Updating the digital layer of R-factor (USLE rainfall erosivity factor) for the territory of Slovakia

The updated version of USLE erosion prediction model is still an indispensable tool to evaluate the water erosion for the needs of soil conservation due to its simplicity and relative availability of input parameters. The primary objective of this study was to improve the data on R-factor for the territory of Slovakia. This involved two tasks: a) updating the values of rainfall erosivity factor (R-factor) for individual automatic meteorological stations based on one-minute rainfall totals, b) generating the digital layer of R-factor spatial distribution across the entire territory of Slovakia. In 2009 the digital layer of R-factor was created for the USLE model presented on Soil Portal of VUPOP. The previous digital layer of R-factor was based on values calculated by Malíšek (1990, 1992). However, these values are not representative anymore as the medium-term and long-term temporal rainfall dynamics resulted in changing the rainfall means and their spatial distribution patterns during the last few decades. The new calculation of R-Factor was done using a rainfall database of 85 automatic rainfall stations provided by Slovak Hydrometeorological Institute. The resulting updated mean annual R-factor values ranging from 33,55 MJ.ha−1.cm.h−1 (Malacky) to 160,91 MJ.ha−1.cm.h−1 (Runina, Snina district) were used to generate a new digital layer of rain factor spatial distribution for the whole territory of Slovakia. This digital layer will be an essential input component for the USLE erosion prediction model. It will significantly improve the soil erosion rate estimates generated by USLE model in Slovakia and this will contribute to improving the background information used for supporting soil erosion assessment and soil conservation programs.