NANNING, Aug. 11 (Xinhua) -- Poor management of underground space is causing a number of subsidence cases in China's urban cities.
In Nanning, capital of south China's Guangxi Zhuang Autonomous Region, three cases of sinking land have been reported since the beginning of August. The city reported 25 subsidence cases from May to July, according to official statistics.
Elsewhere, four people were trapped in a hole after land near a convenience store suddenly sank in Shenzhen City in southern Guangdong Province last week.
At a national seminar on the dangers and causes of collapsing roads and pavements last month, experts pointed out that urban cities like Beijing, Shanghai, Guangzhou and Harbin suffer from land subsiding. Harbin reported seven cases within eight days in August 2012, which left two people dead and two injured.
Government statistics showed that more than 50 cities in 20 provinces and regions in the country have reported subsidence cases.
Subsidence, which mostly occur at major road conjunctions, can cause damage to a city's transport network and adds to the concerns of city residents.
"Land sinking is highly unpredictable and could cause casualties," said Hu Chunlong, senior engineer with Guangxi's regional institute of geological and prospecting engineering.
As subsidence occurs more often, worried residents use the term "zoulusi," or "death while walking" in English, to vent irony and anger.
Some government officials have blamed abnormal weather as well as geological changes for the holes, but experts said the causes are due to mismanagement of underground development amidst fast urbanization.
Luo Guoan, a researcher with the sociology department of Guangxi Academy of Social Sciences, said giant city projects such as the construction of subways involves fast-paced underground development, but management fails to keep up.
He said current development is not very well organized, and many projects are carried out in a disorderly manner, creating lots of "road black holes."
"For example, if several underground pipelines need to be updated, it is hard to coordinate the working staff because they are 'only committed to their designated work'," Luo added.
He said many old underground pipelines are not updated in time due to mismanagement, and that has resulted in water leakages, which softens the ground and leads to subsidence.
He said substandard work is also to blame, saying that many workers fail to check if there is soft soil after construction, which causes the potential for subsidence.
Hu Chunlong emphasized the importance of inspecting projects on a regular basis and enhancing precautionary measures as well as emergency responses in case of subsidence.
He said that a more comprehensive management mechanism should be in place to organize underground development so that safety is high on the agenda during China's urbanization process.