Wurjanto, A. and Mukhti, J.A., 2021. Hydraulic treatise of untreated water reservoir design of Indonesia's national capital integrated coastal development offshore dike. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 166–170. Coconut Creek (Florida), ISSN 0749-0208.
Coastal flooding and land subsidence are among the main issues for cities along the northern coast of Java Island. The Indonesian government planned to build integrated coastal protection along the northern coast. For the Capital City of Jakarta, the offshore dike will be complemented with a coastal reservoir to store freshwater for municipal uses. To overcome the occasional extreme weather, an untreated water reservoir (UWR) is required. This paper discussed the design of UWR pumping capacity and flood gate design of capital offshore dike through a hydrodynamic analysis with Delft3D. Flood hydrographs of extreme rainfall were created based on the data provided by the Ministry of National Planning. Bathymetry and tidal source were collected from GEBCO and NAOTide respectively. Hydrodynamic modeling was performed with variations on pump capacity and river input flows. The hydrodynamic model shows that the current UWR design can hold up to a 10-year flood without pumping. For more extreme floods, the UWR can also retain the water below the high water level with the help of pumps. The water elevation can be back to normal at -5.0 mLWS within a day of pumping with 1,600 m3/s.