Figure 3.2 Failure tree for a typical temporary or demountable flood protection
system
An extensive risk analysis of composite flood defences carried out as part of the Kampen
Flood Defences scheme in Netherlands (Directorate General Ministry of Public Works and
Waterways, 1997), showed that the risk of occurrence each of the three failure modes in
Figure 3.2 are as follows:
Risk of failure by overtopping or excessive seepage through a closed defence 89%
Risk of failure due to insufficient strength or stability 1%
Risk of failure due to non-closure of defence 10%