Undated photo shows the eye-catching scenery of Emerald Lake in Da Qaidam (also known as Dachaidan) district in Haixi Mongolian and Tibetan Autonomous Prefecture, northwest China's Qinghai Province. [Photo by Chen Falin/China News Service]

Undated photo shows the eye-catching scenery of Emerald Lake in Da Qaidam (also known as Dachaidan) district in Haixi Mongolian and Tibetan Autonomous Prefecture, northwest China's Qinghai Province. [Photo by Chen Falin/China News Service]

Undated photo shows the eye-catching scenery of Emerald Lake in Da Qaidam (also known as Dachaidan) district in Haixi Mongolian and Tibetan Autonomous Prefecture, northwest China's Qinghai Province. [Photo by Chen Falin/China News Service]