Aerial photo taken on April 21, 2022 shows a ranger patroling around Yoigilangleb Qu (river) in Qumalai County of Yushu Tibetan Autonomous Prefecture in northwest China's Qinghai Province. Yoigilangleb Qu (river) is located at the core area of Sanjiangyuan National Park. Sanjiangyuan, meaning the "source of three rivers," is home to the headwaters of the Yangtze, Yellow and Lancang rivers. (Photo: Xinhua)
Rangers patrol around Yoigilangleb Qu (river) in Qumalai County of Yushu Tibetan Autonomous Prefecture in northwest China's Qinghai Province, April 21, 2022. Yoigilangleb Qu (river) is located at the core area of Sanjiangyuan National Park. Sanjiangyuan, meaning the "source of three rivers," is home to the headwaters of the Yangtze, Yellow and Lancang rivers. (Photo: Xinhua)
Rangers patrol around Yoigilangleb Qu (river) in Qumalai County of Yushu Tibetan Autonomous Prefecture in northwest China's Qinghai Province, April 21, 2022. Yoigilangleb Qu (river) is located at the core area of Sanjiangyuan National Park. Sanjiangyuan, meaning the "source of three rivers," is home to the headwaters of the Yangtze, Yellow and Lancang rivers. (Photo: Xinhua)
A ranger patrols around Yoigilangleb Qu (river) in Qumalai County of Yushu Tibetan Autonomous Prefecture in northwest China's Qinghai Province, April 21, 2022. Yoigilangleb Qu (river) is located at the core area of Sanjiangyuan National Park. Sanjiangyuan, meaning the "source of three rivers," is home to the headwaters of the Yangtze, Yellow and Lancang rivers. (Photo: Xinhua)