09. Recovering mangroves with wooden fence along Mekong deltaic coast: physical mechanism and SWASH model

Abstract

The Mekong deltaic coast has been suffering from erosion that negatively affects the mangrove forest for the past decades, especially in the era of sea-level rise and climate change. Building alongside traditional coastal structures, porous structures, i.e., wooden fences, become sufficient support for restoration mangroves that are already squeezed significantly. This study presents the flow and wave reduction mechanism due to the wooden fence and validation for wave-fence interaction in the SWASH model. The application of the Darcy-Forchheimer experiment delivers a proper drag coefficient that is dependent on the Reynolds number. This coefficient has high values at the laminar flow condition, Re < 400, and becomes stable as 3.8 at the high turbulence, Re > 800. The relationship between the drag coefficient and Re has finally been found, which is the base for the SWASH model's validation of wave-fence interactions. With the data from the physical model, this model shows high confidence during the comparison. The results show low errors for incoming and transmission wave heights as 3.2 % and 4.6 %, respectively.