Just Cerfing Vol. 7, Issue 8, August 2016 Volume 5, Issue 3, March, 2014

Previous Page Table of Contents Next Page Soft Engineering vs. a Dynamic Approach in Coastal Dune Management: A Case Study on the North Sea Barrier Island of Ameland, The Netherlands Bart De Jong†, Joep G.S. Keijsers‡, Michel J.P.M. Riksen‡*, Johan Krol§, and Pieter A. Slim† † Alterra, Wageningen University & Research Centre 6700 AA Wageningen The Netherlands ‡ Soil Physics & Land Management Group Wageningen University & Research Centre 6700 AA Wageningen The Netherlands Natuurcentrum Ameland 9163 ZM Nes Ameland The Netherlands Dynamic coastal management, therefore, did not reduce coastal safety. ABSTRACT Dunes act as flood defenses in coastal zones, protecting low-lying interior lands from flooding. To ensure coastal safety, insight is needed on how dunes develop under different types of management. The current study focuses on two types of coastal dune management: (1) a “soft engineering” approach, in which sand fences are placed on the seaward side of foredunes, and (2) “dynamic coastal management,” with minimal or no dune maintenance. The effects of these management styles on dune formation are examined for two adjacent coastal sections of the North Sea barrier island of Ameland, The Netherlands, where dynamic coastal management was introduced in 1995 and 1999, respectively. For each section, we analyzed cross-shore profile data from 1980 until 2010, deriving dune foot position, crest position, crest height, and foredune volume for each year and analyzing the situation before and after the change in management. We further assessed the effect of the management regime on dune vegetation. Other factors that could influence dune development were also taken into account, such as beach width and shape, water levels, wave heights, and nourishments. Results show that implementation of dynamic coastal management did not directly affect the volume of the foredune. Growth was occasionally interrupted, coinciding with high-water events. In periods between erosive storms, dune growth rates did not show a significant difference between management types (p = 0.09 and 0.32 for sections 1 and 2, respectively). The main effect of the change was on vegetation development. 30 § ADDITIONAL INDEX WORDS: Coastal defense, storm surges, coastal dune development, aeolian sediment transport, vegetation development. INTRODUCTION Coastal zones are of strategic importance in Europe. Almost half of the population of the European Union (EU) live within 50 km of the oceans and seas, and many vital economic, social, environmental, and cultural activities take place there. This leads to intense competition for the limited space along Europe’s estimated 89,000 km of shoreline (Ciavola and Stive, 2012). In coastal zones, dunes act as ‘‘soft’’ ﬂood defenses, protecting low-lying interior lands against ﬂooding. To ensure coastal safety in the future, insight is needed on how these soft ﬂood defenses are likely to develop under various types of management (Bochev-Van der Burgh, Wijnberg, and Hulscher, 2009, 2011). Dunes are of particular importance along the coast of The Netherlands. Here, in addition to coastal defense, they contribute to various ecosystem services such as drinking water supply, recreation, and nature conservation (Arens, Jungerius, and Van der Meulen, 2001; Bochev-Van der Burgh, Wijnberg, and Hulscher, 2009, 2011; Braat et al., 2008; De Groot et al., 2012). The Dutch have traditionally intensively managed their coastal zones. Two main strategies are distinguishable in Dutch coastal dune management: The Just Cerfing Vol. 5, Issue 3, March 2014 Continued on Next Page 31

Just Cerfing Vol. 7, Issue 8, August 2016 Volume 5, Issue 3, March, 2014 | Page 30