Estimation of Soil Erosion and Sediment Yield Using GIS at Catchment Scale.pdf

Estimation of Soil Erosion and Sediment Yield Using GIS at Catchment Scale Rabin Bhattarai Dushmata Dutta Received: 5 January 2006 /Accepted: 30 October 2006 / Published online: 12 December 2006 # Springer Science + Business Media B.V. 2006 Abstract A GIS-based method has been applied for the determination of soil erosion and sediment yield in a small watershed in Mun River basin, Thailand. The method involves spatial disintegration of the catchment into homogenous grid cells to capture the catchment heterogeneity. The gross soil erosion in each cell was calculated using Universal Soil Loss Equation (USLE) by carefully determining its various parameters. The concept of sediment delivery ratio is used to route surface erosion from each of the discritized cells to the catchment outlet. The process of sediment delivery from grid cells to the catchment outlet is represented by the topographical characteristics of the cells. The effect of DEM resolution on sediment yield is analyzed using two different resolutions of DEM. The spatial discretization of the catchment and derivation of the physical parameters related to erosion in the cell are performed through GIS techniques. Key words DEM . GIS . soil erosion . sediment delivery ratio . sediment yield 1 Introduction Soil erosion has been accepted as a serious problem arising from agricultural intensification, land degradation and possibly due to global climatic change (Yang et al., 2003). Not only the deposition of sediment transported by river into a reservoir reduces the reservoir capacity, but also sediment deposition on river bed and banks causes widening of flood plains during floods. Soil erosion is the most significant contributor of off-site ground water pollution on a global scale with most of the contaminants originating within an agricultural setting (Marsh and Grossa, 1996). Since it is not possible to monitor the influence of every land-use practices in all ecosystems under all weather conditions, erosion Wa