Integrated monitoring was conducted to evaluate the result of nature development actions to increase the biodiversity. During the first year, the natural fluctuation of the piezometric level has been determined based on existing data and newly gathered data. From these data, the groundwater table classes following a classification, developed in The Netherlands, have been deduced. However, the result does not correspond with the observed vegetation. To predict the natural habitats and ecosystems in the coastal dunes of Belgium, a new classification adapted to natural conditions in the area is required. Advantages of existing approaches are integrated in the classification, combined with new elements, to represent the relationship between groundwater regimes and ecosystems. This new classification, consisting of 4 codes, provides information about the mean high water table depth, the mean low water table depth, mean spring water table depth and whether inundation can take place or not. It also gives an indication of the variability of the seasonal fluctuations of the water table and the importance of the fluctuation of the water table between years. With this new classification, a fine breakdown by ecotypes is possible. The new classification has been applied to the existing data in the study area.