The main objective of this proposal is to develop a mathematical model to simulate the sediment transport and coastal evolution at inlets that connect the ocean to a lagoon or bay. Coastal inlets are narrow water bodies connecting estuaries, lagoons, and bays to the ocean. Inlets serve as conduits for commercial and recreational navigation, and their channels are typically dredged and maintained for this purpose. Also, the flow through the inlet, primarily due to tidal motion and river input, is the main mechanism for water exchange in the lagoon that ensures a decent water quality. Sediment infilling of an inlet channel and the resulting reduction in the cross-sectional area reduces the water exchange between the lagoon and the sea causing deterioration of the water quality. Models that can accurately reproduce the morphological evolution of inlets and the effects on lagoons and bays are highly useful tools for understanding and managing inlet/lagoon systems. The lagoon and coastal hydrodynamic, waves and currents interactions, sediment transport and the resultant morphological changes are some of the complex processes that in regional scale presents high computational demands to be modeled which is one of the main challenges of this approach.