Analysis of Watershed Characteristics Using Remote Sensing and GIS Techniques

2 ABSTRACT: Watershed is a natural hydrological entity which allows surface run-off to a defined channel, drainage, stream or river at a particular point. It is the basic unit of water supply, which evolves over time. Morphometric analysis is a quantitative description and analysis of landforms as practiced in geomorphology that applied to a particular kind of landform or to drainage basins. Remote sensing (RS), Geographical Information System (GIS) has proved to be an efficient tool in delineation of drainage pattern and water resources management and its planning. In the present study, GIS and image processing techniques have been adopted for the identification of morphological features and analysing their properties of the Eru river Basin, sub watershed of Mahi river, Rajasthan, India. The basin morphometric parameters such as linear and aerial aspects of the river basin were determined and computed. The study area covers 71.40 km 2 comprising of 3 sub-watersheds. The drainage network of 3 sub-watersheds was delineated using Landsat ETM remote sensing data and standard Survey of India topographical maps on 1:50,000 scale. The drainage network shows that the terrain exhibits dendritic to sub-dendritic drainage pattern. The highest stream order is fourth order. Estimated drainage density is approximately 1.82 and has very coarse to coarse drainage texture. The mean bifurcation ratio is 3.70 that indicate uniform geological structure and lithologies in watershed area. The investigation has shown that as the order of stream increases total length of stream segments is decreases. Hence, it can be concluded that there is a relationship between stream numbers and stream lengths as per the Hortons law of stream length. The elongation ratio shows that Eru river sub-watershed possesses elongated shape pattern. The study showed that GIS techniques proved to be a competent tool in morphometric analysis.