Inhibition of Ekortikus Island Expansion in Banyuasin Estuary, South Sumatra Modelling by Using Finite Volume Method with Unstructured Mesh

Ekortikus Island was formed through continuous sedimentation in Banyuasin Estuary (BAE) in Banyuasin District, South Sumatra. Based on satellite data, Ekortikus Islands area is expanding dramatically, 22 times greater in 21-year period. This expansion narrowed the estuary and disturbing estuary function, especially related to water run off from water cathment area. Ekortikus expansion was caused by high sedimentation and flow distribution mode which were formed by the fusion of two river flows assembled in the estuary, confounded by tidal flow dynamic with amplitude of 0.6 – 3.9 m. An experiment was conducted to simulate development of Ekortikus Island with or without placement of a potential barrier. The simulation used Finite Volume Method (FVM) with triangle unstructured mesh. Simulation with normal conditions or without treatment, in which the flow is Banyuasin greater than the flow Lalan turn out Ekortikus island increases toward the Southwest and due to tidal flow, Ekortikus Island increases towards the Northwest. Simulation could also manipulate the future form of the Island when a potential barrier was placed to direct flows of both rivers. Treatment simulation, by changing the flow Banyuasin becoming greater than Lalan flow, altered the location of the deposition of sediment to another place and Ekortikus Island area expansion was reduced.