Reviewing the Levee Effect: From Theory to Practice

Abstract

Ongoing development in flood-prone areas has intensified focus on flood-risk management strategies. Constructed flood protections, like levees, lead to a false sense of security. Resulting development behind levees paradoxically increases flood risk, referred to as the levee effect. In the 2010s, the nascent field of socio-hydrology revived levee effect research, extending its use as a descriptive and analytic framework for empirically understanding flood-risk–development dynamics. We systematically reviewed the evolution, applications, and leading edge of the levee effect between 2015–2024. From 62 peer-reviewed articles, we found that studies primarily assessed flood risk and risk perceptions (n = 31; 50%), with economic, policy, and vulnerability assessments as emerging areas. We identified three gaps. First, simply identifying the existence of a levee effect fails to advance practical solutions. Second, analysis of the political economy and long-term economic impacts (i.e., weighing costs of maintaining levees versus relocation) is underdeveloped. Third, most studies examined adaptation (e.g., raising home elevation) and mitigation (e.g., improved drainage) separately, but comprehensive flood risk management planning considering both together is lacking. Under the urgency of climate change, the levee effect offers a framework for examining complex social, economic, and political factors that make communities vulnerable to floods.