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