Assessment of Soil Erosion Prone Zonation using the RUSLE Model in the Upper Ponnaiyar River Basin, Southern India

Soil is the most important of all our natural resources. The erosion process reduces soil fertility and drastically affects agricultural practices. In this context, Revised Universal Soil Loss Equation (RUSLE) has been adopted to estimate soil erosion in the Upper Ponnaiyar River Basin, Tamil Nadu, India, using remote sensing and GIS technology. This model takes into consideration various parameters including runoff-rainfall erosivity factor (R), soil erodability factor (K), topographic factor (LS), cropping management factor (C), and support practice factor (P). The results of the study indicate that the annual average soil loss within the watershed for forest and barren land is about 7 t/ha/yr (metric ton per hectare per year). Higher soil erosion is observed in the land use classes of gullied wasteland, open scrub forest and degraded plantation. The soil erosion risk is considerably higher on the steep slopes and adjoining foothills. Based on the average soil erosion values of different land use classes and characteristics of land, a proposed land use map has been prepared. The average annual soil loss map will be highly useful in identifying the priority areas for implementation of sustainable land use practices and soil conservation measures in the Upper Ponnaiyar River Basin. It is understood that functions of C and P are factors that can be controlled and thus can greatly reduce soil loss through management and conservation measures. The estimated soil erosion and the proposed land use map could be an effective input for drawing up sustainable watershed development measures. The mean annual soil loss for the entire study area is about 28.26 tons/ha/yr. the average annual soil loss map will be highly useful in identifying the priority areas for implementation of sustainable land use practices and soil conservation measures in the Upper Ponnaiyar River Basin. When improper cultivation methods are followed and the land is ploughed, that area loses a great deal of topsoil during the windy and rainy seasons.