279 



The wave heights will change. To predict the changes in wave height 

 it is necessary to know the morphological changes first. 



The dune coast line will retreat by 80 to 150 meters . 



The sedimentation in the Wadden Sea will increase and probably keep 

 pace with this sea level rise, so mean water depth and intertidal area 

 will probably remain constant. 



The salt intrusion via rivers and subsoil will increase. During 

 summer the amount of fresh water needed for flushing of the polders 

 will increase by about 10% . 



The water management of the Netherlands will have to be adapted. 

 Large areas that now drain naturally by gravity will not do so in the 

 future and large pumps will have to be installed. 



The ecological systems will be impacted. Intertidal area in the 

 Eastern and Western Scheldt and valuable dune area along the coast 

 will diminish. The ecological value of these area will be lost. 



The extra costs to raise our defenses against high water and to adapt 

 our water management system will be about 10 billion guilders 

 (5 billion U.S. dollars). 



References 



de Ronde, J.G. (1983). "Changes of relative mean sea level and of mean 

 tidal amplitude along the Dutch coast," in Proceedings of the NATO 

 Advanced Research Workshop Utrecht. Seismicity and Seismic Risk in the 

 Offshore North Sea Area . A. R. Ritsema and A. Gurpinar, editors. 



de Ronde, J.G., and De Ruijter, W.P.M., editors (1986). 



"Zeespiegelrijzing, worstelen met wassend water," GWAO-86.002, 

 Rijkswaterstaat, Tidal Waters Division, The Hague, The Netherlands (in 

 Dutch) . 



Gornitz, V., Lebedeff, S., and Hansen, J. (1982). "Global sea level trend 

 in the past century," Science, 215, 1611-1614. 



