Performance-based management of flood defence systems

Abstract

Performance-based asset management is a process of managing an infrastructure system in order to optimise its behaviour when evaluated against specified objectives. It enables prioritisation of investment in flood defence infrastructure construction, inspection and maintenance. It is risk-based, in that costs of alternative interventions in the flood defence system are weighed against their benefit in terms of flood risk reduction. It also has to take account of the multiple objectives for flood management, including economic efficiency, the environment and safety. A new approach to representing the performance of a flood defence system has been developed by the authors. The flood defence system is represented hierarchically providing an overview of system performance as well as more detailed insights into the performance of specific assets. Performance is measured by a set of performance indicators held in a database. These performance indicators are projected through value functions reflecting organisational objectives and regulatory standards and are merged to generate a figure of merit for the system and each subsystem. The figure of merit forms the basis for asset management decisions. Uncertainty in the available evidence is represented and propagated through the hierarchy, providing a commentary on sources and implications of uncertainty. A case study for the flood defence system surrounding a town demonstrates how the methodology provides insights into system performance and can be used to explore different asset management decisions.