Application of geospatial techniques in morphometric analysis of sub-watersheds of Nanak Sagar Catchment

The present study highlights the effectiveness and advantages of remote sensing and Geographic Information System (GIS)-based morphometric analysis for quantitative and qualitative assessment of Nanak Sagar catchment, Uttarakhand. For mapping remotely sensed data, GIS have been proven to be the most powerful advanced technology. The fundamental areal, linear and relief aspects of morphometric analysis were calculated after processing the DEM (Digital Elevation Model) in GIS software. The entire catchment area was divided into 13 sub-watersheds and 21 morphometric parameters were calculated for each one of them. SRTM-DEM was used in the analysis, to extract the drainage network as well as various thematic maps. Stream order (Nu), stream length (Lu), mean bifurcation ratio (Rbm), drainage density (Dd), length of overland flow (Lg), basin length (BL), circulatory ratio (Cr), elongation ratio (Re), form factor (Ff), shape factor (Sf), infiltration number (In), stream frequency (Stf), relief (R), relief ratio (Rh), ruggedness number (Rn) were the parameters considered. With the total area of 407.20 km2, drainage basin was found of having dendritic nature, and is classified as 6th order basin. SW7 is more vulnerable to erosion than other subwatersheds, with high values of In, Stf, and Dt and should be consider for planning and management followed by SW6 and SW5. Overall analysis shows that reservoir have nearly fewer structure wise disturbances as Dd values lies between 3 to 6 and elongated shape of all sub-watersheds shows minimum runoff potential but increased yield of sediment load due to high infiltration numbers and relief.