HYDRODINAMIC MODELLING OF CIPUNEGARA COASTAL RESERVOIR WITH DELFT3D

• Main Author: Ulumit Tias, Devi
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/71137
• Institution: Institut Teknologi Bandung

Infrastructure development on the coast of Java Island, especially in the Cipunegara estuary, is happening quite rapidly, especially with the construction of the Patimban Port which is projected to support economic development in the Cirebon-Subang-Majalengka Region (Rebana Area). This will lead to potential problems, including land subsidence and a shortage of clean water sources. To the west of the Patimban Port construction site is the Cipunegara estuary, a medium-sized river which may be suitable as a source of fresh water for the Patimban Port area. The Cipunegara Beach Reservoir is expected to be able to accommodate fresh water from the river and can provide a solution to the problem of raw water needs. However, the location of the Cipunegara Coastal Reservoir which is at the mouth of a river raises concerns that fresh water will mix with sea water. Therefore it is necessary to study the modeling of the physical aspects of the sea to determine the extent of the influence of sea water on the land which will then determine the operational pattern of coastal reservoirs. Delft3D-Flow modeling is carried out by entering the main inputs in the form of tidal elevation and discharge of the Cipunegara river. The discharge used varies according to the modeling scenario, ranging from constant discharge, dry season discharge, and rainy season discharge. In the initial simulation, the Cipunegara river channel was maintained as natural conditions, but because primary bathymetry data was not owned, the river bathymetry was modified to a depth of -4 m LLWL at the estuary and getting higher upstream. In the next simulation, the addition of a rubber weir structure was carried out as an infrastructure for flood control and prevention of seawater intrusion. From the initial simulation results, namely without any intervention in the Cipunegara river channel, it is known that during the rainy season the position of the coastal reservoir inlet is not affected by tides because sea water only enters as far as 3 km upstream. Filling of coastal reservoir water (sluice opening operation) is recommended to be carried out in this condition. In the dry season, the position of the entrance to the coastal reservoir is affected by tides because sea water enters up to 21 km upstream. It is recommended that the coastal reservoir sluice be closed to prevent seawater intrusion into the coastal reservoir. However, the above operating pattern does not allow the Cipunegara coastal reservoir to act as an optimal raw water provider for the Rebana Area because it can only take water in certain seasons. With the addition of a rubber weir infrastructure in the Cipunegara river channel, the modeling results show that the rubber weir effectively separates seawater from fresh water, so that the entrance to the Cipunegara coastal reservoir can be opened at any time regardless of the season. then the raw water needs of the Rebana Area can be fulfilled.