Decadal Scale Performance of Coastal Maintenance in The Netherlands

摘要

The Dutch government policy of "Dynamic Preservation" was implemented in 1990 with the strategic objective to provide sustainable safety and sustainable preservation of values and functions of the dune area. In the context of the implementation of the Dynamic Preservation policy, an active nourishment program was initiated to achieve the primary operational objective: preservation of the coastline not landward of its 1990 position. Earlier studies show that the strategic objective was not sufficiently operationalized to facilitate proper policy evaluation. The main objective of this paper is to evaluate, on an appropriate (time) scale, the effectiveness of the Dynamic Preservation policy in achieving its strategic and operational objectives. Given the strategic objective, appropriate is evaluation on a decadal time scale, viz. trends rather than incidental occurrences. As a result of the Dynamic Preservation policy the coastal stretch investigated in this paper — including two North Holland beach resorts, Egmond aan Zee and Bergen aan Zee - has been heavily nourished since 1990. An analysis of the morphological evolution of this coastal stretch, in terms of several quantitative state concepts, was performed prior to and post implementation of the nourishment program. The success of the nourishment program at affecting the specified physical features was confirmed, with the program being found overall effective but leading to questions pertaining to the efficiency of the nourishment program.