Aerial photo taken on Aug 9, 2019 shows the view of Qumar River at the headstream region of Yangtze River, China's longest river, in Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. (Xinhua/Wu Gang)

Aerial photo taken on Aug 9, 2019 shows the view of Qumar River at the headstream region of Yangtze River, China's longest river, in Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. (Xinhua/Wu Gang)

Aerial photo taken on Aug 9, 2019 shows the view of Qumar River at the headstream region of Yangtze River, China's longest river, in Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. (Xinhua/Wu Gang)

Aerial photo taken on Aug 9, 2019 shows the view of Qumar River at the headstream region of Yangtze River, China's longest river, in Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. (Xinhua/Wu Gang)

Aerial photo taken on Aug 9, 2019 shows the view of Qumar River at the headstream region of Yangtze River, China's longest river, in Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. (Xinhua/Wu Gang)

Aerial photo taken on Aug 9, 2019 shows the view of Qumar River at the headstream region of Yangtze River, China's longest river, in Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. (Xinhua/Wu Gang)

Aerial photo taken on Aug 9, 2019 shows the view of Qumar River at the headstream region of Yangtze River, China's longest river, in Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. (Xinhua/Wu Gang)

Aerial photo taken on Aug 9, 2019 shows the view of Qumar River at the headstream region of Yangtze River, China's longest river, in Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. (Xinhua/Wu Gang)

Aerial photo taken on Aug 9, 2019 shows the view of Qumar River at the headstream region of Yangtze River, China's longest river, in Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. (Xinhua/Wu Gang)

Aerial photo taken on Aug 9, 2019 shows the view of Qumar River at the headstream region of Yangtze River, China's longest river, in Yushu Tibetan Autonomous Prefecture, northwest China's Qinghai Province. (Xinhua/Wu Gang)