Impact of land-use change on soil erosion in the Coonoor watershed, Nilgiris mountain range, Tamil Nadu, India

Abstract

Over the past several decades, the conversion of native forest to tea plantation and crop land has accelerated across the Coonoor watershed in Nilgiris. It is notable that the present study explored the severity prevalent in the land cover changes including deforestation activities at Coonoor watershed region as a result of urbanization, recreation parks, resorts and tea plantation development. The Revised Universal Soil Loss Equation (RUSLE) is one of the most widely used soil erosion model which estimates the average soil loss over a long-term period. This paper therefore, imprinted the impact of land use changes on land degradation and the consequent vital phenomenon like the soil erosion. The change detection was carried out between the periods of 2005-2018. Landsat images of corresponding periods were classified using supervised classification technique and also Normalized Differential Vegetation Index (NDVI) was computed for the determination of C-factor (cover and management factor) for the corresponding periods. Conversion of forest land into tea plantation, wasteland and settlement significantly decreases the soil organic matter (SOM) and hydraulic conductivity (HC) of the soil, which leads to different K-factor (soil erodibility factor) for the study duration, whereas the R-factor (rainfall and runoff factor) and LS-factor (length-slope factor) are considered to be constant throughout the period. The results of this study indicates via promising results, that the total sediment yield of the study area has remarkably increased due to land use/cover changes. The most significant rise in soil erosion was found evitable in the deforested region where there has occurred a changeover from forest/orchard to infrastructure and wasteland.