Prioritizing erosion-prone areas in hills using remote sensing and GIS — a case study of the Sukhna Lake catchment, Northern India

Abstract Traditionally, assessment of productivity of land took priority over all other aspects of evaluating land use performance. Presently, the effects of land use on the quality of the environment and environmental sustainability of production systems have become the major issues. In hills, the terrain conditions aggravate erosion-induced land degradation. Judicious allocation of available resources for sustainable production requires mapping, monitoring and prioritizing the areas based on their susceptibility to degradation. Remote sensing and Geographic Information Systems are effective tools for inventory, monitoring and management of spatially distributed resources. This paper presents a case study of the 42 km 2 Sukhna Lake catchment in the Shiwalik hills conducted for the delineation and prioritization of erosion-prone areas using RS and Geographic Information Systems. Multi-spectral IRS ID-LISS III data acquired in March 1998 was used for the supervised digital classification of the land use/land cover type. The catchment was classified in six land use classes: forest, agriculture, scrub, barren hills, streambed and settlements. These classes were divided into sub-classes based on the cover characteristics. Using the U.S. Soil Conservation Service curve number method, runoff potential of each delineated hydrologic unit was computed in a grid-based analysis using an ARC/INFO GIS. Erosion-prone areas were classified further by integration of a digital elevation model or DEM-derived slope, aspect and flow length. To get an ordered priority of the erosion-prone areas, a cumulative erosion index was computed from the rating given to the three main causative factors, ie , slope, soil erodibility, and land cover, on a scale of 1–7 for each grid. The cumulative index was further classified in four classes for spatial representation of the erosion-prone areas on the catchment map. The study revealed that 32.9 percent of the catchment area is susceptible to high or very high erosion risk and thus has to be managed with appropriate conservation strategies.