Simulated response of seawater elevation and tidal dynamics in Jakarta Bay to coastal reclamation

The Jakarta Bay Reclamation (JBR) is a long-term protection project to prevent flooding in Jakarta. This study examines the effect of the JBR on water levels using the Regional Ocean Model (ROMS) to measure both the residual water levels (non-astronomic tide) and the total water levels generated by tides and Typhoons Hagibis and Mitag in November 2007. The results show that the tidal range in Jakarta Bay increased after the JBR, reaching 22.4% at Bekasi. The most significant amplitude change is S2 for the principal constituents and MK3 for shallow water constituents. The JBR does not change the direction of the propagation for S2 and MK3 in the Jakarta Bay, but it does change the phase lag. In addition, the JBR affects water elevations caused by tides and typhoons, with increased elevations between 2.69 and 11.53 cm. Although the aims of the land reclamation as a potential engineering solution are to provide for long-term protection against flooding from the sea, during the worst conditions (e.g., spring tides with perigee and remote forcing from typhoons), land reclamation will actually increase total water levels and amplitude of tidal constituents.