An Integrated Approach to Flood Risk Management: A Case Study of Navaluenga (Central Spain)

Flood risk management decisions require the rational assessment of mitigation strategies. This is a complex decision-making process involving many uncertainties. This paper presents a case study where a cost-benefit based methodology is used to define the best intervention measures for flood-risk mitigation in central Spain. Based on different flood hazard scenarios, several structural measures considered by the local Basin Water Authority and others defined by engineering criteria were checked for operability. Non-systematic data derived from dendrogeomorphological analysis of riparian trees were included in the flood frequency analysis. Flood damage was assessed by means of depth-damage functions, and flooded urban areas were obtained by applying a hydraulic model. The best defense strategies were obtained by a cost-benefit procedure, where uncertainties derived from each analytical process were incorporated based on a stochastic approach to estimate expected economic losses. The results showed that large structural solutions are not economically viable when compared with other smaller structural measures, presumably because of the pre-established location of dams in the upper part of the basin which do not laminate the flow generated by the surrounding catchment to Navaluenga.