Communicating (nature‐based) flood‐mitigation schemes using flood‐excess volume

Abstract

As interest mounts in nature-based solutions (NBS) for flood mitigation as complementary options to civil-engineering measures, possible flood-protection strategies have become more diverse and hence complicated to assess. We offer a straightforward and educational protocol targeted for effectiveness analysis and decision making involving stakeholder participation. It is based on the concept of flood-excess volume (FEV), the volume exceeding a threshold and generating flood damage, and explores what fraction of FEV is reduced, and at what cost, by particular flood-mitigation measures. Quantification and interpretation of cost scenarios are facilitated using a graphical display that is easy to understand and encapsulates concepts of flood magnitude, FEV and protection-measures efficacy. It is exemplified for two recent extreme-flood events on the River Calder in Mytholmroyd (Yorkshire, United Kingdom) and the River Brague in Biot (Alpes-Maritimes, France). Each case has different flood-mitigation measures such as natural water-retention measures, tree planting, river-bed widening, or use of reservoirs and floods walls. Our straightforward protocol enables fast, quantifiable and easy-to-understand exploration of protection strategies using multiple measures, and in doing so highlights the issue of NBS scalability.

Floods in Provence-Alpes-Côte D'azur and Lessons for French Flood Risk Governance

“…The historical disaster analysis of the PACA region underlines the need for new policies to be put in place. As we observe in Le Moniteur (2020), the Architectural association of Côte d'Azur (Syndicat des architectes de la Côte d'Azur) are suggesting a new way of thinking linked to ooding risk starting with not rebuilding in the same locations again (or in the same manner) but rather adopt a BBB logic by strictly avoiding the areas identi ed as potentially ooded in the PPRi [7].…”

“…In addition, the retention ponds promised after the 2015 disaster were still missing in various locations and are now estimated to start functioning in 2023 (see France-Digues on 09/12/2019 [6]). Bokhove et al (2019) conducted several workshops with local citizens in 2018 at the River Brague in Biot, and they illustrate that residents asked for more ood retention measures. Furthermore, the CEREMA report (2019) illustrates that only 2% of the total population use the #MyPredict app which alerts population against ooding, underlining the need for better communication on the side of ood governance.…”

A Cost-Effectiveness Protocol for Flood-Mitigation Plans Based on Leeds’ Boxing Day 2015 Floods

“…The Manning coefficient used is C m = 0.04. Altogether this yields the following rating-curve correction, see also [18],…”

“…Hence, we continue with our FEV estimate of V e (h T = 3.9 m). In companion articles [17,18], we also determine the FEV for the Boxing Day 2015 flood of the River Calder in Mytholmroyd and for the June 2007 summer floods, of the River Don at Sheffield Hadfields, which caused widespread damage and in which three people died [19]. The River Calder forms the catchment south of the River Aire, flows predominantly eastwards and merges with the River Aire in Castleford.…”

Scientific evidence for ecosystem-based disaster risk reduction

“…Another set of articles highlighted the economic value of DRR, and compared the costs and benefits of ecosystem-based and engineered solutions (for example, ref. 18 ). Finally, a limited number of articles focused on the role of ecosystems in mitigating climate change effects.…”