SOIL EROSION MODELLING IN THE COMPLEX TERRAIN OF PIROT MUNICIPALITY

This paper aims at assessment of soil erosion potential and its spatial distribution on the 1235 km(2) area of municipality Pirot located in south-eastern Serbia. The study was conducted by using well-known Universal Soil Loss Equation (USLE) model due to its modest data demand and transparent structure. The erosion factors of USLE were collected and processed through a GIS-based approach offering ease of elaboration and manipulation of erosive factors. All the erosive factors were determined on a 30 x 30 m cell basis and multiplied in order to obtain the map of potential average annual soil erosion. The average annual soil loss was estimated at 8.65 tha(-1)yr(-1) classifying the area of Pirot municipality under low erosion rate category. More than 80% of the municipality area was characterized by insignificant (< 3 tha(-1)yr(-1)), and low erosion category (3-10 tha(-1)yr(-1)). Around 7.8% of the area was found to be under moderate erosion category (10-20 tha(-1)yr(-1)). High erosion category was found on 6.8% of the area (20-40 tha(-1) yr(-1)), while there is around 5.2% of the area under very high erosion category (>40 tha(-1)yr(-1)). It means that almost 15000 ha of the area of Pirot municipality are facing high and very high erosion. The analysis of vertical distribution of erosion processes pointed out that the zone between 500 and 800 m a.s.l suffers more from erosion than other elevation zones mainly due to land management. The results of this work are in agreement with the soil erosion map of Serbia, the sediment yield measurements in the basin and with other, more detailed, studies in the municipality. Therefore, the presented methodology could be applied as a framework for the evaluation of erosive factors on soil resources in Serbia when limited data are available. The outputs of these studies can be used for the identification of vulnerable areas on a cell-basis and for programming of protection measures.