Application of the HEC-RAS Program in the Simulation of the Streamflow Hydrograph for Air Lakitan Watershed

Floods are an issue that results in losses, and thus attempts to solve the problem of flooding are attempts to minimize losses. To mitigate the losses incurred as much as possible, there are several approaches to deal with the loss through incident management and its impacts. The objective of this study is to investigate the variations in water level within Air Lakitan Watershed to monitor the fluctuations of water level for preventing flooding issues in the future. This research was carried out by analyzing the hydrodynamics of flow in irrigation canals in Irrigation Area II with an area of 928 hectares using the HEC-RAS program with rainfall data and flow hydraulics data. The study was carried out in Air Lakitan Watershed in Sumber Harta District, Musi Rawas Regency, Sumatra, Indonesia. Each portion of the studied irrigation canal’s water level and velocity, as measured by a current meter, are shown on graphs, as are the study’s overall conclusions for each observation station along the channel. Simulated data was acquired using a river crossing that is not filled and a discharge of 0.024 m3/s. From this research, it can be concluded that the Log-Pearson Type III distribution is the frequency distribution that matches the hydrological analysis in the research area. This method can be applied in analyses of river levels in other areas with heavy rainfall. Therefore, the water level upstream and downstream is the same at 0.41 m with a discharge of 1 m3/s; the river cross-section downstream with an existing discharge of 0.024 m3/s produces water height as high as 0.08 m and with a flow rate of 0.783 m/s, the water level at the downstream cross-section is filled up to 0.75 m high, and the water level downstream of the irrigation channel is up to 0.40 m.