Civil Engineering Works versus Self-protection measures for the mitigation of floods economic risk. A case study from a new classification criterion for Cost-Benefit Analysis.

Abstract

The application of classical cost-benefit analysis to flood risk mitigation measures can be improved by incorporating new comparative parameters, such as the risk-cost ratio, which is defined here for the first time. In addition, applying these analyses not only to the typical public structural measures (dams, dredging, flood storage reservoirs, transverse drainage works), but also to non-structural measures and self-protection (improving housing resistance to flooding, insurance policies), broadens the range of active risk management options. Last two categories are measures with lower initial investment (thus reducing costs) and visual and environmental impact, making them compatible with the EU Water Framework Directives and flood risk management. All these analyses of economic flood risk have been tested in a small Spanish village in the central Iberian Peninsula. For different flooding scenarios, new proposed RCR criterion allow us a rapid and effective quantification of the efficiency of each of the measures, allowing the ordered classification of the same; as well as the weighting of the results according to the particular needs of the decision makers (prioritizing well the reduction of damages, or the necessary economic investment). Thus, the RCR reveals itself as a powerful tool for flood risk management.