River capacity prediction based on flood discharge probability scenario and sediment transport consideration: Study Case in Sayung River

Abstract

Pantura road at estuary of Sayung River is often flooded because it has a lower elevation than the river embankment. To avoid this, we must know the flood capacity of the river so that we can plan flood control and maintenance of river channels. Usually in flood prevention planning, it only design structure with unsteady flow model without sediment transport analysis. It is contrary with river nature because bed and river bank will easily erode, then transported as sediment and deposited in the lower reaches of the river. It makes river geometry will vary along with increasing of sedimentation. Therefore, capacity of the river will be analyzed with sediment transport using HEC-RAS 6.2 quasi unsteady flow model. Based on transport sediment simulation, sediment material deposition at Sayung River is 45,000 m3 every year. It makes river capacity decreased. Sayung River capacity is currently 242.15 m3/s, in 2023 is 200 m3/s, in 2024 is 185m3/s, in 2025 is 170 m3/s, year 2026 is 155 m3/s, in 2027 is 140m3/s, in 2028 is 120m3/s, in 2029 is 100m3/s, in 2030 is 77.5m3/s.