Physical Control on Marine Debris Spreading around Muara Gembong, Jakarta Bay

The Citarum River flows through different characteristic of terrestrials with 297 km length and become one of the largest rivers in West Java. It potentially transfers debris from land into the sea. This research aimed to define the Marine Debris (MD) trajectories based on seasonal monsoon. The method used was numerical analysis combined with artificial debris pathways. The simulation controlled by ocean currents, tide, wind pattern, and bathymetry conditions. The MD observations were conducted in four mouth of estuaries across the Muara Gembong areas. These simulations with specific time during two main monsoons (the northwest and southeast Monsoon) period. The results showed that the debris trajectory patterns vary in the two monsoons. The macro debris trajectory showed the waste patterns similar to oceanographic condition, especially the ocean currents pattern. The trajectories of waste from two estuaries flow towards the south and southwest follow the coastal contours. Specifically, in Northwest Monsoon, MD spread to the south and was stranded in the surrounding coast areas. In Southeast Monsoon, MD was forced to the central of Jakarta bay and surrounding islands in the western and southern side of the estuaries. Compared to the Bendera estuary, the MD that comes from Jaya estuary affects the surrounding areas, including in the northern side and southern side.