Ecobeach Monitoring project Phase II : Year study

In order to protect the Dutch coast in an innovative way, the Ecobeach technique (vertical, passive drainage pipes that are regularly spaced on the beach) has been installed in Egmond. During the half-year study, an objective method (statistical model) has been developed to identify the natural behaviour of the beach and dune system in the test area, based on historical data of Coastal State Indicators deduced mainly from Jarkus data. The overall objectives of the year study are: (i) to improve the statistical model in order to make it able to describe seasonal patterns, (ii) to describe the long-term natural behaviour of the coastal system in the reference area, (iii) and to analyse the behaviour of the beach and dune system in the test area after installation of the Ecobeach modules, with respect to the spatial and temporal references, and then to identify potential effects of the Ecobeach system. Statistical regression models, including harmonic components to take into account cyclic patterns (sand bar migration, seasonal variations), have been set-up. Comparison between model outputs and observations, obtained after installation of the drainage system, enables the identification of potential effects of the drainage system. An increase of the MCL and MiCL volumes have been observed between 2006 and 2007 in the test and in the reference areas. The increase of volumes has been predicted by the model and is associated to natural causes (cyclic reappearance of the sand bar). In general, no significant trend break has been noticed in the evolution of Coastal State Indicators.