Overflooded Yongding river, after heavy rains in Mentougou district in Beijing on July 31, 2023. /CFP
Typhoon Doksuri, which hit the Chinese mainland last week, brought the worst torrential rain-triggered floods and landslides to parts of north and northeast China in 140 years. Fangshan and Mentougou, the two districts in Beijing that were struck the hardest by the latest devastating floods, are speeding up post-disaster recovery and guarding against secondary geological hazards.
In July 2021, floods devastated New York and Flagstaff, Arizona. In Germany and Belgium, floods swept away whole towns and left over 1,000 people missing. During June 2021, storm rain drenched Detroit, flooding streets and residences and overwhelming municipal drainage systems.
According to the United States Environmental Protection Agency, flooding is becoming more frequent along the U.S. coastline. Every site measured has experienced an increase in coastal flooding since the 1950s.
Frequency of Flooding Along U.S. Coasts, 2011–2020 Versus 1950–1959. /NOAA
According to the IPCC Sixth Assessment Report that global greenhouse gas emissions are increasing global average temperatures. Warming leads to increasing precipitation and more intense downpours, and this increases flood potential.
Anne Jefferson, a hydrologist at Kent State University, said that towns can construct or improve pipes, pumps, and rain gardens, but climate change is swiftly upending normal conditions and posing challenges to infrastructure that is meant to survive for decades.
According to Richard Rood's research, a professor in the Department of Climate and Space Sciences and Engineering at the University of Michigan, pavement is a key contributor to urban floods because water cannot be absorbed and flows off quickly. Similarly, water flows off the soil rather than soaking in after a forest fire or prolonged drought. This can overload drainage systems and cause debris to accumulate, clogging pipes and culverts.
A New Market Volunteer Fire Company rescue crew member wades through high waters following a flash flood, as Tropical Storm Henri makes landfall, in Helmetta, New Jersey, on August 22, 2021. /CFP
What can cities do to prepare for flooding? According to The Economist, planting trees and shrubs along streets can reduce run-off. One experiment in British Columbia discovered that urban trees can catch around half of the rainfall. Cities can also prevent water from going where it should not. To make room for water, playgrounds, sports facilities, and parks are being built in Rotterdam, the Netherlands' second-largest city. A basketball game can start on a sunny day in Benthemplein square. When the skies darken, though, the subterranean court serves as a rainwater basin.
Most of the worst issues are found below street level. Sewers frequently struggle to keep up and reintroduce their contents into buildings, streets, and rivers. In part to prevent this, London is constructing a new "super sewer" that will be finished by 2025. Greater Chicago has been constructing the "Deep Tunnel" since the mid-1970s. This tunnel is intended to drain storm water and sewage into holding reservoirs because Greater Chicago is essentially constructed on a swamp.
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