Aerial photo taken on Sept. 15, 2020 shows the scenery of Gahai Lake in Luqu County of Tibetan Autonomous Prefecture of Gannan, northwest China's Gansu Province. The area of Gahai Lake has been expanding in recent years due to plentiful rainfall and the improving ecological environment. (Xinhua/Zhang Zhimin)

Aerial photo taken on Sept. 15, 2020 shows the scenery of Gahai Lake in Luqu County of Tibetan Autonomous Prefecture of Gannan, northwest China's Gansu Province. The area of Gahai Lake has been expanding in recent years due to plentiful rainfall and the improving ecological environment. (Xinhua/Zhang Zhimin)

Aerial photo taken on Sept. 15, 2020 shows the scenery of Gahai Lake in Luqu County of Tibetan Autonomous Prefecture of Gannan, northwest China's Gansu Province. The area of Gahai Lake has been expanding in recent years due to plentiful rainfall and the improving ecological environment. (Xinhua/Zhang Zhimin)

Aerial photo taken on Sept. 15, 2020 shows the scenery of Gahai Lake in Luqu County of Tibetan Autonomous Prefecture of Gannan, northwest China's Gansu Province. The area of Gahai Lake has been expanding in recent years due to plentiful rainfall and the improving ecological environment. (Xinhua/Zhang Zhimin)