Physiographic Study of Mandakini valley (Rudraprayag District) Garhwal Himalaya by Morphometric Analysis and Geospatial Techniques

Physiographic unit Mandakini basin with Rudraprayag district administrative are is covering area about 1982.93sq. Km (Latitude 30⁰19’00’’ and 30⁰49’ North and longitude 78049’ and 79⁰ 21’ 13’’ East) lies in Garhwal Himalayan Range, India has been selected for physiographic study through morphometric analysis. The basic aim of present study is to elucidate the characteristics of the areal, linear and relief features of the area using SOI toposheets and ASTR DEM which contribute as dominant factor to assess the landscape features of basin. It revealed that the Mandakini basin has seventh order river network with dendritic pattern suggests the different homogeneous geological attributes, moderate to steep slope and strong structural control. Bifurcation ratio between different successive orders varies very few but mean ratio indicates that the strong structural control and less permeability of rocks. Moderate to moderate course drainage density, moderate to moderate high drainage frequency and very high texture ratio suggests that terrain has steep slopes, complex deformed lithology. Geometric parameters indicates that the basin is less elongated in shape with moderate to very high relief, less infiltration capacity and longer duration of water flow in the basin. The minimum absolute relief 794.94 m. is in the southern part and the maximum 6993.71 m. in the northern upper part and moderate to very high sloping of the basin. The all morphometric indicators and existing landforms indicate youth stage of topography of the basin.