Sedimentary structures and facies analysis of the Ghaghara River, Ayodhya, Uttar Pradesh, India: A Case Study

The Ghaghara River originates from the Mapchachango glacier near Mansarovar lake and spreads over many parts of India and Nepal. It is the left bank and largest tributary of the Ganga River by volume. It confluences with the Ganga River at Doriganj near Chhapra town in Bihar. Extensive studies have been carried out on flooding and lateral erosion, but no attention has been paid to sedimentary structures and facies along the Ghaghara River. The present study is focused on the facies analysis and sedimentary structures, which are exposed on a 196 cm high cliff section (Upland terrace surface T2), along the Ghaghara River, Ayodhya Ghat, Uttar Pradesh. The facies are the paleosol unit (Facies I), silty unit (Facies II), and sandy unit (Facies III), which show high energy conditions and a high degree of transport rate while the mud unit (Facies IV), show low energy conditions and low degree of transport rate. The sedimentary structures have been identified such as the massive bedding in silty unit, planar cross-bedding and trough cross-bedding in sandy unit, and parallel laminations in mud unit at different depths of litholog. It also indicates that fluvial hazards occur during low-discharge periods due to sandy, silty, and muddy facies in the river valley deposits, which contribute to increased lateral erosion in the low discharge period and flooding occurs during the high-discharge periods.