Sand transport dynamics after a foredune breach: A case study from Schoorl, The Netherlands

Near Schoorl in The Netherlands a gap was created in the foredunes during a nature development project in 1997. This resulted in considerable aeolian sand transport and allowed the sea to enter the swale valley behind the foredunes during storm events. From 1997 to 2002 a monitoring program was carried out and various data sets were collected. This study used a part of those data to investigate the effects of a foredune breach on sand transport dynamics. The main focus was on the aeolian transport of sediment through the gap in the dunes. After the breach calcareous beach sand was transported into the swale valley where exclusively decalcified sand was present. This enabled a study of the spatial aspects of transport based on six data sets of carbonate content that were collected during the 1997-2002 period. Grids of carbonate content were interpolated and analysed together with data on geomorphology, topography and wind characteristics. The results provided insight on the displacement speed of the deposition front of calcareous sand, the influence of transport barriers and the correlation of transport directions with wind data. In addition, the study led to the observation that the trend of increase of available digital data during the last two decades is significant in facilitating the study of sand transport at the landscape scale. This is encouraging given the fact that the practical use of existing sand transport models in this context remains limited.