The Mysterious Lakes of Badain Jaran Desert
... "The Badain Jaran Desert occupies parts of China and Inner Mongolia covering an area of 49,000 sq. kilometers making it the third largest desert in China. Although not a lot of people are familiar with this desert, outside China, it is known for having the tallest stationary dunes on earth. Some of these dunes have been measured to reach heights of more than 500 meters. Badain Jaran has an extremely arid climate with an annual precipitation between 50-60mm. Nearly 40-80 times of the precipitation gets evaporated away before it falls as rainfall.
Despite these dry conditions, one of the most remarkable feature of Badain Jaran is the existence of nearly 140 permanent lakes that lie between the dunes. It’s these lakes that give the desert its name which in Mongolian means "mysterious lakes".
These mysterious lakes are believed to be fed by underground water springs that flow under the gravel deposits and appear between the dunes where the deposits become fine-grained and the water flow is blocked. The source of this water is precipitation and snowmelt in the mountains surrounding the desert hundreds of kilometers away. Runoff from these mountains flows through the fractured rocks and through gravel deposits beneath the desert, and emerge at scattered places giving rise to numerous lakes. Although the springs carry fresh water, most of the lakes are saline, which can be explained by their high rate of evaporation. Some of the lakes change color due to the presence of a large populations of algae, brine shrimp and minerals. Evaporation have also led some hypersaline lakes to form salt crust around the rim of the lakes.
The fresh water lakes provide the life sustenance in the desert supporting camels, goats and horses which are herded by nomads that travel through the desert. Most lakes also support a green ring of vegetation that populate the close vicinity around the lakes.
In recent decades, some of these lakes have shrunk or even disappeared, as a result of reduction in groundwater brought about by urbanization, irrigation, water diversion, and an increase in population. ..."