ANALISIS MITIGASI KEJADIAN BANJIR SUNGAI WATUDAKON DI KABUPATEN JOMBANG DAN KABUPATEN MOJOKERTO

Abstract

Watudakon River is one of the rivers in East Java that flows through Jombang Regency, Mojokerto Regency, and Mojokerto City. One of the water structures in the Watudakon River system is the Watudakon Siphon which functions to channel water to the Mas River via the Brantas River. Floods occur frequently in the Watudakon River area due to deposition along the river body, as well as disturbances in the form of rubbish and sediment in the flow of the river body towards the siphon so that the channel capacity is increasingly reduced. Therefore, based on the 2019 planning, a trash rack was built at the Watudakon Siphon inlet. This study was carried out to analyze and provide an overview of the disentangling changes in the Watudakon River bed profile, both the design conditions based on the 2019 Plan and the conditions of alternative flood control designs. The methodology used in this study is hydrological analysis using HSS ITB-I, as well as hydraulic analysis of floods and sedimentation using the HEC-RAS 6.2 program. Based on the analysis results, several flood control design scenarios were modeled, one of which was the normalization and retention pond construction scenario with an open channel outlet system. Under these conditions, mitigation measures for river water blockages can reduce the water level by 1.1 meters in downstream areas.