CS(AR)-14/99-2000 : Watershed prioritisation of Ukai dam catchment using remote sensing and GIS

Abstract

Investigation of basins for conservation planning is quite cumbersome and expensive. Therefore, it requires a selective approach to identify smaller hydrological units, which would be suitable for more efficient and targeted resource management programs. The identification of these critical sub-basins, which need soil and water conservation measures on preferential basis, is particularly important in the areas that are close to a reservoir. A criterion, which can be used to determine priority for conservation planning, may be the soil erosion or sediment yield of a basin.

In the present study, watershed prioritization of the catchment immediately upstream of the Ukai reservoir has been carried out using remote sensing technique. For this purpose, Watershed Response Model (WRM) has been used. This model utilizes the Normalized Difference Vegetation Index (NMI) and the Soil Brightness Index (SBI), the two important parameters responsible for soil erosion. In this study, these two parameters have been determined using remote sensing data. ERDAS IMAGINE system has been used for carrying out the digital image analysis. The other two parameters, i.e. morphological and topographical have also been considered and ILWIS system has been used for their estimation. The immediately contributing catchment upstream of the Ukai reservoir has been divided into 16 watersheds and different vegetation, soil, topography and morphology related parameters have been estimated for all the watersheds separately. The integrated effect of all the parameters has been evaluated to recommend the priority rating of the watersheds for conservation planning.