Flooding and London are not usually two words that go together. With the exception of some brief, occasional flash floods, the capital experiences little to no widespread flooding, even during the harshest of storms.
The Thames has not broken its banks since 7 January 1928. In that year, a record-breaking storm and the resulting flood killed 14, destroyed two bridges, flooded the House of Commons and even refilled the Tower of London’s moat, among other effects. Had Steel House (built 1937) existed then, the water would have almost certainly reached it.
This, together with a 1953 flood that brought the Thames within millimetres of breaking its banks, began the development of those odd, curved and shiny structures you can see near Greenwich—the Thames Barrier.
The Thames Barrier, rarely enough for British public projects, was well designed, long-lasting and affordable given what it was doing: £1.2 billion in today’s money in exchange for protecting a city with a GDP of over £500 billion. In principle, the design is simple - revolving gates open and close to maintain a safe water level for the Thames. However, factors that the 1980s planners would never have assumed would cause issues already are: climate change.
This one piece of vital infrastructure is protecting the entirety of London from potential disaster, and yet its utility is already waning. The EA is scrambling to improve upstream defences by 2050 as a maximum, but what happens if London does flood, and that 100-year event becomes a reality?
The unfortunate side effect of the Thames Barrier’s positioning is that, if it fails, the surrounding area will suffer from by far the highest flooding anywhere in London. Even now, Silvertown has the highest flood risk of any area in the city, not helped by the multitude of tunnels and low-lying, marshy land that surrounds it.
Flood, a 2007 box-office flop about a once in a century London disaster, might have slightly stretched the consequences: half the city’s population is evacuated or killed, every underground station is filled to the brim, and survivors make their way through a series of sewage and transit tunnels to safety.
While we’ll probably never have it this bad, severe flooding would impact much of central London. Sewers would backflow and it would probably take weeks for the water to drain away from the city. Thousands would be displaced temporarily, many permanently.
If such a scenario seems far-fetched to you, it certainly is not for insurance brokers and the Environment Agency. In its first 20 years of operation, the Thames Barrier closed 87 times. In the last 20 years, 121. Barely 40 years old, the EA is already questioning its future. With rising sea levels and evermore erratic weather events, serious considerations for a replacement barrier are being drawn up. It is constantly revising its “Thames 2100” strategy, usually to indicate that targets need to be reached more quickly than expected.
As far back as 2017, there are reports of insurance brokers increasing premiums for those living near the barrier by over 400%, with others who live on the river being refused insurance outright. Areas like Bermondsey have been deemed “uninsurable”.
It is, as a result, not very reassuring for Londoners to hear that, in its own report, the Environment Agency has deemed that the flood defence grant it receives will not be sufficient to sustain much of its infrastructure. Chronically underfunded, the EA is being attacked from all sides for effectively every aspect of its work, and we can only hope that flood defences are not an area where budget cuts take precedence over safety.