Raster Grid Based Assessment of Soil Erosion using USLE and Geospatial Technology to Identify Critical Zone: A Case Study of Chaka Watershed, West Bengal, India

Abstract

Soil erosion, an important environmental challenge, exerts a notable influence on land quality and productivity affecting food security at all level from local to global. In India, the prevalence of soil erosion covers about 120.7 hectares area with an average annual soil loss of 16.35 tonnes per hectare (ICAR and NAAS, 2010). Assessment and identification of spatial pattern of soil erosion are essential prerequisites for sustainable management. The estimation of soil loss has been attempted integrating USLE (Universal Soil Loss Estimation) with Geospatial Technology. The present study aims to estimate soil erosion in Chaka Watershed of Purulia district, West Bengal, India. The study also assessed relative influence of factors involved in soil erosion. Six erosion classes were derived for the watershed out of which four classes were identified as critical zones covering about 44.39% area with a soil loss ranging from 10 to more than 80 tonnes hac^-1 year^-1. The study reveals 19.61% area is under high erosion (10-20 tonnes hac^-1 yr^-1), 14.92% area is under very high erosion (20-40 tonnes hac^-1yr^-1), 7.73% is under severe erosion (40-80 tonnes hac^-1 yr^-1) and 2.13% area is under very severe erosion (>80 tonnes hac^-1 yr^-1). Result of multiple linear Regression analysis shows significance of factors influencing soil erosion. It is revealed that slope length and steepness factor has highest influence followed by cover and management factor, soil erodibility factor, support practice factor and rainfall erosivity factor.

The severity of erosion in conjunction with diverse factors facilitates a comprehensive understanding of spatial distribution of soil erosion within the watershed. This information will be helpful for immediate intervention of the authority with active participation of the stakeholders to implement site-specific programmes and effective soil conservation practices, as well as tailor-made land use plans specifically designed for critical areas prone to severe erosion.