London floods will definitely get worse

LONDONERS LIKE To remind visitors that rain is actually less common than some sunny climates, despite the city’s reputation in bad weather. The total rainfall in Rome is increasing every year. It rains almost twice as much in New York City, and there are far more rainy days. In general, the British capital is gray, but quite dry, with predictable and mild weather.

It may have changed. On July 25, some parts of the city rained more than 5 cm in just a few hours. This is usually the amount of rainfall over a month. As a result, flash floods were generated. In eastern London, two hospitals told them to stay away from patients. One, Whipscross had to evacuate about 100 patients after a power outage. Hundreds of cars were stuck on a sudden river road, forcing 12 subway stations to close. The Docklands Light Railway’s Pudding Mill Lane station looked like a pool, with a few feet of water washing around the ticket walls. Even in areas far from rivers and floodplains, such as Hampstead, a fairly suburb of northern London, shopkeepers had to drive rainwater down the street.

Unlike the destruction caused by the floods that struck parts of Germany in early July, the damage is short-lived. Most of the closed stations were reopened the next day. So was the hospital. However, such incidents can become more common in the capital. A government survey on flood risk at the mouth of the Thames, released in February, shows that even if global warming is limited to 1.5 ° C, international goals are more likely to be overlooked. , Winter rainfall can increase by 59%. A particular problem is the Thames Barrier, which prevents tide floods from flowing back into the city. It has been closed only 10 times in 10 years since the construction was completed in 1981, but has been closed 80 times since 2010. The study predicted that “an annual sea level event is expected to be an annual event.”

This problem is exacerbated by the way London has evolved. For decades, the water table was artificially suppressed by the factory hitting it. Deindustrialization means that it has risen again since the 1980s. Also, thanks to planning rules to protect Greenfield Land, many new homes have been built in flood-sensitive areas, such as the mouth of the Thames and the River Lea Valley, where the 2012 Olympic Park is located. Between 2014 and 2017, the population living near the park more than doubled, from about 10,000 to 26,000. By 2031 it is expected to reach nearly 100,000. All that extra concrete means that the water is having a hard time flowing out.

“Everything is going well on the floodplain,” says Asif Din of construction firm Perkins & Will. “But are developers going to actually mitigate what they put on the land?” Architects can easily design and make individual buildings and real estate elastic (and elastic). Many do so). However, they are not responsible for the wider infrastructure. Instead, the risk of flooding is managed by a government agency patchwork quilt. Having a resilient office building isn’t very good if no one can reach it because the nearby roads are flooded, Din says.

Some improvements already in progress should help. A new “super sewer” will open in 2025 with the aim of strengthening existing systems dating back to the Victorian era. Floods cannot be stopped, but sewage must be prevented from flowing untreated into the Thames (or flushing drains). Beyond the Thames Barrier, outside the eastern part of the city, flood protection is improving. But none of them may be enough to keep up with the changing climate. The last flood in central London was in 1928. 14 people were drowned in Westminster. It may still happen again. ■■

This article was published in the UK section of the print version under the heading “Live by the river”.

London floods will definitely get worse

Source link London floods will definitely get worse

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