Task 7 has looked at improving the understanding of the relationship between individual components of a flood defence system and its overall performance.  This has resulted in the development of reliability analysis techniques, incorporating the knowledge on individual failure modes and interactions between failure modes that had been collated by Task 4, Task 5 and Task 6.

• A defence reliability analysis framework has been developed to support a range of decisions and different levels of complexity (feasibility, preliminary and detailed design level). 
  
  
• A software tool called RELIABLE has also been developed, which calculates the annual probability of defence failure for flood defence structures. 

These outputs are intended for engineers, scientists, researchers and specialist planners involved with the assessment and management of risks associated with flood defence structures.

Task 7 provided input to Task 8 (flood inundation models), Task 11 (a community’s vulnerability to flooding) and a Task 18 (framework for long-term planning of flood risk management strategies).

In addition, the work under Task 7 was further enhanced by applying the software tool to pilot sites relating to the Thames (Task 24), Schelde (Task 25) and German Bight (Task 27).

Key words:  failure probability, flood defence failure, flood defence structure, fragility, flood risk analysis, uncertainty analysis, probabilistic design, reliability analysis