Assessment of soil erosion, flood risk and groundwater potential of Dhanari watershed using remote sensing and geographic information system, district Uttarkashi, Uttarakhand, India

Abstract

AbstractQuantitative morphometric analysis of Dhanari watershed has been done using remote sensing and Geographical Information System (GIS). The impact of climate, lithology, tectonics, structural antecedents, vegetation cover and land use on hydrological processes is assessed by quantifying geomorphic parameters. The Dhanari River (a tributary of the Bhagirathi River) and its tributaries Dhanpati Gad and Kali Gad forms Dhanari watershed covering 91.8  Km2 area. Several geomorphic aspects viz. linear, areal, relief were computed to comprehend potentials of soil erosion, groundwater, flood vulnerability and the geomorphic response of watershed. LISS-III image is used to generate the Land Use and Land Cover (LULC) map and assess the watershed dynamics. Values of computed hypsometric integral and morphometric parameters viz. drainage density ($$D_{{\text{d}}}$$ D d ), stream frequency ($$F_{{\text{s}}}$$ F s ), stream length ratio ($$L_{{{\text{ur}}}}$$ L ur ), bifurcation ratio ($$R_{{\text{b}}}$$ R b ), rho coefficient (ρ), drainage texture ($$D_{{\text{t}}}$$ D t ), circularity ratio ($$R_{{\text{c}}}$$ R c ), relief ratio ($$R_{{{\text{hl}}}}$$ R hl ), elongation ratio ($$R_{{\text{e}}}$$ R e ), form factor ($$F_{{\text{f}}}$$ F f ), basin shape ($$B_{{\text{s}}}$$ B s ), drainage intensity ($$D_{{\text{i}}}$$ D i ), compactness coefficient ($$C_{{\text{c}}}$$ C c ) and infiltration number ($$I_{{\text{f}}}$$ I f ) have shown a moderate and steady erosion rate, with low groundwater potential and low to moderate flood vulnerability in the watershed. Hypsometry presents a dependable geomorphic parameter to understand the erosion and geomorphic response of a watershed to hydrological processes. Hypsometric integral value (0.51) of Dhanari watershed suggests a mature topography with steady erosion in the watershed.