Experts, backed by recent studies, are warning that unplanned underground water exploitation and improper zoning plans are causing Hanoi to sink, local news website Dat Viet reported Thursday.
A recent study by the Hanoi Institute of Construction Science, Technology and Economics under the city's Department of Construction, showed that Hanoi is subsiding every year, by 22.16 mm in Phap Van urban area to 41.42 mm in Thanh Cong Ward, according to the news source.
It also quoted another study by the Association of Hydrogeology and Construction Geology as saying that the Linh Dam and Thanh Cong areas are at very high risk of subsiding because of excessive construction and underground water projects.
Weak soil, in fact, is distributed across Hanoi, putting some places at risks of sinking, Do Minh Toan, former dean of Hanoi University of Mining and Geology's Geology Department, told the news website.
The deeper underground water projects are conducted, the higher the risk of collapsing constructions, he warned.
He said new urban areas with many multi-story buildings have been planned in areas with very high sinkage risks like Ngoc Khanh, Giang Vo and My Dinh.
The subsidence also affects the accuracy of figures on the maximum possible height of a construction project, he stressed.
Agreeing with Toan, engineer Le Tu Hai said weak soil was causing easily recognizable impacts like cracks and subsidence at constructions with weak foundations.
On the other hand, it implies effects that can't be realized in a short time like the risks of distortion and collapse of constructions, the engineer told Dat Viet without saying how many years of life the constructions can have.