Thames estuary - Establishing a robust flood system model to support engineering investment decisions

The Environment Agency is currently planning its long-term approach to Flood Risk Management within the Thames Estuary. This is a significant and multi-dimensional challenge. Adapting and managing existing defences, barriers, gates and pumps as well as building new ones are likely to have a significant role as part of this future. This paper explores the initial development and first application of a system model capable of supporting a risk-based targeting of investment. The paper demonstrates how a regional system analysis tool – based on the RASP High Level analysis framework - can be used to provide an assessment of both flood risk and the performance of different response strategies under future scenarios. The practical issues explored in this paper include:
Data gathering – including hierarchical approaches to the use of data and the attribution of data uncertainties.
Defence performance analysis – how national scale and local analysis of defence failure can be integrated.
Quantifying the individual defence contribution to risk (within the context of over 480km of defences within the tidal Thames) The paper concludes with a practical insight to the use and utility of system models in the context of an active and complex decision making process.