Morphological monitoring of a shoreface nourishment nourtec experiment at Terschelling, The Netherlands

The morphological behaviour of a shoreface nourishment site is studied. The originally observed patterns in bar development before the nourishment are disturbed by the extra volume of sediment in the cross-shore profile. Attention is focused on the morphological development of the nearshore bars and troughs after the nourishment. After almost a year, the bar at the landward site of the nourishment showed a reversal in bar behaviour in comparison with the natural conditions as described by Ruessink and Kroon (in press). The bar was slightly moving landward and was growing in height, whereas a similar bar at this position within a non-nourished environment would move seaward and reduce in height. The bar at the seaward side of the nourishment is quickly adjusting itself to the situation before the nourishment. The bar behaviour after the nourishment is accompanied by a redistribution of the sediments over the profiles. The net amount of sediment losses in the nearshore area is negligible. This also means that the nourished volume of sediments is still available in the central part of the nourishment area. Longshore movements of the nourished volume are in the order of 400 m to the east over a period of about a year, and are not observed in the cross-shore profiles with a longshore spacing of 1000 m.