DETERMINATION OF EROSION INTENSITY IN BRKA WATERSHED, BOSNIA AND HERZEGOVINA

The Bosnia and Herzegovina (BiH) erosion map was made in 1985, however, over a period of 35 years, there has been a substantial change in the values of most erosion factors, resulting in the change of the erosion intensity. Changes relate to demographics, urbanization and land use as well as climate. The increase in temperature and the occurrence of extremes caused significant environmental and economic consequences (May 2014 floods). This situation is more pronounced in the northern part of the country, especially in the lower parts of the larger basins. Risk assessment procedures using modern software and hardware solutions can help decision-makers to recognize sites where forest should not be cut down, certain crops should not be grown or soil conversation measures are necessary. Therefore, the aim of this research is to estimate the intensity of erosion processes in one such watershed in BiH the Brka watershed, taking into consideration current conditions and using modern hardware and software solutions. To calculate erosion intensity the Gavrilovic method supported with GIS techniques was used. The soil protection (x), soil erodibility (y) and type and extent of erosion (φ) coefficients were calculated using digital maps: CORINE 2018 (grid size 100 m x 100 m) land cover, soil map of BiH and open-source satellite images. The slope was calculated from the BiH digital elevation model (25 m x 25 m). The Brka watershed area (184.09 km 2 ) was divided into four basins: Maočka Rijeka (51.56 km 2 ), Rahička Rijeka (24.26 km 2 ), Zovičica (75.30 km 2 ) and direct basin of Brka (32.94 km 2 ). The highest average erosion intensity was determined for Zovičica basin, where Z=0.56. The calculated mean annual production of sediment per basin varies from 5,746 for Rahička Rijeka to 57,089 m 3 year -1 for Zovičica, with total Brka river watershed sediment yield of 120,754 m 3 year -1 .