Photo taken on Sept. 12, 2018 shows fixed sand dunes near the source of the Yarlung Zangbo River in Zhongba County of Xigaze, southwest China's Tibet Autonomous Region. A series of protection measures against desertification at the source of the Tibetan region's mother river, the Yarlung Zangbo River, were taken by the local government in recent years. The environment there has been greatly improved after years of efforts. (Xinhua/Purbu Zhaxi)