A Monte Carlo-type random sampling, modelling approach has been used to improve London’s flood defences.
Southampton University and the Environment Agency (EA) have developed a tool that can more accurately predict when the Thames Estuary flood defences, including the Thames Barrier, will need to be closed.
The flood defence system protects more than 1.4 million people and £321bn worth of homes.
Due to climate change the barrier is being closed more frequently. However, closures of the defences need to be kept to below 50 a year, to allow adequate time for maintenance and not overstrain the system.
Operators can use the tool to plan routine and largescale maintenance, and upgrade schedules. The forecasting has already indicated that the flood defence system will need to be raised higher by 2050 and not 2065 as previously thought.
The tool can help plan for future scenarios and consider the effects of sea level rise, tidal cycles and storm surges, and potential shifts in the flows of river water. It uses a modelling approach used in engineering and other sectors that relies heavily on random sampling like rolling a dice repeatedly, hence why it is dubbed ‘Monte Carlo’ after the area in Monaco known for gambling.
Testing scenarios
Dr James Brand from the EA said: “This tool has provided us with vital new evidence to inform our strategic planning for managing London’s tidal flood risk.
“It helps us to test different scenarios for managing the flood defence system and allows us to make better-informed decisions when setting deadlines for implementing improvements to the tidal flood defence system.”
Professor in Ocean and Earth Science at Southampton University, Ivan Haigh, added: “Around the world there are more than 50 storm surge barriers in operation, protecting tens of millions of people and trillions of pounds of property and infrastructure.
“However, with climate change, surge barriers are closing increasingly often, and closures are now occurring in months when they typically have not occurred in the past. Increased use of surge barriers in the future has critical implications for barrier management, maintenance and operation.
“Working closely with staff in the EA, we have produced a flexible tool that can estimate how much more often and which times of the year operators are likely to have to use their barriers.
“Working with the EA, and other barrier operators in the Netherlands and US, we have considered the implications of this on future barrier management and maintenance, and identified when in the future barriers might have to be upgraded and replaced.”
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