There is a very nice site: Kuriositas.com with beautiful photo's and a good story.
Below is just an impression, a teaser but don't forget to go to the original!
For thousands of years pilgrims and traders on the Silk Road to the West have used the Crescent Lake oasis as a last stop off before they face the hardships of the Gobi Desert. Six kilometers from the city of Dunhuang the oasis has persevered throughout the millennia. However, it may now be reaching its Waterloo.
As well as an exit to the West, Dunhuang was for more than two thousand years a crucial entrance in to China. Travelers followed a string of oases, skirting around the unforgiving sands of the Gobi and Taklamakan Desert. In this fashion they would also avoid the ghosts and demons that were said to haunt the desert. It was said that the desert was so desolate and devoid of life that the bones of those who had died in it were used as signposts.
Imagine the pleasure, then, of the travelers as they reached Crescent Lake. Locals say that it takes the shape of the eye of a beautiful woman, lucid, clear and seductive. Yet the very existence of the beautiful desert oasis of Crescent Lake is threatened.
Over the last thirty years the water has dropped at least twenty five feet. This is as a result of two things – the local farmers have redirected the water to feed their crops. Secondly the population of Dunhuang has more than doubled in that period. A desperate attempt to feed the lake from an artificial aqueduct failed (due to pollutants) and so each year the lake slowly shrinks a little more.
A fragile desert hydrology, stable for thousands of years is now overstressed and the wonderful place that is Crescent Lake is feeling the strain. This ecological crisis is due purely to human impact – much more water than the area can sustain is being used. However, there may be a human solution to this manmade disaster.
The issue has been compounded by the fact that western China is the country’s poorest region and the drive towards economic development at all costs left the local people with little choice. There is no industry as such in Dunhuang – what manufacturer would set up in the middle of a desert after all? What that meant was that the local industry already in place was forced to expand – and that industry is agriculture.
The Dang River which flowed past the city and was what inspired the original settlers to live there has been dammed. That was a few decades ago and certainly, the yield of the local farms improved. However with that improvement came the inevitable human arrivals to assist with further expansion. More people meant more demand for water and so the underground water table inevitably began to drop.
In a desperate attempt to stave off disaster local officials have brought in a new, strict policy. It is known as the Three Forbids. No new wells are allowed, no additional farmland may be irrigated and new migrants are prohibited. The first two forbids rather than the last are the most punitive to locals as more than ninety percent of the water goes to agriculture.
The key to retaining the oasis will be in the reduction of water consumption. Despite the tourism that the Crescent Lake attracts the amount of glacial melt from the distant Qilian Mountains that feeds the Dang River has not changed for many centuries. If the Three Forbids is rigorously enforced then perhaps the Crescent Lake will be enjoyed by many generations to come.