Mountains in China are being bulldozed to make way for cities, but environmentalists are warning this could prove to be a disaster. Mountaintops are being flattened, and valleys filled in to prepare areas for building. 

Environmentals at one university in China are calling the actions unsustainable, saying it will lead to flooding, erosion and pollution. 

Over the last decade, dozens of mountains have been destroyed and valleys have been filled in as part of the drive. Little study has been conducted on how this large-scale redistribution of geology will affect the environment. 

Chang'an University researchers believe the consequences of these actions could prove disastrous. They believe the process cold destroy farmland, and habitats for native species, in addition to other environmental dangers presented by the earth-moving. 

Around 20 percent of the population of China lives in mountainous regions, and cities are rapidly expanding as the Chinese economy grows. 

Similar shaving of mountains, and filling of valleys has taken place in America, but not on the unprecedented scale currently taking place in the world's most-populous country. 

The Foolish Old Man who Removed the Mountains is an ancient tale in China. The story tells of a 90-year-old man who tells his neighbors he can remove two mountains that block the path to his help. In the story, the elderly man succeeds, with the help of deities. Chinese revolutionary Mao Zedong used the allegory as an example of the power of perseverance. Today, the group believes this tale should be a warning of such actions with the support of scientists and environmentalists. 

In Yan'an, in Shaanxi Province, one project alone is aimed at flattening over 30 square miles of land for new construction. That project started in April 2012, and is taking place on loess, wind-blown silt, which sat for a million years. Investigators believe redistributing this material could could the ground to collapse after a rainstorm. 

"There has been too little modeling of the costs and benefits of land creation. Inexperience and technical problems delay projects and add costs, and the environmental impacts are not being thoroughly considered," researchers wrote.  

The air in Yan'an is filled with dust and pollution from the near-constant construction. This could prove a health hazard to many in the area, including children and the elderly. 

Proponents of wide-scale modification of the region say economic benefits will more than cover damages. However, no construction can take place on such filled in areas for a decade, as the ground needs time to settle. 

Commentary on the practice of flattening mountains and valleys in China, and the environmental consequences it could have, was published in the journal Nature.