Assessing socio-economic impacts of wave overtopping: An institutional perspective Jan Jaap Bouma a,b , Delphine François a,b, ⁎, Albert Schram d , Tom Verbeke a,c a Centre for Environmental Economics and Environmental Management (CEEM), Faculty of Economics and Business Administration, Ghent University (UGent), Tweekerkenstraat 2, 9000 Gent, Belgium b Section Economics of Infrastructures, Faculty Technology, Policy and Management, Delft University of Technology (TUDelft), Jaffalaan 5, 2628 BX Delft, The Netherlands c HUBrussel, Stormstraat 2, 1000 Brussel, Belgium d Faculty of Economics and Business Administration, University of Maastricht, Tongersestraat 53, 6211 LM Maastricht, The Netherlands ABSTRACT ARTICLE INFO Available online 5 May 2008 Keywords: Cost-Benefit Analysis Valuation Coastal defence Wave overtopping One way to address the assessment of strategies to control wave overtopping at seawalls and related coastal defence structures is to make use of Cost-Benefit Analysis. The institutional context in which Cost-Benefit Analysis takes place influences decisions on the types of values that are taken into consideration and the subsequent selection of valuation methods. We suggest to consider Cost-Benefit Analysis in a broad institutional framework when decisions are to be made on coastal defence strategies. It is argued that the institutional context provides the rules of the game on how a balance can be found between social, economic and ecologic functions of projects that protect societies against overtopping. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Overtopping occurs when waves run up the beach, revetment, seawall or breakwater and pass over the crest of the defence. The resulting flow is often termed ‘green water’ overtopping. The frequencies, volumes and velocities of these overtopping events substantially influence the safety of the defence and of people living, working or travelling close behind the defence structure. A second form of overtopping occurs when waves break on or seaward of the face of the structure and produce significant volumes of fine droplets. The major hazard related to this ‘spray overtopping’ is reducing visi- bility on coastal highways where the sudden loss of visibility may cause significant driving hazard (Allsop et al., 2003). The possible damage of a wave overtopping event depends on a large number of factors: the timing and intensity of the event, the presence of human settlements in the affected area, the income characteristics of the population, the amount of traffic, the presence and value of private property and companies, the level of investment in other infrastructure, the type of activities taking place, etc. Allsop (2004) identifies three types of hazards from direct wave and overtopping effects, namely - direct hazard to people (injury or death); - damage to property, operation and/or infrastructure in the area. The disruption of economic activities falls under this category; - damage to defence structures. The latter category may lead to failure of the defence, which in turn might cause flooding and thus also e.g. hazard to people or damage to property and infrastructure. Various measures can be taken to mitigate the effects of wave overtopping. Unless otherwise specified, we will use the term coastal defence to identify structures that protect against wave overtopping effects. Pettit (1999) uses the term as a generic name that includes coastal protection (protection of the land from erosion and subse- quent inundation), sea defence (protection of land from flooding) and tidal defence (sea defence upstream of a specified boundary). It in- cludes all forms of structural (engineering for flood defence/erosion protection) and non-structural (development planning in coastal areas) methods of protection from tidal erosion and inundation. Economic appraisal enables the comparison of differing options in order to identify those which provide overall best value for money. In the context of flood and coastal defence projects, Cost-Benefit Analysis (CBA) will normally be a significant factor on which schemes and scheme options will be selected (MAFF, 2001). One of the pre- requisites for sound Cost-Benefit Analysis is the existence of adequate valuation techniques, so that significant but unpriced effects can be included. Many studies have been carried out to identify the effects of flooding and value them in monetary terms. The socio-economic impacts of wave overtopping are less documented from a valuation perspective. The development of valuation techniques goes hand in hand with the increasing use of Cost-Benefit Analysis. Decisions on Coastal Engineering 56 (2009) 203–209 ⁎ Corresponding author. Centre for Environmental Economics and Environmental Management (CEEM), Faculty of Economics and Business Administration, Ghent University (UGent), Tweekerkenstraat 2, 9000 Gent, Belgium. Tel.: +32 9 264 34 78; fax: +32 9 264 35 99. E-mail address: Delphine.Francois@UGent.be (D. François). 0378-3839/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.coastaleng.2008.03.008 Contents lists available at ScienceDirect Coastal Engineering journal homepage: www.elsevier.com/locate/coastaleng