GIS-Based Morphometric Analysis of the Eastern Nayar Watershed, Uttarakhand, India

Morphometric analysis provides a quantitative framework for understanding the drainage characteristics, geomorphic evolution, and hydrological response of a watershed. The present study evaluates the morphometric parameters of the Eastern Nayar watershed, located in the Lesser Himalayan region of Uttarakhand, India, using Geographic Information Systems (GIS) and Digital Elevation Model (DEM)-based techniques. A CartoSat-1 DEM was used to delineate the watershed and extract the drainage network using a stream initiation threshold of 600, and stream ordering was carried out following the Strahler method. The watershed is identified as a fifth-order basin comprising 933 stream segments with a total stream length of 910 km. Linear morphometric analysis shows a systematic decrease in stream number with increasing order, consistent with Horton’s law, while the mean bifurcation ratio (1.83) suggests limited structural control over drainage development. Areal parameters indicate a drainage density of 0.90 km/km² and stream frequency of 0.92 streams/km², reflecting moderate drainage development and infiltration capacity. The basin exhibits an elongated shape, as indicated by a low form factor (0.03) and elongation ratio (0.28), implying reduced peak discharge and prolonged runoff duration. Relief analysis reveals high basin relief (2548.64 m) and a ruggedness number of 2.29, indicating steep terrain and significant erosion potential. Slope and aspect analyses further highlight terrain variability and its influence on hydrological processes