ABSTRACT
Sand nourishment is an increasingly adopted measure for the sustainable management of coastal environments (i.e. beach and dune protection, restoration for short-term emergencies (storm induced erosion) and long-term issues (chronic erosion and RSLR effects)). Nourishments near tidal inlets are neither easy to sustain nor well-established. The application of numerical models may support the planning of nourishments. More efficient nourishment schemes can be implemented by analysing different nourishment strategies and therefore the model results support to reduce the failures and costs by assessing the environmental/economic implications (Capobianco et al., 2002). In the European perspective, the sand nourishment is mainly applied based on three objectives, 1). improving the coastal stability, 2). improving the coastal protection and 3). increasing the beach width (Hamm et al., 2002). Specifically, nourishment application is to maintain the coastline position according to the Dutch coastal policy of 1990 (Anonymous, 1990). Thus, the sand nourishment is extensively applied on the Dutch Coast (i.e. shoreface and beach) to maintain the coastline position (~6 Mm3/year since 1991) (Hanson et al., 2002). The shoreface nourishment acts as a reef with a lee-side effect shoreward of the nourishment area (Van Duin et al., 2004). This ultimately helps to a sustainable development of the beach area leading to net gain of sediment. Grunnet et al (2004 and 2005) used a numerical approach (Delft3D) to investigate the behaviour of the shoreface nourishment on the barrier island of Terschelling. Results of their 2DH approach suggested the same dependency on the spatial scale morphodynamics as in case of the 3D approach. Recently, sand nourishment has been investigated to compensate ‘sand hunger’ in the Eastern Scheldt of the Netherlands due to construction of the storm surge barriers (Camille, 2010; De Ronde et al., 2009; Escaravage et al., 2009). Camille (2010) analysed the possible morphological changes on Galgeplaat (i.e. an intertidal area) based on the bathymetric surveys and Argus video images and that implies positive effects of the nourishment. To date, more efforts have investigated nourishment to mitigate the chronic erosion of coastlines and little is known on the effect of intertidal areas. RSLR results in additional sediment demand on the intertidal areas of tidal basins to follow the increased MSL (see Chapter 4). Thus, the additional supply of sediment into the basin has to be the result of strong erosion of adjacent coastlines and ebb-tidal delta. The efficacy of nourishing ebbtidal delta to mitigate these RSLR induced erosive impacts on ebb-tidal delta itself and adjacent coastlines and to fulfill the RSLR induced sediment demand of the intertidal areas are investigated applying the 2DH modelling approach of Delft3D.
