Morphometric analysis of Diyung watershed in northeast India using GIS technique for flood management

The North eastern region is characterized by undulating terrain and high rainfall. Such condition creates a situation of floods in the downstream plain areas of Assam. Difficulties in monitoring the data collection of hydrological events (runoff and sediment yield) in the rugged terrain hinders the planning of suitable control measures. To overcome such constraints alternate measures need to be explored and the study of terrain is one such approach. The study of terrain (morphometry) can help in diagnosing the hydrological behavior of any watershed. In the present study morphometric analysis was done to determine the drainage characteristics of Diyung watershed in Kopili river basin using topographic maps and GIS tools. The morphometric analysis indicates high values of stream density (15464), stream length ratio (1.81); Bifurcation ratio (3.66), RHO coefficient (0.49), Stream frequency (5.26 km-2), Drainage density (3.24), indicative of high runoff generation capabilities of the watershed. This high runoff from the watershed is the main reason for floods in the downstream areas. Based on the results, structural and non-structural measures are proposed to mitigate the impacts of flood events. © 2016, Geological Society of India.