Hydrodynamics Modeling of Giant Seawall in Semarang Bay

Abstract Semarang bay was located in the Central Java Province has problems of land subsidence, inundation, limited land and shortages of fresh water. One of the efforts to solve the problems is by buildinga giant seawall in Semarang bay. BPPT, according to its function and task has a concept of the giant seawall (GSW BPPT concept). The aim of the study is to simulate the hydrodynamics, i.e. surface elevation and sea current components, of the existing condition as well as the GSW BPPT concept. Modeling was carried out using the software package MIKE21 HD FM module, developed by DHI Water and Environment, Denmark. The GSW BPPT concept conFigures 3 lakes with the stored water coming from the existing river flows. The model shows that the GSW BPPT concept changes the hydrodynamic patterns in the area within 5 km from the structure, and may increase the discharge of fresh water by 140 m 3 /sec in western lake, 57 m 3 /sec in central lake and 46 m 3 /sec in eastern lake.