Technical feasibility of a large-scale land reclamation

The expansion of human and economic activities together with the increasing pressure due to natural causes and the limited availability of land in the Dutch coastal provinces require examination of coastal extension. Therefore, five alternatives of land reclamation are designed to accommodate industrial activities and an offshore airport near the Port of Rotterdam. Three alternatives are located southwest of the Maasvlakte and two alternatives north of the approach channel of the Port of Rotterdam. Tidal elevation is simulated for each alternative with Delft3D, 2DH-mode (depth-averaged), to indicate the impact of each alternative on the tidal flow along the Dutch coast and hydrodynamics in the approach channel. Appraisal of these results indicates that the alternative of a Peninsula attached to the Maasvlakte pointing in southwest direction has the least impact on the tidal flow and is further examined to indicate the impact on the wave climate and morphology. The impact of the land reclamation on the wave climate is noticeable in the area enclosed by Scheveningen, Goeree Overflakkee and the peninsula. With normal wave conditions, the impact at the coastline of Goeree Overflakkee is < 5%. The impact of the peninsula on morphology is examined by simulation with sediment transport. The short-term simulations are done with Delft3D, sed-online (Van Rijn 2004). The long-term simulations are done with Delft3D-Ram (Rapid Assessment of Morphology, where flow and morphological calculations are decoupled). Both simulations determine significant erosion at the west side of the land reclamation (due to contraction of the tidal flow) and relatively less erosion will occur west of Schouwen Duiveland and Goeree Overflakkee. It is expected that less sedimentation will occur in the approach channel of the Port of Rotterdam. The relative longshore transport, for short- and long-term simulations, is determined at three cross-shore transects, i.e. Hook of Holland, Scheveningen and Noordwijk. Integration of the mean total longshore transport over the transect length indicates an increase in longshore direction, which could indicate erosion along this part of the coastline. The land reclamation will have an impact on the silt transport along the Dutch coast. A rough indication of influence on the silt transport is examined, leading to the following crude estimates: Siltation in the area enclosed by the peninsula and Goeree Overflakke will increase by considering tidal storage, which leads to an increase of this tidal area with a factor 2. Siltation in harbour basins of the Port of Rotterdam may decrease slightly (10 to 20%) as the water entering the system will originate from deeper water at the North Sea. The reduction of the siltation may be of the order of 1 2 [Mm3/year]. Siltation in Eastern-, Western Scheldt and Wadden Sea may change slightly. Finally, it can be determined that the large-scale land reclamation may be a good solution for the long-term spatial problems in the coastal zone when considering the aspects examined and the simplifications used in this study. Most side-effects are small or can be compensated and are only located in the direct vicinity of the land reclamation. Other side-effects contribute positively to the coastal safety of the Dutch coast. Further detailed studies should indicate the long-term and large-scale effects on sediment transport and the effects on the area between the land reclamation and Goeree Overflakkee.Civil Engineering and Geoscience