THE BACKWARDS TRACKING OF DEBRIS PARTICLES USING THE EULER-LAGRANGE METHOD IN THE PELABUHAN RATU BAY

• Main Author: NURFADHIL BASUKI (NIM : 12913017), ILYAS
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/27988
• Institution: Institut Teknologi Bandung

<p align="justify">A common problem among coastal areas is the abundance of floating debris found in the waters of the ocean. As the second largest source of plastic debris in the world, Indonesia has its fair share of debris-related problems in various places. One such place that will be the focus of this study is Pelabuhan Ratu, located in the south-western part of Java Island. <br /> <br /> The purpose of this study is to determine the sources of marine debris found in the bay of Pelabuhan Ratu. To do this, a horizontal 2-dimensional hydrodynamic model is used to simulate ocean currents and tracki the individual pieces of marine debris backwards in respect to time using a Euler-Lagrange method, with each piece of debris treated as a single particle. The inputted data consists of bathymetry and debris positions, with the generating forces for the current being local wind speed and direction during the Western monsoon and the Eastern monsoon, and tidal elevation. <br /> <br /> The main result of the simulation is the tracking of the sources of each particle of marine debris. Results of the trajectory verification show a reasonable similarity between the results of backward particle tracking and forward particle tracking, with the majority of particles moving backwards coming close to the original positions used for forward tracking. Verifications also indicate a similarity between the trajectory distance of particles calculated in the program and the trajectory distance of particles calculated manually, as well as trajectory patterns that are in accordance with theoretical tidal currents. Elevation results from the simulation show similarites between its pattern and magnitude with that of the tidal predictions from the Geospatial Information Agency, though the phase is slightly different. The simulation reveals that tidal forces are the dominant forces and that wind currents also affect the length and direction of the particle trajectories. Backwards tracking in the Pelabuhan Ratu Bay results in very short particle trajectories caused by very small currents in the bay, indicating that marine debris in the bay originates from the coastal areas of the bay itself.<p align="justify">