Thames Barrier future closure numbers tool

How adaptive planning approaches are being used to prepare the Thames Estuary for rising sea levels and changing river flows.

Thames Estuary 2100 – Projections of future Thames Barrier average annual closure numbers

2 Ocean and Earth Science, University of Southampton

The Environment Agency collaborated with Professor Ivan Haigh from the University of Southampton in 2021 to 2022 to create a tool to model projected future annual closure numbers of the Thames Barrier. The Thames Estuary flood defences, including the Thames Barrier, protect over 1.4 million people and £321 billion worth of residential property in London and the wider estuary (Environment Agency, 2021). To make sure that the Thames Barrier continues to operate reliably, the number of closures needs to be kept at or below an average of 50 per year to allow sufficient time for maintenance.

The projection tool that the team developed uses a Monte-Carlo modelling approach. It simulates a range of possible outcomes to predict minimum, maximum, and average projections for numbers of future barrier closures. As a result, the tool provides a more comprehensive understanding of future closure numbers which allows planners to consider not just sea level rise but also the effects of tidal cycles and storm surges, forecasting improvements, and even potential shifts in fluvial flow.

The level of detail provided by the projection tool enabled the Thames Estuary 2100 Plan (TE2100) to make more informed decisions about critical deadlines. For example, the tool’s insights led to an adjustment of the first defence-raising deadline for London from 2065 to 2050—15 years earlier than initially planned. This major shift reflected not only updated climate data, but also the anticipated impact of inter-annual tidal cycle peaks on closure frequency.