Numerical modelling of a tidal lagoon along the North Wales coast

This study examines far- and near-field impacts of a coastally attached tidal lagoon proposed along the North Wales coast. A two-dimensional numerical model, based on an unstructured triangular mesh, has been refined to simulate the hydrodynamic processes, initially without and subsequently in the presence of a tidal lagoon. The model adopts a TVD finite volume method to solve the 2D shallow water equations based on a second-order accurate spatial and temporal numerical scheme. Results indicate a good performance in reproducing the established conditions encountered in the region through comparisons against available data. The operation of the tidal lagoon has a considerable effect on the flow structure near the region, by inducing high velocity accelerations near the sluices and turbines of the impoundment, depending on the stage of the tidal cycle. Considering an ebb-only generation, it is highlighted that such tidal lagoons can additionally mitigate the risk of coastal flooding by substantially reducing the maximum water levels on the upstream side of the structure.