Chinese earth-movers shave off mountaintops in Lanzhou, Gansu province, to make way for cities.

Chinese earth-movers shave off mountaintops in Lanzhou, Gansu province, to make way for cities.

For years, China has been moving mountains for its people - literally.

The country has been bulldozing hundreds of mountains to make way for new cities but scientists are not happy, saying the consequences of the policy ''have not been thought through''.

In the past decade, mountains stretching over hundreds of kilometres have been demolished and the soil shovelled into valleys to create flat land, in a practise that has become commonplace in China.

Scientists have criticised the campaign to flatten mountains to make way for cities.

Scientists have criticised the campaign to flatten mountains to make way for cities.

The city of Lanzhou, in Gansu province, is in the process of bulldozing more than 700 mountains in what's been dubbed the largest ''mountain-moving project'' in Chinese history.

One of China's biggest construction firms is behind the multibillion-dollar plan, which will create more than 250 square kilometres of flat land and allow developers to build a brand new city.

The practise has spawned more land for Chongqing, Shiyan, Yichang, Lanzhou and Yan'an cities. One of the largest projects, in Yan'an in the Shaanxi province, is set to double the city's area by creating 78.5 square kilometres of flat terrain.

One-fifth of China's population is estimated to live in mountainous areas and while cities are expanding rapidly, land available for development is in short supply. Local officials think that razing the mountains and selling or leasing the new land will generate billions of yuan and ease pressure on agriculturally or culturally valuable land elsewhere.

While creating land by slicing the tops off mountains has been done before in strip mining, especially in eastern United States, it has never been carried out on a scale as large as that in China and the consequent infill has never been used before for urban construction.

But now, years after the mountain-flattening projects started, three Chinese academics have condemned the campaign, writing in the journal Nature that ''earth-moving on this scale without scientific support is folly''.

''There has been too little modelling of the costs and benefits of land creation. Inexperience and technical problems delay projects and add costs, and the environment impacts are not being thoroughly considered,'' Chang'an University researchers Peiyue Li, Hui Qian and Jianhua Wu wrote.

The authors state that local governments in China are prioritising money over the environment.

They write that when air pollution caused by the Lanzhou project became visible in April 2013, work was halted pending an environmental assessment. But it was resumed four weeks later because costs to the local government and contractors were mounting. The assessment still hasn't been completed.

''Land-creation projects are already causing air and water pollution, soil erosion and geological hazards such as subsidence. They destroy forests and farmlands and endanger wild animals and plants."

During the massive earth-moving project in the city of Lanzhou, soil erosion is predicted to increase by 10 per cent and concentrations of dust particles in the air by 49 per cent. In Yan'an, the air is often brown with dust owing to construction teams working on windy days without thinking to dampen the soil first.

The trio says research into the land creation is ''local and narrow'' with funds granted to research teams with ''limited experiences and skills''.

''Until we know more about the consequences, we urge governments to seek scientific advice and proceed with caution."