Late Quaternary Geomorphic Evolution of the Coastal Zone of Kachchh, Western India

Abstract

The present study attempts to delineate the late Quaternary morphotectonic evolution of the coastal zone of Kachchh on the basis of detailed field mapping of the various coastal and fluvial landforms and lithostratigraphic studies of the associated sediments. The entire coastline has been divided into five morphologically distinct segments from west to east—Narayan Sarovar–Jakhau, Jakhau–Khuada, Khuada–Bhada, Bhada–Mundra, and Mundra–Surajbari segments. Major geomorphic features of interest are the variable width of the intertidal zone; development of beaches, bars, and spits; width of active and stabilised coastal dunes; raised mudflats; raised beaches; uplifted estuarine tidal terraces; and the development of a coastal alluvial plain in the Jakhau–Khuada and Bhada–Mundra segments. The coastal alluvial plain was formed by deposition of fluvial sediments over the peneplained Tertiary rocks during upper late Pleistocene in two separate tectonically created basins. Deeply incised fluvial valleys were formed in response to tectonic uplift of the coast due to movements along E-W trending faults further north during the early Holocene. The sea level was higher than present during 6–2 ka, which led to the deposition of coastal sediments, fluvial terraces along incised fluvial valleys, and formation of a cliffy coast in the Narayan–Sarovar–Jakhau segment. Emergent coastal features consisting of raised beaches, raised mudflats, abandoned coastal cliffs, uplifted estuarine tidal to fluvial terraces, and stabilised coastal dunes developed because of uplift during the last 2 ka. The various morphotectonic divisions of the coast are attributed to the role played by the inherent structural fabric, the subsurface Median high, and general uplift of the coast due to tectonic activity along the E-W trending faults to the north of the study area during the early Holocene and the last 2 ka.