Present geomorphic categorization of alluvial channel reaches using channel dimensions and geomatics in the damodar river of West Bengal, India

Abstract

Quaternary to Recent floodplains and the channel bed of the Damodar River (West Bengal, India) are gradually formed by a complex interaction of fluvial processes and anthropogenic processes but their character and evolution are essentially the product of stream power, channel dimensions, and sediment character. The relation between a stream’s ability to entrain and transport sediment and the erosional resistance of floodplain alluvium (that forms the channel boundary of the Damodar River) provides a basis of genetic classification of alluvial reaches and floodplains. The alluvial segment of the Damodar River, in between Rhondia (23°22′08′′N, 87°28′25′′E) and Paikpara (23°00′58′′N, 87°57′41′′E), was selected as the study area to identify its special hydrogeomorphic individuality and multidimensionality. The pattern and configuration of the fluvial landscape of the Damodar was recognized using ASTER DEM, GIS analytical tools, channel dimensions, and multivariate statistics, treating each segment of channel and cross-sectional profile as a unit of geomorphic study. The analysis showed that the Damodar River (Rhondia to Barddhaman) was regarded as a bed-load channel with a medium-energy noncohesive floodplain upstream of the study area, and the downstream stretch (Basrsul to Paikpara) was identified as a mix-load channel with a low-energy cohesive floodplain. Multivariate statistical analysis categorized the study unit of the Damodar River into two parts: the upstream section of the river tended to braiding and lateral expansion, and the downstream section of the river tended to meandering and lateral confinement.