A Contribution to the Understanding of the Óbidos Lagoon Dynamics

Óbidos lagoon is a small coastal system connected to the sea through a shallow mobile inlet. The lagoon that is the support of an important ecosystem, beyond a natural accretion tendency, common to these coastal lagoons, suffers from cyclic water quality problems related with the difficulties in renewing the water due to the closing of its inlet. Beyond these problems it is common to have strong coastal erosion in the lagoon margins with consequences for the safety of the local houses. In these occasions it is necessary to take emergency coastal protection measures in order to avoid the occurrence of major disasters. In order to try to understand the lagoon dynamics an integrated lagoon model capable to simulate the water quality and the sediment transport by the combined effects of waves and currents was implemented. In this paper the discussion of some of the results obtained is presented and discussed.