Tag Archives: rain

Storing Beijing’s Storm Water Before It Does Harm

Firefighters pull a submerged car near Guangqumen Bridge in Beijing, July 21, 2012.  (Xinhua/Li Fangyu)

Following the heavy rains that recently inundated Beijing with such loss of life, the capital is to build 20 underground flood pools to relieve future storm flooding. They will be put under places known to susceptible to flash floods, low-lying roadways in particular.

A conventional surface flood pool is the land around a reservoir that is intended to be flooded in the event of extreme rains as the reservoir rises and backs up. The excess water is then run off by being released through the reservoir’s dam in subsequent days. Underground storm water storage works in much the same way, temporarily holding storm water until a city’s drainage system can handle it.

Flood pools are not only a common form of flood management, but, smartly managed, are also a potentially profitable source of municipal water supplies, irrigation, recreation facilities and fish or wildlife habitats, Beijing’s flood pools won’t bring such broad public goods as far as we can tell. They will have to be fitted in between all the other subterranean construction beneath a long-established city: sewer and water pipes, subway lines, building foundations and the like.

Modern underground storm water storage systems are often modular, so can be constructed as shape and space allows. Alternatively they can be built from large diameter pipes and threaded around obstructions. Their capacity is typically equivalent to a swimming pool and are easiest to retrofit to places like roads and parking lots that can be dug up and the systems installed under them.

Urban flooding is a worsening problem in China (and elsewhere) as global warming, urbanization and industrialization pose a growing triple threat to cities’ natural defences, defenses urban planners have anyway been concreting over with reckless abandon.  It is, though, reasonable to ask why there hasn’t previously been more provision to deal with flash floods in the capital.

Hong Kong, for one, has underground storm water storage in several of its towns already and is planning to build more, notably in Happy Valley on Hong Kong Island which is to get an award winning, state of the art flood pool at a cost of HK$1 billion ($130 million). Hong Kong had the advantage of being able to build the lower -tech tanks it already has into its new towns from the outset, a luxury that Beijing doesn’t enjoy.

Urban planners are only now realizing that they have to make cities greener so they are less encouraging to extreme weather. All the newly constructed impervious surfaces such as roads, parking lots and rooftops, create run-offs that existing urban drainage, often old and inadequate, can’t handle. can’t handle.  Not only is ground storage for rainwater scarce and run-offs from hard surfaces absent, ancient streams that could carry rainwater to rivers and ponds that could help it find its way to acquirers below have been filled in. As Beijing’s are expensively learning– the economic cost of the recent floods  is estimated to be at least 2.3 billion yuan ($360 million), before the cost of installing the new storage tanks–they need to create the modern urban equivalent of something nature has provided naturally.

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Death Toll In Central China Flooding Nears 60

While drought persists in the southwest, heavy rains are proving deadly in Henan, Shaanxi and Sichuan. Officials at the Ministry of Civil Affairs say that 57 people have been killed and a further 29 are missing as a result of torrential rain-triggered flooding and landslides in the three provinces since the beginning of the month. More than 12 million people have been affected, with more than 1.2 million having to be evacuated. In recent days the rains have raised the levels of the Han, Wei and Jialingjiang rivers, leading to floods in 14 rivers and tributaries of the Yangtze and Yellow rivers. Water levels at the Three Gorges Reservoir swelled to above 160 meters on the evening of Sept. 19, 16 meters higher than the alert level. Emergency relief teams have been sent to all three provinces where direct economic losses are put at upwards of 17 billion yuan ($2.7 billion) so far.

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More Rains Lash China, Death Toll Mounts

More torrential rains are lashing Gansu and southwestern Sichuan, triggering deadly mud- and landslides that have left a further 49 dead and 82 missing across the two provinces. These follow the Aug. 8 disaster in Zhouqu where the death toll is now put at 1,254 with 490 still unaccounted for.

Communications, water and power supplies are being restored in the town as a massive relief effort continues to get supplies to the remote town and other affected areas. One piece of cheer from Zhouqu is that public health officials say they have had no reports of outbreaks of infectious disease so far.

In all. the rains are being blamed for the deaths of more than 2,300 people across the country so far this year with a further 1,200 missing. And. as we have written too often this year, more rain is in the forecast.

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Deadly Rains Continue To Wreak Havoc

The monsoon rains that have inundated several central and southern provinces this month have brought the most severe flooding that Fujian, Jiangxi, Hunan and Guizhou have suffered in half a century. Official figures put the death toll in June at at least 235 with a further 119 unaccounted for. At least 379 people have died as a result of flooding so far this year, the deadliest toll since 1998 when 3,600 died as a result of the rains.

On Monday, at least 107 people were buried by a rain-triggered landslide in Guizhou. In all more than 29 million people have been affected, with one in 10 those having to be evacuated from their homes. The economic cost is put at upwards of 82 billion yuan ($12 billion). Emergency relief efforts and fortification of riverbanks continues, as does the torrential rain with more in the forecast.

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