Sediment Characterization of the Gorai River in the Pre-monsoon and Post-monsoon Period: Effects of Decreased Ganges Flow in Bangladesh

Abstract

The present experiment was carried out to investigate the grain size distribution and ionic composition of Gorai riverbed sediments. The majority of the particle size distribution of the Gorai riverbed sediments fell between 101 and 250 µm (0.1-0.25 mm). The light fraction constitutes up 80–85% of the Gorai riverbed's sediment. The post-monsoon season has a higher concentration of cations in the sediments than the pre-monsoon season. In all sampling seasons and at all sampling stations, the sulphate (SO42-) level was much greater than the phosphate (PO42-) content. Nonetheless, the post-monsoon season has a lower PO42- content than the pre-monsoon season in the majority of the locations. An abundance of minerals, including PO42- and the release of PO42- from agricultural land and urban areas following the monsoon season in the catchment region might lead to high levels of PO42-. The reduced Ganges flow most likely alters the concentration and composition of various chemical components, negatively affecting the environment. According to the study, the Gorai River system has silt pollution as a result of the ' decreased flow of the Ganges. These changes may further harm groundwater resources in the region under study. Sedimentation impacts fish and aquatic living organism habitats, modifies stream flow, diminishes irrigation water consumption, and presents challenges for recreational and navigational activities.