": ["Slope Length", "Soil erosion", "0211 other engineering and technologies", "0401 agriculture", " forestry", " and fisheries", "RUSLE", "Terrain analysis", "04 agricultural and veterinary sciences", "02 engineering and technology", "15. 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