Chapter 6 - Simulation of Soil Erosion Risk in the Upstream Area of Bo River Watershed

Abstract

Soil erosion has been considered as the primary cause of soil degradation because soil erosion leads to the loss of topsoil and soil organic matter, which are essential for the growing of plants. Quantification of soil loss is a significant issue for soil and water conservation practitioners and policy makers. This chapter presents a comprehensive methodology that integrates the Soil and Water Assessment Tool (SWAT) with a geographical information system (GIS) for simulating soil erosion risk within a small mountainous watershed that is an upstream area of the Bo River watershed in Central Vietnam. The spatial patterns of annual soil erosion rate from 2000 to 2010 were obtained. The results found that the largest amount of soil erosion was 92.33tonha−1 in 2007, followed by 2010 (85.41tonha−1) and 2005 (76.79tonha−1). The average amount of soil erosion from 2000 to 2010 was 62.50tonha−1, which causes high risk in threatening land resource of the whole watershed considerably. Additionally, the resultant maps of annual soil erosion show a maximum soil loss of 153.48tonha–1year–1 with a close relation to dry agriculture land areas on the slopes higher than 25%. The spatial erosion maps generated with SWAT and GIS can serve as effective inputs in deriving strategies for land-use planning and management in the environmentally sensitive mountainous areas.