Jeroen Aerts on flood resilience for coastal megacities
Jeroen Aerts of the Institute for Environmental Studies in Amsterdam, coordinator of ENHANCE, explained how his 2014 study of New York City weighed levees, flood-proofing, insurance and beach nourishment.
Prof. Dr. Jeroen Aerts of the Institute for Environmental Studies (IVM) in Amsterdam coordinated the ENHANCE project. In this interview he discussed his paper “Evaluating Flood Resilience Strategies for Coastal Megacities”, published in Science in 2014 (volume 344).
The study used New York City as an example of an urbanised, vulnerable coastal megacity. Aerts argued that its lessons carry over to European cities facing storm surges and sea-level rise.
The strategies compared combined several kinds of measure:
- levees and storm-surge barriers;
- flood-proofing of individual buildings;
- insurance;
- “eco-engineering”, such as beach nourishment.
Two figures framed the problem. Without any measures, the study estimated flood losses in New York at 174 million USD a year. And when Hurricane Sandy struck, most of the households (80 percent) and small businesses (95 percent) it hit had no flood insurance.
Aerts drew three conclusions for long-lived measures, those meant to last more than 100 years. Their design has to hold up under changing conditions, since nobody knows what sea level will be in a century. They can be tied to ongoing maintenance, upgrading a barrier or dike as it is repaired rather than building everything at once. And financing them requires partnerships between many stakeholders, because no single public budget carries that cost alone.
That last point is the thread that ran through ENHANCE as a whole, as Aerts set out in his introductory interview. Uninsured shares after European floods are compared on the protection gap page.