Evaluation of the depositional environments and the spatial variations of grain size characteristics of Ramganga River sediments, India

There has been an increased interest in erosion processes and the transportation of materials by rivers due to their importance in land utilization and environmental considerations.Evaluating sediment yield and grain size is essential for examining sediment erosion rates, designing reservoirs and dams, predicting the effects of anthropogenic activities and climate change on river systems, and understanding the occurrence of heavy and trace metal contaminants and micropollutants.In this study, twenty-seven samples of bed sediments were obtained from the main channel of the Ramganga River and its tributaries.The sediments were further filtered via a series of stacked sieves with different mesh sizes along with a receiving pan.Each particle size fraction in every sieve, including the pan, was collected, weighed, and noted to identify the hydrodynamic conditions and depositional environments using bivariate plots, linear discriminant function (LDF), and a Passega diagram.The results indicate that the studied sediments exhibit unimodality, with only two bimodal samples in the midstream region.Folk's classification system categorizes the samples into four distinct classes: coarse sand, medium sand, fine sand, and very fine sand, with proportions of 4 %, 33 %, 52 %, and 11 %, respectively.The findings indicate that the upstream samples exhibit the coarsest particle size, are poorly sorted, and are transported through rolling mechanisms.The midstream and downstream samples are finer in size, well sorted, and carried by higher levels of suspension.