Tectonic effects on the longitudinal profiles of the Chaliyar River and its tributaries, southwest India

Abstract Chaliyar River, a west-flowing river, originates at about 2300 m elevation in the Western Ghat hill ranges in the southern part of India. We have studied geomorphic aspects of this river by examining longitudinal profiles and drainage pattern in order to understand the rock uplift and river incision. Chaliyar River and its tributaries display uneven longitudinal profiles with numerous knickpoints along the profiles. River concavity and river morphology were analysed to better understand the influence of tectonics and rock uplift on the fluvial and topographic system in the Chaliyar River basin. Wide variability in the concavity index of the tributaries of the Chaliyar River reflects the role of tectonism in carving the present river profiles. Steepness and concavity indices computed for the longitudinal profiles suggest that the rate of uplift is exceeding the rate of incision and are independent of lithology. River incision is not uniform in the Chaliyar River. The streams become graded (absence of knickpoints) towards the river mouth, suggesting that the uplift and incision are in equilibrium.