Hess Opinions: An interdisciplinary research agenda to explore the unintended consequences of structural flood protection

Abstract

Abstract. One common approach to cope with floods is the implementation of structural flood protection measures, such as levees or flood-control reservoirs, which substantially reduce the probability of flooding at the time of implementation. Numerous scholars have problematized this approach. They have shown that increasing the levels of flood protection can attract more settlements and high-value assets in the areas protected by the new measures. Other studies have explored how structural measures can generate a sense of complacency, which can act to reduce preparedness. These paradoxical risk changes have been described as levee effect, safe development paradox or safety dilemma. In this commentary, we briefly review this phenomenon, by critically analysing the intended benefits and unintended effects of flood protection with two main examples, and then propose an interdisciplinary research agenda to uncover these paradoxical dynamics of risk.

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

“…This realization should result in programs that focus on flood management rather than control. Part of the solution, as 25 indicated by Di Baldassarre et al (2018), is to develop policies and educational programs that reverse, or at least keep from growing, the consequences of the levee effect. A comprehensive flood management system would include actions throughout entire catchments, with the goals of improving both socio-economic and ecological conditions.…”

“…The levee effect emphasized by Di Baldassarre et al (2018) is not the only unintended and undesirable socio-economic effect 5 of levees. Levees are usually built in tandem with dams and, in certain cases, retention structures that buffer peak flows (e.g., artificial floodplains or water holding structures) and modified channels.…”

“…Recently, Di Baldassarre et al (2018) pointed out that construction of flood-control levees may have unintended and undesired socio-economic consequences. They attribute this to the "levee effect": Once levees are built to protect assets such as homes, farms, and commercial buildings from flooding, the sense of security they provide results in more assets being located behind the levees.…”

“…These realities are often not conveyed well to the stakeholders who live behind the levees (e.g., Ludy and Kondolf, 2012). Therefore, Di Baldassarre et al (2018) propose a research agenda to "significantly improve our understanding 15 of the unintended effects of flood protection" with a special emphasis on human behaviour. While this research agenda is important, our experiences show that the levee effect is not the only negative impact of levee construction, but that a whole suite of unintended socioeconomic and ecological consequences within and beyond the river systems are the unavoidable result of levee construction and maintenance (Fig.…”

“…Acknowledgements. This commentary was inspired by an earlier opinion paper on unintended consequences of structural flood protection by Di Baldassarre et al, 2018. Their focus on socio-economic aspects motivated us to extent the topic on unintended ecological aspects.…”