Abstract:
The investigation of basins for planning soil conservation requires a
selective approach to identify smaller hydrological units, which would be suitable for
more efficient and targeted conservation management programmes. One criterion,
generally used to determine the vulnerability of catchments to erosion, is the sediment
yield of a basin. In India, sediment yield data are generally not collected for smaller
sub-catchments and it becomes difficult to identify the most vulnerable areas for
erosion that can be treated on a priority basis. An index-based approach, based on the
surface factors mainly responsible for soil erosion, is suggested in this study. These
factors include soil type, vegetation, slope and various catchment properties such as
drainage density, form factor, etc. The method is illustrated with a case study of subcatchments
immediately upstream of the Ukai Reservoir located on the River Tapi in
Gujarat State, India. The area is divided into 16 watersheds and different soil,
vegetation, topography and morphology-related parameters are estimated separately
for each watershed. Satellite data are used to evaluate the soil and vegetation indices,
while a G1S system is used to evaluate the topography and morphology-related
indices. The integrated effect of all the parameters is evaluated to find different areas
vulnerable to soil erosion. Two watersheds were identified as being most susceptible
to soil erosion. Based on the integrated index, a priority rating of the watersheds for
soil conservation planning is recommended.
