Assessment of sediment movement pattern along nearshore coastal water of Cox's Bazar

Abstract

Cox‟s Bazar is the most important Coastal district of Bangladesh. Coastal resources provide here the opportunities to use the coast in different ways within the hazard-prone environment. The shape and orientation of the coastal landforms near Cox‟s Bazar is primarily based on sediment transport. Mathematical model can be used successfully to forecast this sediment movement pattern in nearshore coastal water of Cox‟s Bazar. Validity of forecast in sediment transport depends on both mathematical modeling technique and boundary conditions. In this research a numerical two dimensional hydrodynamic Depth Integrated Velocity and Solute Transport Model (DIVAST) has been set up at nearshore coastal water of Cox‟s Bazar to assess the sediment movement pattern. An observation was made on the condition of suspended sediment and bed load along the study area by changing wave angle for 2 cases, one is for the boundary condition generated within the study area (case 1) and another is for the boundary condition generated outside of the study area from deep sea (case 2). The model output for both suspended and bed load is representing here one by one plotting them in surfer software to visualize and assess the sediment movement pattern in nearshore coastal water of Cox‟s bazar covering three very important beach of Bangladesh, kolaboti beach, Laboni beach and Inanibeach and the adjacent area of Moheshkhali channel. At first, the model was run for the wave angle 230o. Gradually it was changed for every 10o and the model output is presented here up to wave angle 290o. Some selected model output for wave height and radiation stress is also presented in this thesis paper. The wave angle 230o for case 1 and 240o for case 2 were found most critical because of a considerable amount of suspended and bed load movements occur with these wave angles. The amount of sediment concentration has found to be negligible for incoming wave angle of 260o, 270o and 280o. After 290o the suspended sediment movement and after 270o the bed load movement was found insignificant. The sediment concentration is higher along the shore line than the other point of the study area.