People pave straw checkerboard sand barriers to prevent and control desertification in Changliushui desert area of Zhongwei City, northwest China's Ningxia Hui Autonomous Region, June 13, 2019. Located on the southern edge of the Tengger Desert, Zhongwei City has been curbing desertification by making straw checkerboard sand barriers and sowing with grass seeds. Some 1,470,000 mu (about 98,000 hectares) of desert has been processed in Zhongwei by the end of 2018. (Xinhua/Feng Kaihua)