Typhoon Doksuri, the most powerful storm in China this year, churned north in late July after making landfall in the south, bringing exceptional rainfall to the Hai river basin, a region that typhoons rarely hit, and precipitation that the Chinese capital has not seen since records began 140 year ago.Five rivers flow into the Hai river basin, the largest natural drainage system in northern China. The basin includes Beijing, Hebei province and the big port city of Tianjin.
Rapid urbanisation has meant the spread of impermeable concrete surfaces and reduced natural wetlands and marshes that had in the past absorbed rain.flood storage areasChina's Soviet-era urban drainage systems of shallow buried pipes leaves cities vulnerable to waterlogging during heavy rain, in contrast with cavernous underground storm "corridors" in cities such as Tokyo.
On July 31, Hebei officials opened floodgates in seven low-lying flood storage areas, including two in Zhuozhou, in what officials said was an "inevitable" decision to prevent rivers bursting their banks and to protect cities downstream.