A water puzzle水的困惑.docVIP

A water puzzle In North China’s Inner Mongolia region, scientists are investigating how there can be so much water in a desert. In the Badain Jaran Desert, more than 100 lakes can be found among huge sand dunes. Some of the dunes are more than half a kilometer high. How do the lakes survive in a hot desert and why do the dunes not move with the winds? A Chinese scientist has discovered a large reservoir of water underground and this may provide water to the lakes. This underground water also keeps the dunes in place. When sand is dry, it is blown by the wind; but if it is wet, it stays in one place. The Chinese team of scientists have found water 20 centimeters below the surface of the dunes. They know that the annual rainfall is 40 millimeters and that in this desert, 4,000 millimeters of water evaporates each year. So the extra water underground is not just from rain water. They believe that the underground water comes from melted snow in the mountains 500 kilometers to the southwest in the Qilian Mountains. They think that it takes between 30 and 40 years for the water to travel to the lakes and that there is 500 billion liters of water there. The farmers in the Badain Jaran area need water very badly for their crops and one plan is to divert a major river from the Qilian Mountains. The Chinese scientists believe it may be possible to send the underground water to the farmers by using underground tunnels. They have published their findings in the magazine Nature and other scientists have added their opinions. Some think that it will be too difficult to extract the underground water. Others do not believe that the water in the lakes comes from melted snow in the distant mountains. They think that underground water can only move a few meters each year. There are also fears that the scheme will damage the ecology of the area. So, the discussion and research continues until a good solution is found.