SOIL EROSION MODELLING USING REMOTE SENSING AND GIS FOR NAGALAND

Abstract

Soil erosion in mountain areas like Nagaland is a matter of concern as it not only results in the loss of fertile topsoil but also has its off-side effects on environment as it threatens natural resources, agriculture and the environment. In this study, estimation of soil loss for Kohima district of the State Nagaland has been carried out using Universal Soil Loss Equation (USLE), remote sensing data and Geographical Information Systems (GIS). The SRTM DEM was used to generate slope map. Other inputs of the model closely related to the land use/land cover were successfully derived from remotely sensed data and the modeling part was carried out in GIS environment. Annual average soil loss of thirty years from 1981 to 2010 was estimated for the study area. Based on 30 years rainfall data, the average annual soil loss was 109.16 t ha-1yr-1. Maximum value of soil loss was 194.600 t ha-1yr-1 in 1992, the year of highest rainfall (2579.1 mm). The lowest value of soil loss was 49.09 ha-1yr-1 in 1997, the year of lowest rainfall when rainfall was only 1242.2 m. Finally, critical soil erosion prone areas were identified. It was observed that soil erosion is highly variable in the spatial as well temporal domain; therefore, soil loss does not occur in a uniform manner in each landscape level. In the study area 3.4 percent under falls under slight erosion class, 18.42 percent under moderate erosion class, 56.34 percent (754.39 km2) of the total area falls under high erosion class, 0.01 percent under severe erosion class and 21.83 percent falls under very severe erosion class. The areas falling under high and very severe erosion class requires immediate attention from soil conservation point of view.