Analysis of water surface profile and flood discharge of Cijangkelok river

The downstream of Cisanggarung River Basin is often affected by floods with an increasing degree of intensity every year. For instance, the 2017 severe floods caused economic losses and fatalities, especially along the border of Cirebon and Brebes Regency. The flood was attributed to high rainfall intensity and the meeting point between Cisanggarung River and the Cijangkelok River. Therefore, a study on the flood in this area is highly vital to reduce the affected area in the future. This study aims to analyze the maximum flood discharge capacity in the Cijangkelok River and analyze cross-sectional river capacity using numerical model simulations. Based on the hydrological calculations and analysis, it is known that the planned flood discharge in the Cijangkelok River in the 5-year return period is 256,25 m3/s, the 10-year return period is 310,35 m3/s, the 25-year return period is 392,91 m3/s, and the 50-year return period is 465,93 m3/s. The analysis of the water surface profile of each flood discharge return period shows that overflow occurs in the cross-section 4090, 8254, 9166, 9753, and 11970. It is also revealed that the existing cross-section of the Cijangkelok River is unable to accommodate hydrological discharge. Field visit results show that the river has siltation or sedimentation, the river embankments are irregular, and land-use changes around the Cijangkelok River that affects the river.