EARTH SURFACE PROCESSES AND LANDFORMS, VOL. 20,407-421 (1995) zyxw CHANNEL FORM AND PROCESSES OF THE FLOOD-DOMINATED NARMADA RIVER, INDIA S. N. RAJAGURU zyxwvut Department zyxwvuts of Archaeology, Deccan College, Pune 41 1006, India AVIJIT GUPTA Department of Geography, National University of Singapore, Singapore 0511 V. S. KALE Department of Geography, University of Poona, Pune 41 1007, India SHEILA MISHRA AND R. K. GANJOO Department of Archaeology, Deccan College, Pune 411006, Indir L. L. ELY, YAHOUDA ENZEL AND V. R. BAKER Department of Geosciences, University of Arizona, Tucson, zyxwvu A2 85721, U.S.A. Received 13 April 1993 Revised 13 June 1994 ABSTRACT The 1300 km long Narmada River flows along a structural lineament, alternating between constricting rocky gorges and rapids, and meandering wide alluvial reaches. Channel forms and processes were studied in a 120 km long section of an alluvial reach. Channel size, shape and bedforms in the Narmada River are related to very large floods which have occurred three times in this century. During such floods the entire 400 m wide channel is utilized and 10- 15 m high cliffs on both sides operate as riverbanks. Normally, even the high flows of the south-westem monsoon are insufficient to fill the whole channel, and hence their effects are limited to building of discontinuous floodplains between the cliffs and modifying bedforms and bars. A channel-in-channel topography is thus created. The very large floods are also responsible for erosion of the rocky stretches and building of point bars. The river meanders, but its movement is restricted because of (1) rocky gorges and scablands operating as anchor points at intervals, and (2) the presence of high alluvial cliffs which are topped on extremely rare occasions. In spite of being located in a tectonically active zone in a monsoon setting, it is the exceptional high-magnitude floods at irregular intervals which control the form and behaviour of the Narmada River. KEY zyxwvutsrqponm WORDS flood geomorphology; seasonal regime; shear stress; point bar INTRODUCTION The 1300 km long Narmada is a fascinating river. It passes repeatedly through constricted rocky gorges and rapids to expand into meandering alluvial reaches. Pleistocene fossils and human artifacts have been found for over 150 years in its sediments, and recently the Narmada has been the subject of controversy concerning the planned series of dams and reservoirs along its course. zyxwv A considerable volume of literature has grown on the geology, hydrology and archaeology of the basin, but very little organized information exists regarding the geomorphology of this tropical monsoon river. A primarily morphological study of the lower Narmada flowing through an alluvial plain has been published (Bedi and Vaidyanadhan, 1982), but the present paper is probably the first detailed account of a reach of the Narmada and its processes. This paper describes valley geology, the alluvial stratigraphy, the channel forms and the operating CCC 0197-9337/95/050407-15 zyxwvutsr 0 1995 by John Wiley zyxwvutsrqp & Sons, Ltd.