Author(s): Sergio Salazar-Galan; Felix Frances

Linked Author(s): Félix Francés

Keywords: Flood risk; Hazard; Coping capacity; Management measures; Risk reduction

Abstract: Within the flood risk management paradigm, there are several measures that contribute to risk reduction either by reducing hazard and/or vulnerability. Classic engineering measures such as dams or dykes are the subject of much debate, mainly because of their impacts on the natural flow regime of aquatic ecosystems. On the other hand, nature-based measures have been positioning themselves as a compromise solution as they are multifunctional and provide a variety of ecosystem services beyond risk management. The disadvantage of these measures can be their implementation, especially in the case of watersheds with high degrees of anthropogenic alteration and high population density in risk zones. In these cases, warning and response systems gain special relevance, which must function very well so that, in the face of an imminent flood, the decisions taken are appropriate and the response is effective. In the light of the above, the aim of this work is to analyse, in a real case study of the Spanish Mediterranean, the effect on risk reduction of the consideration of a set of management measures covering three typologies: engineering measures (dams); nature-based solutions (forest restoration); property flood resilience or property level protection (removable door barriers). To this end, a comprehensive methodology for risk analysis under current conditions has been structured for subsequent application by introducing the above-mentioned management measures. The methodology introduces the use of stochastic storm modelling, hybrid distributed hydrological modelling, hydrodynamic modelling, and an ex-ante damage evaluation model. The results show that despite achieving a reduction of around 50% of the Annual Expected Damage (AED) with the use of measures that reduce the hazard component of risk such as dams or forest restoration, the AED remains at a high magnitude. This result highlights that the intervention of the hazard variable alone is not enough. When analysing the effect of removable door barriers (an expression of the coping capacity and resilience), the AED is reduced by around 20%. This shows that adequate response capacity is a relatively effective complementary risk management measure. Finally, the proposed methodology shows great potential for application in the prioritisation of management measures on a sound scientific basis.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221841

Year: 2022