China's effort to make more room for cities by "shaving" the tops off mountains and filling in adjacent valleys could come at the cost of flooding, erosion and pollution, researchers in the country are saying.
In an unprecedented redistribution of tons of earth over the last decade, dozens of mountain peaks as tall as 490 feet have been made flat, with the earth used to fill up adjacent valleys and create many square miles of land for development.
Researchers from Chang'an University have expressed concern about the lack of environmental impact studies or cost assessments accompanying the projects.
"Land creation by cutting off hilltops and moving massive quantities of dirt is like performing major surgery on Earth's crust," they wrote in a commentary in the journal Nature.
While removing entire mountaintops has been performed in strip mining operations in the United States, the scale of the program underway in China dwarfs that, they wrote.
China's program, meant to move rural residents to new city to spur the county's economic growth, was first put into operation to expand the city of Shiyan in the country's central Hubei province in 2007.
The commentary authors said the result was flooding, landslides and increased amounts of sediment in area water sources.
Li Peihue, one of the commentary's authors, acknowledged that developing cities would always carry 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.
In another project in the Shannxi provine, the city of Yan'an intends to almost double its available area by modifying mountains and valleys to create 30.5 square miles of flat ground.
The local earth is a type of windblown silt called loess, and valleys filled with it may be unstable and ripe for "geological disasters such as landslides," Li said.
The Yan'an effort would cost $16 billion and take 10 years, but it will be at least that long before the filled-in valleys settle and become sufficiently stable for new development, he said.
Around a fifth of China's population lives in the country's mountainous regions, where narrow valleys a population density limit room for development of cities.
"China is moving mountains. Until we know more about the consequences, we urge governments to seek scientific advice and proceed with caution," the commentary's authors wrote.
