Waterfalls and rapids : what river knick points say about erosion of South Asian landscape

Continental great escarpments flank South India from the Sahyadri along the west coast to the broken Eastern Ghats of Tamil Nadu and Andhra Pradesh. These topographic walls are attacked by streams, and over geologic time they retreat back. Some retain their continuous form, like the Western Ghats south of Mumbai. Others, like the Eastern Ghats near the Cauvery River at Hogenakkal Falls, are cut by extensive gorges where drainage has been diverted from the upland to the lowland by river piracy. The over-steepened zones, or river knickpoints, migrate into the upland initiating a dramatic change of landscape. As the canyon passes upstream, the landscape goes from a rolling upland with thicker soils and low-relief stream courses to a rocky landscape of deep canyons and steep slopes. As the river basin approaches its new level of erosion, the landscape again returns to a low-relief form with erosional outliers such as the Yelagiri hills northwest of Pondicherry. The position and erosional nature of the knickpoints cutting the Eastern Ghats escarpment are being studied using remotely sensed topographic and satellite data, as well as field sampling and analysis of soil and rocks for erosion rate along the knickpoint.

Speaker

Dr. David Harbour, Washington & Lee University, USA

Organisers

Laboratory of Geomatics & Applied Informatics
French Institute of Pondicherry

Venue

Jawaharlal Nehru Conference Hall
French Institute of Pondicherry
11, Saint Louis Street Pondicherry - 605 001