Abstract: The surface water is very important to local economic development and ecological protection in Mu Us Sandy Land among Inner Mongolia,Ningxia and Shaanxi Province,China. The spatial-temporal changes of surface water in the middle areas of Mu Us Sandy Land were analyzed by using Landsat TM/ETM+ images of 1999,2006,2013,2015. The surface water shrunk about 125.71 km²(35.2%)from 1999(368.51 km²)to 2006 (242.81 km²),and then recovered in 2013(299.59 km²)and 2015(299.82 km²). The area of water body in 2015 was still about 18.64% less than that in 1999,the long-term change trends of annual precipitation and yearly average air temperature are not significant(at ɑ =0.05). The water consumption with effective irrigation area,livestock, raw coal production from 1999 to 2014 suggest that water body decrease mainly caused by increased coal mining(2 252.2%)in north part while by increased agricultural irrigation(92.4%)and grazing(24 614.7%)in South part. We found that Chagan Lake is nearly stable with small fluctuation under the increased coal mining and the strictest water protect policy,while the area of natural water body of Yiheri Lake has continued to decline by 1 km²(29.9%)over the past 16 years. These results indicate that the water protection measures are very important to maintain the stability of the lakes.

Key words: Mu Us Sandy Land, surface water changes, remote sensing, human activity, regulate and control