No abstract

In the present paper, various morphological parameters representing one dimensional view via linear, two dimensional view via a real and three dimensional view via relief aspect of the catchment have been extracted in GIS environment by partitioning a Western Himalayan catchment from the Indian subcontinent into eight sub-watersheds (SW1 to SW8). The study catchment was found to be a sixth order drainage basin as per the Strahler stream ordering scheme. The catchment is dominated by the parallel and dendritic drainage patterns in different sub-watersheds. Higher bifurcation ratios between the first and second order streams imply the presence of active gullies in the catchment. Medium to high drainage densities, ranging 2.64 to 4.08 were found in the study area indicating the weak or impermeable subsurface material, high mountainous relief and fine drainage texture. Most of the sub-watersheds are characterized with high relief ratio, relative relief and average slope which are favorable to generate significant runoff even for a small volume of rainfall. In order to prioritize the catchment, a compound index was calculated by considering the individual rank assigned to all eight sub-watersheds based on 13 morphological parameters. To decide the quantum of conservation work required in each sub-watershed, the quantitative assessment of soil loss has been done using sediment production rate (SPR).Sediment production rate (SPR) of all sub-watersheds varies between 1.18 ha-m/100 sq.km/yr to 3.96 ha-m/100 sq.km/yr. These values are in concurrence with the design SPR values as adopted in most of the river valley projects constructed in the Western Himalayan region of India. SPR values estimated as well as compound ranking evaluated using morphological parameters in the present study may be helpful in identifying the critical areas in a ungauged catchment and accordingly deciding the watershed treatment measures in volume and space.