Morphology Changes Affected by Sediment Concentration and River Flow in Meandering Channels of the Bengawan Solo River

Abstract

Increases in critical land in the Bengawan Solo River Basin contribute to floods and severe damage to infrastructures along the river channel. Additionally, the occurrence of excessive erosion is a source of sediment materials, especially at meandering sections. Riverbank erosion destabilises dykes and sediment deposition decrease capacity, thereby resulting in floods (especially during rainy seasons). Although both phenomena can be evaluated by observing flow velocity and sediment concentration, there is a paucity of field investigations on parameters that affect erosion under dry and rainy seasons. This study investigates the aforementioned parameters and contrasts circumstances during dry and rainy seasons by presenting relevant information on sediment quantity and flow velocity. The results indicate that sediment concentration at the outer banks of the flow path significantly exceeds that at the inner banks, thereby indicating significant occurrence of erosion. Further examination of riverbed material suggests that the interaction between sediment concentration and flow velocity, especially in meandering segments, can provide an estimate of the erosion rate and the change in the morphology of the alluvial river. Sediment concentration is correlated with seasonal conditions such that sediment concentration during the rainy season is approximately five times that in the dry season. This clarifies that more significant river morphology changes occur during peak seasons. Further, the results of the study can be used in river dynamic process prediction, especially in alluvial streams or in soft soil with properties similar to that of alluvial streams.