On July 21st, the heaviest rainstorm to strike Beijing, China in over 60 years dumped an average of more than 7 inches of rain across the city, causing floods and leading to the deaths of more than 70 people. One suburb, Fangshan, received more than 18 inches of rain from the storm.
The storm triggered devastating mudslides and have left thousands displaced or homeless.
According to Wu Zhenghua, a researcher at the Beijing Meteorological Bureau, rainstorms like this one will become more and more common in the future, thanks to a warming planet:
“Global warming has increased the temperature in the middle and high latitudes of the Northern Hemisphere, resulting in more water-vapor exchange and heat exchange with low-latitude regions, and thus bringing more frequent heavy precipitation.”
Storms like the recent Beijing event, though less severe, are not uncommon in southern regions. But they rarely ever venture as far north as Beijing. However, Wu claimed, there is statistical evidence that shows major storms have become more frequent in the north since 2008.
China is facing the same trends seen in the United States. A recent report from the Environment America Research and Policy Center entitled “When It Rains, It Pours,” looked at the increased severity and frequency of major precipitation events. The study found that extreme storms are occurring 30 percent more frequently in the U.S. than they were in 1948 and that major downpours are producing 10 percent more rain each year.
More intense rainstorms could be a major issue for China, which has problems with urban drainage systems. In China, storm drains are organized by location, with the most important sites and most traveled roads prioritized, thereby opening the possibility of flooding elsewhere. The drains were also built to handle one-in-five year storms; however, as the data suggests, storms of that magnitude may soon become the new normal.
The rain in the most recent storm fell at a staggering rate, almost five inches an hour in Beijing, about four and a half inches an hour in Hong Kong, and a little over four inches an hour in a province in central China — overwhelming the out-of-date and poorly-designed drainage and sewer systems that are capable of handling water levels less than a third of what was experienced.
According to Fang Chuanglin, an urban planner with the Chinese Academy of Science’s Institute of Geographic Sciences and Natural Resources Research:
“The problems with the drainage systems include improper arrangement of pipelines and outdated design. Most pipes are designed for the worst rainstorm in three or five years, some can only cope with the heaviest rain once a year,”
Over the last two years, Shanghai, Wuhan and Guangzhou have “announced multibillion-yuan projects to maintain and upgrade drainage systems,” but more must be done. As storms continue to become more intense and more frequent, floods will continue to be a major for infrastructure in China’s metropolitan centers.
– Max Frankel