Author(s): Eduardo Garcia Alonso; Beatriz Tejerina

Linked Author(s):

Keywords: Nature-based solutions (NBS); Sustainable Urban Drainage Systems; Sponge City; Cost-benefit analysis

Abstract: NBS encompass a wide range of technologies and infrastructures that are gaining traction in urban water management, usually as a complement to standard drainage systems. Although NBS have been tested in many cities, there is still resistance to their use, especially in developing countries, often citing high costs (both construction and maintenance), the need for large urban areas, and uncertainty about their flood mitigation effects. This paper addresses the latter issue by providing a methodological framework to quantify the impact of a NBS package on flood risk reduction in a given urban area. The method is intended for scoping and pre-feasibility analyses, thus circumventing a cumbersome and data intensive modeling of each infrastructure. The method entails seven steps including the extraction of key urban features from the most flood prone areas, the setting of implementation rates of an NBS package along with its costing, and the estimate of its on flood reduction as proxied by the peak flow for any given return period. The peak flow accounts for NBS by means of an ad hoc program developed for this specific purpose featuring a hydrological model for the upper and the lower catchment. The former accounts for hydrological upstream processes and retention basins (if any) while the latter accounts for the whole NBS package. Altogether, this framework allows a quantitative estimate of the flood risk reduction imputable to NBS along with a basic cost benefit analysis.

DOI: https://doi.org/10.64697/978-90-835589-7-4_41WC-P2045-cd

Year: 2025