The Ability of Red Mangrove, Gray Mangrove, and Mangrove Palm to Reduce Erosion Rate at The Northern Coast of Bengkalis Island Indonesia

Bengkalis Island has been experiencing a severe coastal erosion process, particularly on the northern coast. In 1955, the north shore of Bengkalis Island was protected by mangrove forest, which has a function as a natural barrier against coastal erosion. Currently, the condition of this area has been severely eroded due to the human activity of mangrove deforest. The coastal morphology of Bengkalis is a peatland and known as Bog Burst. Almost 70% erosion type that happens in Bengkalis Island are toppling failure and sliding failure, the effect of tidal wave oscillation promoted the formation and widening of tension cracks, parallel to the bank edge, the presence of tension cracks led to an unstable bank configuration, triggering mass failure, the tensile strength of the soil, so erosion occurs. Three types of mangroves that are often encountered in the northern coast of the Bengkalis island are namely red mangrove, grey mangrove and palm mangrove. This research aims to study the erosion process and the ability of all three types of mangroves in reducing the erosion rate at Bengkalis island from a numerical approach. Xbeach 1D model will be employed to simulate the wave attenuation in the mangrove tree and calculate the vegetation effect to reduce the erosion rate. The simulation results show that the mangrove palm, although only defined has 2 layers, namely the stem and canopy but overall have a better ability to reduce the erosion rate.