Evaluation of Soil Erosion Risk in the City of Cobija, Bolivian Amazonia Using RUSLE and GIS

Abstract

In recent years, deforestation has increased remarkably in the region of Bolivian Amazonia. So, research interests have been focused on how the deforestation affects the soil erosion risk. Accordingly, this study was conducted in the city of Cobija, Bolivian Amazonia to evaluate the erosion risk employing the Revised Universal Soil Loss Equation (RUSLE). For calculating the rainfall-runoff erosivity factor (R), an emperical model based on measured annual precipitation was applied. To calculate the soil erodibility factor (K), the experimental models based on soil properties (composition of sand-silt-clay percentages, organic matter, structure, and permeability of the soil profile) was employed. Also, to generate the topographic factor (LS), a digital elevation model (DEM) image was applied. In addition, the cover management factor (C) of each land use and the support practice factor (P) for different conservation practices were based on the outcomes from former studies. The results of RUSLE analysis, the annual soil loss per unit area (A) was in the range of of the medium soil loss from 5 < 7 t/ha/year. With accelerating soil erosion, soil organic matters as well as soil aggregate have been lost, and soil loss would be severer gradually. So, effective soil conservation measures should be implemented for minimizing the loss of soil organic matters as well as soil aggregate.