Hydro-morphodynamic modelling of mangroves imposed by tidal waves using finite element discontinuous Galerkin method

Modelling the hydro-morphodynamics of mangrove environments is key for implementing successful protection and restoration projects in a climatically vulnerable region. Nevertheless, simulating such dynamics is faced with computational and time complexities, given the nonlinear and complex nature of the problem, which could become a bottleneck for large-scale applications. This study investigates the effect of mangrove environments on the hydro-morphodynamics of its region. A depth-averaged model was built using a novel finite element model for simulating coastal models, within Thetis. The Sundarbans, the largest mangrove forest in the world located between India and Bangladesh, is taken as a case study. The Sundarbans is regularly subjected to tropical cyclones, the impacts of which endanger the lives of the region’s four million people. This is a first-time application of a coupled hydro-morphodyamic model using discontinuous Galerkin finite element discretisation for modelling mangrove environments in a real-world application. A wetting drying scheme was implemented in the models in order to avoid numerical instabilities. The effect of mangrove environments is demonstrated ,by imposing a periodic tidal boundary, conditions using TPXO tidal solver, using experiments with and without mangroves. The model is validated against the results of another study on the same region and tidal gauge data. Mangrove environments are able to decrease water elevations and velocities by more than 97%, and prevent almost any sediment erosion when compared with the experiment with no mangroves.