Photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Jiang Wenyao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Jiang Wenyao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Hu Chao)

Aerial photo taken on Dec. 9, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Hu Chao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Hu Chao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Hu Chao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Hu Chao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Jiang Wenyao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Hu Chao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Jiang Wenyao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Hu Chao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Hu Chao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Hu Chao)

Aerial photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Hu Chao)

Photo taken on Dec. 10, 2021 shows the scenery of a wetland in Panlong District in Kunming, southwest China's Yunnan Province. The wetland is located at Songhuaba water source reserve, also the upper reaches of the Dianchi Lake. (Xinhua/Jiang Wenyao)