by Pratama Rizqi Ariawan; (Thesis M.Sc Unesco-IHE, Delft, Netherland, 2016) supervised by Prof. Dr. Ir. Dano Roelvink, Prof. Dr. Ir. Robiyanto II. Susanto, M. Agr. Sc., and Dr. Ali Dastgheib.
Tanjung Carat, an area in Banyuasin estuary that is geographically strategic for port development in South Sumatra province, Indonesia. The area provides naturally deep draft, ease navigation, and a sheltered location from any incoming winds and waves. An old study about this area as an alternative solution for future port development has been proposed since 1975. Amongst those benefits, the estuary conditions are still gradually changing by active processes in morphological developments which are proven by several evidences obviously seen from satellite imagery as well as in situ measurements. Toward the lands, the estuary is a meeting pot for two river systems that are Banyuasin River and Lalan River. The interaction of suspended sediments carried by these rivers with tides which are dominated by diurnal tide has led to an expansion of an island inside the estuary for the period of 42 years.
Regarding a plan from the local government to develop a port in Tanjung Carat by implementing reclamation method, then this study will respond by conducting 2DH Depth-averaged model in Delft3D-FLOW for morphodynamics as well as hydrodynamics simulations for several pre-deflned layouts that are possible to build, among others rectangular layout, triangular with a sharped- edge layout, and triangular with a curved-edge layout. The 2DH model is considered to be suitable to be used in a well-mixed estuary as Banyuasz‘n Estuary.
Before conducting the simulation, setup was performed to schematize the models. During this step, bathymetry maps in 2012 obtained from Indonesian Navy combined with bathymetry data from Gebco were used as foundation of all simulations. Furthermore, one month calibration of tides were applied to represent real conditions of the estuary in terms of hydrodynamics. The calibrated model shows a good comparison with the observed tidal signals which were illustrated by non-significant deviation for both amplitudes and phases of each tidal constituents as well as a correlation of water level fluctuation in two different locations.
Meanwhile, morphodynamics simulations were carried out for 5 years. Morphological acceleration factor as well as morphological tides were implemented to accelerate and to reduce input for the model respectively. Bed Composition Generation was introduced to reproduce a stable condition of defined sediment fractions. Later, results of the model indicated that the trend of the erosion pattern tends to shift toward inland. In contrast, the sedimentation has no exact pattern but it will be more likely to be deposited toward the sea. The reason for this trend is due to current velocity generated during flood tide is higher than that of during ebb tide. By combining the morphological changes with three different layouts, the best fit layout will be proposed to be analyzed in hydrodynamics model after the construction.
The hydrodynamics modelling of the proposed layout aims to see any possible hydrodynamics changes due to the reclamation which may or may not cause a nuisance of flow pattern to a neighboring channel. Later in this study, it was found that the proposed layout will cause modest changes to the entire estuary both for morphodynamics as well as hydrodynamics.
Keywords: Tanjung Carat, Banyuasin Estuary, Delft3D-FLOW, 2DH Depth Averaged , Hydrodynamics, Morphodynamics