HESS Opinions: Socio-economic and ecological trade-offs of flood management – benefits of a transdisciplinary approach

Abstract

Abstract. In light of climate change and growing numbers of people inhabiting riverine floodplains, worldwide demand for flood protection is increasing, typically through engineering approaches such as more and bigger levees. However, the well-documented “levee effect” of increased floodplain use following levee construction or enhancement often results in increased problems, especially when levees fail or are compromised by big flood events. Herein, we argue that there are also unintended socio-economic and ecological consequences of traditional engineering solutions that need to be better considered, communicated and weighed against alternative solutions. Socio-economic consequences include reduced aesthetic and recreational values as well as increased downstream flooding risk and reduced ecosystem services. Ecological consequences include hydraulic decoupling, loss of biodiversity and increased risk of contamination during flooding. In addition, beyond river losses of connectivity and natural riparian vegetation created by levees, changes in groundwater levels and increased greenhouse gas emissions are likely. Because flood protection requires huge financial investments and results in major and persistent changes to the landscape, more balanced decisions that involve all stakeholders and policymakers should be made in the future. This requires a transdisciplinary approach that considers alternative solutions such as green infrastructure and places emphasis on integrated flood management rather than on reliance on technical protection measures.

Do We Know Enough to Save European Riverine Fish?—A Systematic Review on Autecological Requirements During Critical Life Stages of 10 Rheophilic Species at Risk

“…Multiple stressors, including environmental and anthropogenic impacts such as climate change, pollution, habitat fragmentation and degradation, contributed to a massive decline in aquatic biodiversity in the last century [1][2][3][4][5]. In this context, especially riverine fish species experience the greatest threat by river regulation and fragmentation due to barriers including weirs, dams and hydroelectric plants [6,7]. The latter can have detrimental consequences for fish populations such as preventing migratory species from moving between key habitats during their life cycles [8][9][10].…”

Enhancing the resilience to flooding induced by levee breaches in lowland areas: a methodology based on numerical modelling

“…However, this kind of defence presents several ecological (e.g. hydraulic decoupling between the river and its floodplain, loss of biodiversity, change in groundwater levels, and increase in greenhouse gas emission) and socio-economic consequences (Auerswald et al, 2019).…”

“…It is relevant to note that high-resolution DTMs can be exploited thanks to the availability of parallel 2-D codes; until a few years ago, traditional 2-D and 1-D-2-D models usually adopted a low resolution of the order of 50-100 m for flood-prone areas in order to reduce the computational times (Aureli and Mignosa, 2004;Aureli et al, 2005;Vorogushyn et al, 2010;Masoero et al, 2013;Mazzoleni et al, 2013;Huthoff et al, 2015).…”

Flood risk in a range of spatial perspectives – from global to local scales

“…It is likely that temporally varying connections exist between indices of climate variability and variability of the likelihood of destructive abundance of water. Blöschl et al (2017) noted no "consistent climate change signal in flood magnitudes" in Europe, while Di Baldassarre et al (2010) reported a similar finding for Africa. Blöschl et al (2017) found climate-induced patterns of change in observed flood timing in Europe, at the continental scale.…”

“…Blöschl et al (2017) noted no "consistent climate change signal in flood magnitudes" in Europe, while Di Baldassarre et al (2010) reported a similar finding for Africa. Blöschl et al (2017) found climate-induced patterns of change in observed flood timing in Europe, at the continental scale. They detected earlier spring snowmelt floods throughout northeastern Europe (warming-driven change), later winter floods around the North Sea and part of the Mediterranean coast (related to polar warming), and earlier winter floods in western Europe (reflecting advancement of soil moisture maxima).…”