Palaeo and present channel of Assi river, Uttar Pradesh, India

Abstract

The Assi river in Varanasi, Uttar Pradesh, India, is now a small, local, ephemeral floodplain tributary of River Ganga, with a length of about 8 km and catchment area of about 22 km2. It has also turned into a filthy drain. There are evidences in the form of palaeochannels, through patterns of water bodies and settlements along them, to suggest the origin of Assi river near Allahabad flowing through a distance of about 120 km up to Varanasi to meet the Ganga. There is also the possibility that Assi started as a takeoff from River Ganga and flowed as a Yazoo stream. Through on-screen digitization from high and medium-resolution remote sensing data-BHUVAN and Google Earth, CORONA aerial photographs, IRS P6 LISS-IV, Landsat 1, 3, 5, 7, 8-and a number of cross profiles from SRTM 30 m digital elevation model (DEM), palaeochannel of Assi has been delineated. Also, a 1 m DEM was generated for the present Assi catchment area from about 5000 DGPS points to present proof that the present Assi is a misfit in once a wider valley shaped by heavy discharge coming from a greater length of channel and a larger catchment area. © 2020, Indian Academy of Sciences.