Evaluation soil erosion risk in mountain catchment by two empirical models

Productive capacity of soils is seriously affected by erosion, causing significant environmental damages. Soil erosion led to instability in ecosystems and decline in agriculture productivity as well as in forest territories. The negative anticipation about climate hesitation for acceleration soil erosion shows the need for monitoring the condition of the soils and taking adequate measures to reduce the risk. For that reason, different models for assessing soil erosion risk and determining potential levels of erosion are strongly advocated in researches. Two of the well-known and commonly used empirical models for the territory of Balkans are Erosion Potential Method (EPM) and Universal Soil Loss Equation (USLE). The objective of the research is to apply EPM and USLE models at the Sedelska River watershed, tributary of Struma River (Southwest Bulgaria), to assess soil erosion risk and investigate its spatial distribution. The results of the two methods are compared, finding that the EPM method slightly underestimates the final results compared to the USLE methodology. In both models, the territories with the strongest erosion risk were determined, and some of them coincide. When applying the USLE, it was found that the largest area of the research site is occupied by the lands on which a low actual risk is observed (47.10%). From the results obtained when applying the EPM, the watershed falls into the third degree of the Gavrilovich scale - a watershed with moderate erosion. The average amount of soil eroded assess with EPM is 3 t/ha/y. According to USLE the average potential risk with amounts of eroded soil of 100-200 t/ha y.