Development of a GIS tool for evaluating the spatio-temporal variability of the soil erodibility factor throughout the year: A case study of the Czech Republic

The soil erodibility factor (K) exhibits significant spatio-temporal variability depending on geographical location, influenced not only by varying soil characteristics but also by climatic factors. This study presents the development and validation of a geographic information system (GIS) tool, the spatio-temporal distributed (STD)-K factor, designed to calculate monthly K values using high-resolution, fully distributed raster inputs. The primary input is a standard map of the annual K values, which the GIS model transforms into monthly K values based on the temporal distribution of climatic parameters throughout the year. These climatic inputs include rainfall conditions—specifically, average annual and monthly rainfall erosivity factor values (R) and temperature-related factors such as the length of the growing season and the beginning and end of the frost-free period. The tool was validated using 120 soil samples from 20 locations. Correlation and regression analyses comparing measured and modeled K values showed strong agreement, with correlation coefficients of r = 0.89 (R² = 0.79, p < 0.0001). Standard maps of the annual K factor can be refined using this approach, enabling the calculation of corrected annual and monthly K values. Monthly K factor maps can support detailed assessments of erosion risk throughout the year, facilitating improved crop rotation planning and the design of erosion control measures.