Down-scaling method for transformation of national soil maps into spatially distributed values of soil erodibility factor according to terrain morphology using GIS tools

With the current advancements in GIS and remote sensing methods, especially the use of high-precision LiDAR data, there is a significant disparity in the accuracy of morphological and soil data in erosion assessment. In current practice, a soil geospatial database is used to determine erodibility (K factor), often causing step changes in value within a field. However, soil properties influencing the K factor typically vary smoothly with terrain morphology and the soil catena pattern. Terrain morphology should therefore be taken into account, and it will lead to a more precise spatial distribution of K-factor values, significantly refining soil loss calculations and erosion control planning. For this purpose, the Czech Soil-Morphological Geospatial Database containing 1,417 soil samples was created. All soil samples were analyzed in the laboratory, and their K values were linked to morphometric characteristics (MMCH) based on geographical coordinates. The correlation dependences of the MMCH and spatial changes of K values, as deviations from the average values for the drainage areas within the closed erosion units, were calculated. The results of the methodology validation show a statistically high significant dependence between the K values obtained from field measurements and the values generated by the K-terrain model, created to automate the calculation. The tool can be used for down-scaling of K factor maps of large areas according to digital terrain model. To allow it to be applied more effectively to land management, a map with K terrain values for the entire Czech Republic was created with a resolution of 10 m.