Rajiv Sinha
IIT, Kanpur
Rajiv Sinha is a Professor of Earth Sciences at IIT Kanpur. He holds a PhD in sedimentology from the University of Cambridge (1992) and has worked on various aspects of river science during his career. Apart from his early work on proposing a new source area classification of Gangetic river systems, one of his most significant contributions has been characterising geomorphic diversity and landscape evolution across the Gangetic plains as a function of the balance between stream power and sediment flux. His recent research on paleochannels in northwest India has suggested that no large river was contemporaneous with the Harappan civilisation in this region. He has published over 200 papers with over 9000 citations (h-index 57). He is a recipient of the Alexander von Humboldt Fellowship (2000), National Mineral Award (2002), and S S Merh Award (2006). He is an elected Fellow of the Indian Academy of Sciences (2021) and the National Academy of Sciences (India).
Session 2C - Lectures by Fellows and Associates
Somdatta Sinha, IISER, Mohali
Riverscape dynamics in the northwestern Himalaya and its non-contemporaneity to the Harappan civilization
A large perennial river system (Ghaggar-Hakra), comprising paleo-Sutlej and paleo-Yamuna Rivers, has been argued to have sustained the Bronze Age Harappan urban settlements (-4.6-3.9 thousand years before present, ka) in the northwestem Indian plains. Based on comprehensive chronostratigraphic, sedimentological and sediment provenance data, our work has shown that the palaeo-Sutlej was already defunct in this region by - 8 ka. The Harappan urban settlements thus developed along an abandoned river valley rather than an active Himalayan River. Further, the paleo-Yamuna also acted as an important feeder to the Ghaggar-Hakra system, which impacted the local hydrological conditions, although its role in the growth and eventual demise of the Harappan settlements has been debated. Our new data on high-resolution chrono-stratigraphy from six sediment cores (-50 m deep) across the palaeochannels of the Yamuna document multistoried sand bodies deposited by a mobile channel belt in a large fluvial fan system. Based on extensive luminescence dating, we infer a major drainage reorganization of the palaeo-Yamuna River at -18 ka, at least 10 ka before the westward switch of the paleo-Sutlej River. This means that the Ghaggar-Hakra system was already flowing with a much-reduced discharge during the Early Holocene and was completely defunct by-8ka, much before the decline of the Harappan Civilization started.