Vol. 11, Special Issue 9 (2022)

Author(s):
Rizongba Kichu and Manoj Dutta

Abstract:
In the present study, an attempt was made to estimate the average annual soil loss in a small watershed in Nagaland, India, using GIS-based Universal Soil Loss Equation (USLE) technique. Remote sensing data, Digital Elevation Model (DEM), soil and rainfall data were used for determining the USLE parameters. The results showed that R-factor varied from 734.02 and 4157.30 MJ mm ha−1 h−1 year−1. The K-factor ranged from 0.03 to 0.074 t ha h ha−1 MJ−1 mm−1. The LS-factor of the watershed ranged from 0.03 to 54.44. C-factor and P-factor values ranged from 0.07 to 0.53 and 0.28 to 1.0, respectively. The average annual soil loss in Dzumah watershed was found to be 5.38 t ha−1 year−1, which is less than the permissible soil loss limit recommended for Himalayan regions. It was also observed that almost 90% of the watershed area was under light and moderate erosion classes with each class occupying 1777.34 and 4089.67 ha, respectively. Based on the findings, it was inferred that the watershed is stable with no major risks of erosion. The stability of the watershed despite its rugged terrain could be due to the excellent forest cover in the steep sloped higher reaches of the watershed. Furthermore, given the fragile mountainous environment of the watershed, it is significantly important to conserve the existing forest cover and adopting appropriate soil conservation measures to any changes in the land use for sustaining the stability of the watershed.