Flood risk reduction - structural measures and diverse strategies

Hurrican Florence. Credits NASA
Hurrican Florence. Photo: NASA

In order to make cities around the world flood-resistant, we will have to invest in a wide range of strategies. Peter Driessen and Dries Hegger from Utrecht University have written an editorial describing three lessons for a ‘safe-fail’ flood policy; a system that is designed to fail safely from time to time.

Floods are the most common type of natural disaster, and they will become more common - and more severe - over the next few decades due to urbanisation and climate change. Flooding can cause fatalities and serious economic damage, and in the worse cases they can even result in social disruption, as was the case during hurricane Florence, which hit the southeaster coast of the United States on 14 September.

Building stronger and higher dikes - what experts call ‘structural measures’ - is not enough to prevent flooding, and it is also extremely expensive, especially in developing countries that have to start from the ground up. A wide range of strategies are therefore needed, including an intelligent spatial plan, flood-resistant construction, and having an adequate disaster management and recovery plan on hand when floods strike. Realising all of these elements will require a massive administrative undertaking.

From European to Global

Professor Peter Driessen and Dr Dries Hegger, both affiliated with Utrecht University’s Copernicus Institute of Sustainable Development are the coordinators of the STAR-FLOOD project (2012-2016) financed by the European Commission. In an editorial published in the prestigious journal PNAS, they and their Polish colleagues argue that the results of this European-focused project are also relevant at the global level. The lessons learned could therefore be applied to improved flood management policies in countries around the world that are even more vulnerable to flooding than most of the countries in Europe.

Geographic centers of floods from 1985-2010.

Three lessons

In their editorial, the researchers describe three of these lessons. First, governments will have to implement a wide range of strategies to deal with the problem. No country can allow itself to rest too heavily on a single strategy. However, the choice of strategies will have to take the country’s physical situation and existing policy context into consideration. Second, more diverse parties will have to be involved in formulating flood policies, including private actors and citizens and reinforcing the capacity of all levels of government. This will not only raise awareness of the risks among citizens and businesses, but will also offer concrete guidelines for further action. Finally, the authors recommend expanding the social debate about the acceptable risks posed by flooding. This debate will have to be accessible to everyone, so that stakeholders can contribute to deciding which risks are acceptable, and who should be held accountable for managing them.

A safe-fail system

The authors conclude that there is no magic bullet for managing the risks of flooding, but an intelligent expansion of strategies that use the input - and ask for permission - from public and private parties and citizens can make a vital contribution to enhancing flood resiliency. Such a resilient flood management policy would not only focus on absolute security, but rather be based on a ‘safe-fail’ principle: a system that is designed to fail safely from time to time.


Kundzewicz, Z.W., D.L.T. Hegger, P. Matczak, P.P.J. Driessen (2018). Flood risk reduction - structural measures and diverse strategies, Proceedings of the National Academy of Sciences (PNAS), vol. 115 (48), pp.