Assessment of nature-based flood defences' implementation potential: development and application of a game theory based method

Nature-based flood defence (NBFD) by means of vegetated foreshores is an innovative flood protection strategy. In contrasts with traditional hard structures it combines nature and flood protection functions and employs natural dynamics. Introducing such an innovation into actual flood protection projects requires not just proper understanding of the physical aspects of the approach. Equally important is the understanding of governance implications as NBFD decision-making implies involvement of different actors and actor interactions and requires alternative governance arrangements to enable implementation. Moreover NBFD implementation is far from self-evident; in fact most of the time traditional solutions are preferred. In this report we look into the actor interactions that are associated with NBFD and aim to improve understanding of NBFD implementation in flood defence projects. For that purpose we develop and apply a game theory based research approach. The objective is to: 1) systematically describe actor interactions in NBFD decision-making and the benefits of potential actor coalitions in NBFD projects; 2) identify exemplary NBFD games; and 3) understand solutions to the NBFD games and factors that may foster NBFD implementation. The approach is applied it three Dutch NBFD case studies: the Sand Engine, Markermeer dikes and the Afsluitdijk.