Recent Research in Science and Technology 2011, 3(3): 51-57 ISSN: 2076-5061 www.recent-science.com GEOLOGY AND GEOGRAPHY INTEGRATION OF GIS AND UNIVERSAL SOIL LOSS EQUATION (USLE) FOR SOIL LOSS ESTIMATION IN A HIMALAYAN WATERSHED Ashaq Hussain Sheikh¹ ∗ , Sarvesh Palria 2 and Akhtar Alam 3 ¹Department of Geology and Geophysics, University of Kashmir, Srinagar, J&K, India 2 Department of Remote Sensing and Geoinformatics, M.D.S. University of Ajmer, Rajasthan, India 3 Department of Geography and Regional Development, University of Kashmir, Srinagar, J&K, India Abstract In order to assess soil erosion at watershed scale Universal Soil Loss Equation (USLE) erosion model has been used on IEL7 watershed of Lidder Catchment in Himalayan Region. Erosion calculation requires huge amount of information and data, usually coming from different sources and available in different formats and scales. Therefore GIS was used, which helped considerably in organizing the spatial data representing the effects of each factor affecting soil erosion. The factors that most influence soil erosion are linked to topography, vegetation type, soil properties and land use/cover. Average annual soil losses were calculated by multiplying five factors: R; the erosivity factor, K; the soil erodibility factor; LS, the topographic factor; C, the crop management factor and P; the conservation support practice. The annual soil loss predictions range between 0 and 61tons ha -1 . Average soil loss was highest (26 tons ha -1 year -1 ) in agriculture area and lowest soil loss rate was found in forest area (0.99 tons ha -1 year -1 ). For horticulture and plantation the soil loss rates were 1.47 and 5.39 tons ha -1 year -1 respectively. For pasture, fallow and scrub the soil loss rates were 25.47, 28.39 and 35.76 tons ha -1 year -1 respectively. Keywords: Estimation, GIS, Loss, Soil, USLE, Watershed ∗ Corresponding Author, Email: s_ashiqin@yahoo.co.in Introduction Universal Soil Loss Equation (USLE) is the most popular empirically based model used globally for erosion prediction and control (Laflen, 2002; Kesley, 2002). Scientifically, the main attributor to land degradation is soil erosion by runoff water (Angima et al., 2003). Of the world's land degradation problems, soil erosion is the first order category (Hitzhusen, 1993). Soil erosion by water is a major problem in mountainous areas with steep slopes. Inappropriate land use in these areas is likely to accelerate water erosion entailing soil loss and land fertility decline (Hurni et al., 1996; Liniger and Thomas, 1998). Suspension from the eroded material damages the water quality in downstream areas and its subsequent sedimentation decreases the carrying capacity of water bodies. Therefore, controlling erosion is crucial to sustain agricultural yields and to reduce environmental damage. Spatial and quantitative information on soil erosion on a regional scale contributes to conservation planning, erosion control and management of the environment. Identification of erosion prone areas and quantitative estimation of soil loss rates with sufficient accuracy are of extreme importance for designing and implementing appropriate erosion control or soil and water conservation practices (Shi et al., 2004). Equally, erosion and sedimentation research and a proper understanding of the physical processes are important in order to enhance understanding of landform development across temporal and spatial scales (Slattery et al., 2002; Wainwright et al., 2003). Remote sensing and GIS techniques have become valuable tools specially when assessing erosion at larger scales due to the amount of data needed and the greater area coverage. For this reason use of these techniques have been widely adopted and currently there are several studies that show the potential of remote sensing techniques integrated with GIS in soil erosion mapping (Pilesjo, 1992; Metternicht and Fermont, 1998). Study area location IEL 7 watershed, located in lower Himalayas, India, is a mountainous watershed with steep slopes and complex relief (Figure 1). The selected watershed (IEL 7) occupies an area of 113 km -2 , and about half of the study area consists of high mountains with elevations more than 3500 m. The elevation ranges from 1663 m to 4,226 m above mean sea level.