Depending on sediment supply, two types of simulations are carried out: calibrated simulations, which assume that the amount of sediments in the future will be equal to those in the present situation and extreme simulations, which assume an acute shortage in sediment supply. Two different future scenarios are investigated: the 'do-nothing' scenario, which assumes that no further engineering interventions will be performed on the coast and the 'detached breakwaters protected' scenario, with the first breakwater introduced in 2011 and the second in 2026. The present time shoreline position, from which future situations are predicted, was obtained using LIDAR data acquired in 2011.

The shoreline evolution is predicted, for various decades, using the GENESIS model. The study area extends from south of the Costa Nova village southwards to Mira.

In this work, the impact of those two detached breakwaters on the down-drift coast is investigated. In an attempt to reverse the present erosional trend, a coastal defense scheme involving two detached breakwaters was introduced in a phased manner. Some locations, such as the Vagueira region, are especially vulnerable. The Portuguese West Coast is facing severe erosion problems that threaten both the population and the immediate seaside properties.

Breakwaters switch