Analysis of Komolino-Lino River Flow Using HEC-RAS 6.4.1

Sedimentation in the Komolino-Lino River channel with a watershed area of 36.90 km2 has reduced the river's capacity. This causes flooding that inundates plantations, irrigated rice fields, residential areas, and social facilities. This study analyzes the river's capacity to pass the design flood discharge and its handling solutions. The research stages include primary and secondary data collection and hydrological and hydraulic data analysis. Primary data in the form of situation measurements, lengthwise and across the river. Secondary data in the form of rainfall data and Komolino-Lino watershed maps. Rainfall data used Hek-Bunta Station with observations for the last 10 years (2014-2023). Design rainfall is calculated using the Log Pearson III Method according to the appropriate statistical parameters. Design flood discharge is computed using the Haspers, Weduwen, HSS Nakayasu, and HSS Snyder Methods. River hydraulic analysis uses the HEC-RAS 6.4.1 program. The selection of discharge and method used depends on the results of the initial HEC-RAS run on existing conditions and the appropriateness of the planned dam. From these results, the design flood discharge Q25 = 150.777 m3/sec was selected using the Snyder HSS Method. From the simulation results of existing conditions, the Komolino Lino River is unable to accommodate flood discharge at a 5-year return period, even in some river sections there is an overflow at an annual discharge (1.01). Therefore, river normalization and river embankments were carried out with an average height of 1.0 m