BEIJING – China's campaign to shave off mountaintops and fill in valleys to make way for cities may come at too high a price in the pollution, erosion and flooding unleashed by the unprecedented redistribution of earth, Chinese researchers warned Thursday.
Dozens of peaks up to 150 meters (490 feet) tall have been flattened to fill up valleys and create tens of square kilometers of land over the past decade. But there has been little assessment of the costs and environmental impact of these projects, researchers at Chang'an University said in a commentary published in the journal Nature.
"Land creation by cutting off hilltops and moving massive quantities of dirt is like performing major surgery on Earth's crust," the group said.
In addition to causing air and water pollution, erosion, landslides and flooding, the projects have destroyed farmlands and habitat for wild animals and plants, the group said.
While mountaintop removal has been done before in mining in the United States, it has never been carried out on the scale underway in China or used to construct urban areas, the researchers said.
One of the authors, Li Peiyue, assistant professor of hydrogeology and environmental science, said in an interview that the development of cities must come at a price. "But we believe the government should be cautious in promoting the projects before proper experiments have shown that they are technological, geological and environmentally feasible," he said.
China's government is in a multi-year drive to move more rural residents to urban areas to develop into a more modern economy.
The first city to expand by bulldozing its mountaintops was Shiyan in central Hubei province in 2007. The transformation caused landslides and flooding, altered watercourses and increased the sediment content in local water sources, the commentary said.
In neighboring Shaanxi province, Yan'an city aims to double its area by creating 79 square kilometers (30.5 square miles) of flat ground in a project started in 2012 — in the largest such project attempted on loess, a kind of wind-blown silt. The project has destroyed farmlands while filling valleys with a kind of earth that may lack firmness and be vulnerable to "geological disasters such as landslides," Li said.
The authors questioned the cost benefits of landfills, noting that the Yan'an project will cost 100 billion yuan ($16 billion) over 10 years, but that it will take at least that long for the filled-in valleys to become stable enough for building.
Jennifer Turner, director of the China Environment Forum at the Washington, D.C.-based Wilson Center think tank, said the mountain-moving projects could leave China with more deserts and water shortages, as well as other unforeseen costs.
"There are these uncoordinated massive engineering projects," Turner said. "And I wonder as well ... if anyone's done any analysis, not only on the water footprint but the energy footprint of actually constructing cities in this way, because cities need cement, they need steel."
Associated Press researcher Yu Bing contributed to this report.