REVISED UNIVERSAL SOIL LOSS EQUATION (RUSLE) MODEL IN THE BÂSCA CHIOJDULUI RIVER BASIN (SUBCARPATHIANS, ROMANIA)

Soil erosion is one of the most significant issues around the world. In addition to the direct harmful effect on the soil itself, which reduces agricultural productivity, soil erosion impacts socioeconomic factors and the flow of sediments in riverbeds. It is exacerbated by human activities, particularly on land use, in correlation with the current global climate change. The goal of this research is to determine the amount of eroded soil in the Bâsca Chiojdului hydrographic basin that is further transported downstream and settles in riverbeds contributing to solid flow. The achieve the goal, the RUSLE soil erosion model, widely used in the literature was implemented. The RUSLE model is widely used in studies of soil erosion around the world. It was based on the previous USLE model and takes into account five factors that influence erosion: rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), land cover and management (C), and supporting practice (P). In the current paper, the K Factor is calculated using a global database provided by the World Soil Information System and it takes into account the percentage fraction of sand, silt, clay, and organic matter in the soil. The LS Factor considers the configuration of the slopes on which the torrential runoff regime depends, and it is computed using the USPED method and a DEM with a resolution of 10 meters to improve accuracy. The R Factor represents the regime of liquid precipitation that has the capacity to displace particles of soil, and it was calculated using multi-year precipitation data for the period 1961-2000. The C Factor is estimated using NDVI calculated seasonally rather than relying on a single image date. This seasonal approach provides a more accurate representation of vegetation cover dynamics throughout the year, allowing for a detailed analysis of seasonal variations in soil loss and their direct influence on sediment transport processes. Overall, the maximum soil erosion rates reach the amount of 45 tonnes per year. The areas with the highest erosion rates in the basin have also high LS and CP factors, and overlap with deforested areas. Significant levels of erosion occur in areas with clays, marls and sandstones in the substrate.