Seasonal variations in sediment characteristics at the estuary of Bengawan Solo river: A study of river branching and flow velocity influences

This research investigates the dynamic of sediment deposition in estuaries, focusing on the role of river branching and flow velocity, aspects that have not been comprehensively studied before. The study assesses the variation in sediment deposition characteristics before and after a river branch over a year. Monthly bed sediment samples were taken for a period of one year, which included both the monsoon and dry season and were tested using sieve analysis for sediment classification. Flow velocity, previously modelled using HEC-RAS, was considered when evaluating sediment deposition patterns. Preliminary findings reveal a marked seasonal variation in sediment characteristics. During the monsoon season, sediments upstream of the river branch predominantly comprised medium-to fine-grained material. Conversely, downstream of the river branch, a similar sediment texture was observed primarily during the dry season. It is concluded that while the river branch plays a substantial role in dictating sediment deposition characteristics, the impact of flow velocity must also be acknowledged. This research, therefore, adds a new dimension to the understanding of sediment deposition patterns and characteristics in estuaries, particularly the interactive influence of seasonal variations, river branching and flow velocity. This can have important implications for estuarine ecosystem management and sediment-related hazard prediction.