(Stefan Rousseau/PA)
(Picture: PA Wire)London urgently needs to adapt to the rising threat from flash flooding, which is being supercharged by climate change.
The thunderstorms this week should remind us that we need to act urgently. Just over a year ago, the capital got relatively lucky. Two major episodes of torrential rainfall inundated more than 1000 homes and businesses.
More than 1000 homes and businesses were inundated and transport networks disrupted across 24 boroughs, with some places receiving more than 80 millimetres of rain within a few hours, equivalent to almost twice a typical month’s total.
As bad as last summer’s flooding was, London was relatively lucky. With a growing number of basement dwellers, the sudden flooding could have caused deaths, particularly if it had occurred at night.
London must learn from the tragic drowning of 11 people in basement flats when Hurricane Ida drenched New York City last September.
Incredibly, London’s authorities do not have a list of basement properties so cannot provide advance warning to those who are most vulnerable from extreme rainfall. Creating a database of basement properties was one of the recommendations of a group that was set up by London Councils and the Greater London Authority after last year’s flash floods.
It also called for further upgrades of London’s drainage system, many parts of which are Victorian in age. The new super sewer could help to manage heavier rainfall, but only if our drains can cope with the higher volumes of water.
London has too many impermeable roads and other man-made surfaces, and not enough places where rainwater can sink below the surface. London also needs better maps that allow a clearer indication of where flood waters are most likely to pool due to topography and poor drainage.
But the most important action is for local and central government to treat the risks from flash flooding more seriously.
The review by London Councils revealed that there is a lack of leadership and coordination among the many public and private sector organisations that all need to work together to manage the risk of flash flooding. Central Government has also been slow to recognise the threat, even though it was surface water that was largely responsible for more than £3 billion in damage during the UK’s costliest floods in summer 2007.
Scientists have been warning this summer that heavy rainfall is increasing in intensity and frequency because a warming atmosphere can hold more moisture. London must confront this trend, which will continue over the coming decades until the world’s greenhouse gas emissions effectively reach zero.
