Suspended Sediment Distribution Corresponds to Erosion and Deposition Processes at Bengawan Solo River, Indonesia

摘要

Bengawan Solo River is one of the longest natural channels in Indonesia which functioned as irrigation, fresh water supply and flood control. This river covers up to 1.6x10~6 ha of area from the mountainous region in the Central of Java to the North Sea of Java with approximately 600 km of river reach length. Bengawan Solo River is an alluvial river indicated by Holocene formation along the river flow. Since alluvial soils were easy to transport, the river morphology changing becomes main problem. The river morphology changing causes local river channel alteration such as degradation, aggradation, river channel enlargement, and equilibrium of river profile. During this work, the suspended sediment concentration (SSC), flow discharge (Q) and flow velocity (u) were investigated as primary data through field work. The SSC provides the maximum and minimum value with 1496.868 mg/l and 294.308 mg/l respectively correspond to the climate succession in Bengawan Solo River basin area. The suspended sediment value shows the promising sediment equilibrium correlation with the river profile transformation tendency. Inequality between input and output sediment concentration in this study explains the mechanism of river channel alteration including deposition and erosion processes. Further, the correlation between flow regime which expressed by Reynold number (R_e) and SSC was presented to evaluate river channel changes.