Multifunctional Flood Defences

Multifunctional flood defences are flood protection structures that are meanwhile being used for other purposes, such as housing. In order to function as a flood defence (i.e., prevent flooding) these structures have to be part of an entire system, like a dike ring. This means that the maintenance, inspection, control and the stipulation of safety levels have to be organized.

The combination with other functions than flood protection in a flood defence becomes an interesting alternative if necessary improvement of existing flood defences conflicts with other functions, like housing. Multifunctional flood defences can also become a relevant option for ongoing urbanisation in built-on areas. Integration of functions could also be interesting for dividing costs between several parties. Governance issues related to multifunctional flood defences, however, are very delicate because of possible conflicts in responsibilities.

Examples of these secondary functions are: transport, housing, shipping, agriculture, nature and recreation. A dike with a road on top, for instance, is a multifunctional flood defence. Houses with water-retaining walls, or parking garages in dunes are other examples.

A research programme of Technology Foundation STW studies the 'integral and sustainable design of multifunctional flood defences'. Twelve researchers and four PostDocs aim to gain insight in the behaviour of the multifunctional flood defences during extreme storms. New principles of risk assessment methods will be developed and technology for multifunctional and flexible flood defences will be integrated into the development of urban and rural landscapes. Furthermore, new governance and asset management principles will be developed for multifunctional flood defences in the design and management phase. New physical and safety knowledge will be integrated into the design of multifunctional flood defences. More information about the research program can be found at www.flooddefences.nl.

Involved research institutes are: Delft University of Technology, Wageningen University and University of Twente. Potential users exist of regional authorities (water boards a.o.), national authorities (delta programme and ministries), knowledge institutes (Deltares a.o.) and companies (Dura Vermeer, Arcadis, HKV).

Within the Department of Hydraulic Engineering five researchers are involved in the programme: Xuexue Chen (wave overtopping and loads on buildings), Kathryn Roscoe (probabilistic models), Flora Anvarifar (uncertainty, adaptability and robustness), Wouter ter Horst (optimal and robust design) and Mark Voorendt (structural assessment).

Multifunctional quay in Zaltbommel   

Cross section of a combined quay and parking garage in Zwijndrecht

Cross section of a house in Dordrecht, combined with a flood protection function