Spatial and Temporal Variation of C– Factor and Soil Erosion in a Semi-Arid Watershed: A Case Study in Mahabubnagar District

Abstract

Identifying the erosion prone areas and estimation of soil loss in the watershed is essential for implementing suitable conservation practices. In the present study, spatial, temporal variation of C-factor and soil erosion was assessed in a micro-watershed, located in Mahabubnagar district using RUSLE, integrated with Remote Sensing and GIS for the period 2001 to 2016. The mean annual erosivity factor (5007.56 MJ mm ha−1 h−1 yr−1) was derived using daily rainfall data, by adopting standard procedures. The soil erodibility (K) and conservation practice (P) factors in the study area were selected as 0.017 and 0.39, based on watershed geological features. The cover management factor (C) was derived from the MODIS NDVI images of 16 day interval, with 250 m resolution. The results indicated that, the values of the C factor ranged from 0.01 to 0.85 and varied spatially and temporally, depending upon variation in the vegetative cover. The areas having lower NDVI, resulted in higher values of C factor. No considerable variation in mean C factor was observed, during above normal, normal and drought years. The annual soil loss varied spatially from 0.0016 to 15.68 t ha−1 yr−1and mean annual soil erosion of 1.27 t ha−1 yr−1. And the mean annual soil loss was found to be 2.0, 1.16 and 0.69 t ha−1 yr−1 during above normal, normal and drought years. The obtained results inferred that, major portion of the study area comes under slight erosion category (< 2.5 t ha−1 yr−1) and in-situ soil conservation measures (strip cropping, crop rotations, etc.), farm ponds and percolation tanks are recommended for the sustainable management of watersheds.