RESIDENCE TIME OF BALIKPAPAN BAY

• Main Author: Tsabita, Tsamara
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/66308
• Institution: Institut Teknologi Bandung

Indonesia capital relocation issue to the Eastern Borneo region indirectly would increase the environmental degradation threats for Balikpapan Bay. One of physical parameters that possibly indicate the waterbody vulnerability against the environmental degradation is called residence time. Therefore, it is necessary to understand the residence time of Balikpapan Bay. This research has been done by simulating Delft3D-Flow 2-dimensional hydrodynamics model with particles tracking. Delft3D-Flow is a hydrodynamics modeling that apply Navier Stokes equation. Size of the model domain is 0,5°x 0,5° with 0,001° (±111,111 m) width grids. Models are simulated for 78 days with 300 seconds timesteps. Generating force of the hydrodynamics model is in the form of 8 tidal components and water discharge from 4 rivers. Four simulation scenarios that have been done, are scenario 1S and 1N with maximum discharge at spring tide and neap tide condition; scenario 2S and 2N with minimum discharge at spring tide neap tide condition. Model verification has been done by comparing model result data to observation data. Model verification results RMSE values of 0.11 m and 0.14 m; bias values of 0.001 m and 0.003 m; as well as coefficient correlation values of 0.99 and 0.98 for tidal elevation. Current velocity verification shows 8 out of 20 points have RMSE values that meet the criteria for good model results. The calculation result shows that the residence time of Balikpapan Bay varies according to four scenarios within the range of 13 – 20 days, the shortest residence time is from scenario 1S and the longest residence time is from scenario 2N. River discharge gives significant influence to residence time. Residence time difference between maximum and minimum river discharge of Balikpapan Bay is up to 4 days 11 hours 55 minutes, where the shorter residence time comes from maximum discharge condition. Although not as much as the river discharge, tidal current also significantly influences residence time. Residence time difference between spring and neap tide condition of Balikpapan Bay is up to 3 days 13 hours 38 minutes, where the shorter residence time comes from spring tide condition. Generally, the relative long residence time of Balikpapan Bay should be a concern for Balikpapan Bay environment manager.