Aerial photo taken on Aug. 11, 2020 shows the Yulonghe Park in Anci District of Langfang City, north China's Hebei Province. In recent years, local authorities in Langfang's Anci District have launched a series of projects to improve the ecological environment and water quality for residents. (Xinhua/Wang Xiao)

Aerial photo taken on Aug. 11, 2020 shows the Longhe River artificial wetland park in Anci District of Langfang City, north China's Hebei Province. (Xinhua/Wang Xiao)

A staff member operates equipment for sludge dehydration at a management center in the Longhe River artificial wetland park in Anci District of Langfang City, north China's Hebei Province, Aug. 11, 2020. (Xinhua/Wang Xiao)

Athletes take a training session in the Longhe River in Anci District of Langfang City, north China's Hebei Province, Aug. 11, 2020. (Xinhua/Wang Xiao)