Integrating hydraulic and economic analysis for selecting flood protection measures in the context of climate change

In order to protect our societies from damaging impacts of climate change (floods, heat waves, droughts...), the most cost-effective adaptation strategies must be selected among a wide range of options (including structural and non-structural protection measures). The Belgian national project “ADAPT” aims to provide guidance for this choice by developing a decision-support system (DSS) for the selection of protection measures against increased risk resulting from climate change, and more specifically from floods. The DSS is based on a combination of cost-benefit analysis (CBA) and multicriteria analysis (MA), taking into consideration hydraulic, economic, social and ecological indicators. For the purpose of demonstrating the relevance and efficiency of the DSS, the approach is applied for two case studies located in the two main Belgian river basins (Meuse and Scheldt). Within this global framework, the present paper covers the description of the hydrodynamic modeling component and the economic analysis, focusing on their interactions and on their integration within the DSS. The paper also details the case study of the Meuse Basin (river Ourthe), for which the hydraulic simulations are conducted by means of the two-dimensional numerical model WOLF 2D, based on a finite volume scheme and entirely developed at the University of Liege. High resolution Digital Surface Models and geographic database are exploited, enabling to represent streets, buildings and parcels individually. Relevant damage functions are validated and refined based on the analysis of four recent major flood events, for which a relationship may established between simulated local water depths (and possibly velocities or flow duration) and actual damage costs. Consequently, the combined hydrodynamic and economic analysis described in the paper may be judged as a valuable tool for assessing the effectiveness of specific flood protection measures.