Since 2014 sedimentation at the estuary of Jelitik river, Sungailiat, Bangka has continued to increase. At this estuary, the ship traffic is very busy and there is National Fisheries Port Sungailiat. When the tide is low, the river mouth closes thus disrupting ship traffic. The Bangka Belitung Provincial Government is currently planning to build a sediment control infrastructure to reduce the sedimentation rate. To plan and determine the effectiveness of the jetties requires knowledge of sedimentation patterns around Jelitik estuary. Therefore this study was conducted to determine the pattern of sedimentation (distribution and rate) at the existing and ultimate conditions. The methods are field survey, analysis of field data, and computational modeling of sediment transport. Modeling of sediment transport was done using the Sand Transport Module of MIKE 21. Two scenarios were simulated for the existing and ultimate conditions. Based on this modeling, the sedimentation rate at Jelitik estuary is found uneven. In the existing condition, a large rate of sedimentation occurs on the southern side of the Jelitik River estuary, which reaches a maximum value of 2.75 m/year, with an average of 4.44 cm/year. Whereas in the ultimate condition, the sedimentation rate decreases to 0.0377 m/year.

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Research on wave forces attacking a vertical structure has been conducted worldwide. Morison’s equation commonly used to describe the phenomenon of the action for offshore structures, while for nearshore structures Goda’s equation is more reliable. Wave impact on vertical breakwaters is dangerous for vertical structures, both for walls and columns. Wave pressure distinguished for wave crest and wave trough, assumed to be distributed as a trapezoidal shape like along the vertical wall. The wave force consists of wave pressure on the front of the vertical wall and buoyancy, and uplift pressure in the vertical direction. In this research, a 2-dimensional physical modelling is carried out to observe the response of a vertical structure due to a wave action. Wave forces are measured using a flexi force sensor for both horizontal and vertical forces. Time series of incident wave and waveforces acting on the structure are recorded simultaneously and it clearly depicts the relation between them. The wave forces at the structure are linear to the height of the action waves. Periodical wave action results in the pushing forces at the structure to be higher than the pulling forces, as extra drift forces appear due to the shallow water wave condition.

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Understanding of transport processes of discharged sediment through the river in coastal area is crucial for prediction of coastal bathymetry evolution. In case that fine sediment is dominant in sedimentary system, the transport process becomes complicate with the formation of fluid mud, which may be an important role on the transport and distribution of muddy sediment. The aim of this study is to elucidate the fine sediment dynamics, which may have a key role on the deformation of the deltaic topography around the estuary, in a tropical climate environment where experiences apparent seasonal variation of river discharge due to the wet and dry weather condition.