STUDY HYDRODYNAMICS AND SEDIMENTATION ON PORT TANJUNG BALAI ASAHAN

• Main Author: FAJRIN WAHAB (NIM: 25015012), MUHAMMAD
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29196
• Institution: Institut Teknologi Bandung

<p align="justify">The Asahan River region consists of upstream and downstream ecosystems, the upstream region is Lake Toba Watershed and the downstream area consists of Asahan Watershed, Silau Watershed, Piasa Watershed, inflow from the catchment area of WS Asahan merges with inflow from Lake Toba coming out of S Asahan and together flow towards Tanjung Balai and empties into the Malacca Strait. So the supply of sediment from the river to the Tanjung Balai Port of the Asahan harbor is quite large. The results of field sampling stated that the sedimentary fraction on the river is silky sand. The influence of hydrodynamics on the Tanjung balai port is also a factor of sedimentation because it is adrift by the tidal currents of the Malacca Strait. Sedimentation in the port of Tanjung Balai Asahan has disrupted the shipping lane. Therefore, a further and in-depth study of the sedimentation is needed. To find out the hydrodynamics and sedimentation in the area concerned various methods can be used, one of which is using numerical modeling. Based on the results of the analysis obtained that the roughness value of manning used as calibration in the model shows the value of roughness gives the lowest error value after being verified by the current data from the field measurement. Results Measurements around the port have the lowest tide of -0.18 meters and the highest tide of 3.53 meters. The amount of current in the estuary is 0.02 - 0.5 m / sec, in the port bagan asahan is 0.1 - 0.75 m / sec, in the shipping channel the current ranges from 0.1-0.42 m / sec. At estuary locations, bagan asahan and shipping lines, the current that dominates is the tidal currents, while in the port of Tanjung Balai the dominating current is the current which is caused by the discharge from the upstream. <br /> <br /> <br /> The simulation results show the current velocity in the wet month is greater than the dry month, due to the larger discharge inflow. Likewise for sediment distribution, in wet months the concentration of sediment is greater than in dry months. The results of the sediment transport modeling indicate that sedimentation occurs in the area around the charred, river curves and the left and right of the river mouth asahan where in this area relatively low velocity which allows for sedimentation, erosion occurs in areas with a rather deep bathimetry which is the flow of water from upstream to estuary so that it has a relatively high current velocity resulting in erosion, the biggest erosion occurred in front of the harbor of bagan asahan. At Tanjung Balai harbor, sedimentation due to wet months is 0.75 m / year, while dry yield is 1.15 m / year. At the port bagan asahan erosion occurs, namely erosion due to wet months of -0.25 m / year, while due to dry months of -0.15 m / year. At the estuary, erosion occurs, namely erosion due to wet months of -0.18 m / year, while dry months result at -0.16 m / year. Sedimentation that occurs in Tanjung Balai Asahan port is greater when dry months are compared to wet months, this is because during dry months the flow velocity is smaller than the wet month so that deposition is more likely to occur. Likewise for erosion, erosion that occurs in the land chart and in the estuary is greater in the wet month because the current velocity is relatively larger this month. Assumptions for upstream handling reduced sediment supply by 34% and the effect of sediment zone embayment gave better results in solving sedimentation problems in the Tanjung Bene Port compared to dredging variations.<p align="justify">