Geomorphic assessment of longitudinal profile of the Kanchi river basin, India: Recognition of dynamic equilibrium condition

ABSTRACT The Kanchi, an eastward flowing river, traverses through the Ranchi plateau of the Proterozoic Chhotanagpur granite gneissic complex to meet its trunk stream, the Subarnarekha River. The present study analyzed longitudinal profiles and associated geomorphic indices of the Kanchi River and its tributaries to identify spatial variation in profile form and fluvial response to prevailing controls. This work was carried out using a digital dataset and maps, which were processed in a GIS environment to obtain longitudinal profiles, and different data required in best-fit modelling and geomorphic investigation of longitudinal profiles. The analyses indicate that the rivers are in dynamic equilibrium condition. Spatial distribution of geomorphic indices values reveals that longitudinal profile forms vary from one segment to another along river channels, and these irregularities in the form of prominent and minor knickpoints are highly concentrated in middle river basin areas. The absence of lithological variation and active tectonics, and close association of anomalously steep river segments with structural lineaments and landforms demonstrates structural control on river channel development. PCA denotes strong similarities between geomorphic indices. This understanding of longitudinal variation in river nature may help to formulate strategies for the sustainable development and management of river related resources.