Morphometric analysis of Nandakini River Basin, Garhwal Himalaya, Uttarakhand using geospatial technology

Abstract

Basin morphometry is a crucial method of analysis to understand the geology, lithological structure,
inltration rate of rainwater, runoff, eroded load carrying capacity and ooding potential of a drainage
basin. The quantitative techniques applied for linear, areal and relief aspects of the drainage basin
elucidate the rate of erosion, the intensity of denudation and subsequently the potential of the Nandakini
river basin to ooding. The morphometric analysis of the Nandakini river basin in the Garwhal Himalayan
region of Uttarakhand reveals that the Rf value of the Nandakini river basin is 0.28, indicating an
elongated basin shape leading to quick ooding and poor draining out of oodwaters. Similarly, an
elevation difference between the highest and lowest elevation is 5380 which metres aids quick runoff and
deposition of eroded debris in the drainage channels, another cause of channel overow. The Rh value is
high (0.12), indicating a high channel gradient with intense erosional processes operating due to steep
gradient and this has a considerable impact on the rate of erosive geomorphic processes operating. The
higher elevation on the Eastern part of the basin due to the Vaikrita Thrust, the Munsiyari Thrust (ie. the
southern tilting Main Central Thrust) and the Baijnath Klippe has resulted in metamorphism in Miocene
and Pliocene explaining the low rate of inltration and rapid runoff.