Aerial photo taken on Aug. 14, 2020 shows a wholesale market flooded by the Yangtze River at Caiyuanba, southwest China's Chongqing Municipality. Yangtze River, China's longest, has recorded the fourth flood of the year in its upper reaches after a spell of heavy rainfall, authorities said Friday. (Xinhua/Huang Wei)

WUHAN, Aug. 14 (Xinhua) -- Yangtze River, China's longest, has recorded the fourth flood of the year in its upper reaches after a spell of heavy rainfall, authorities said Friday.

The flood was triggered by rising water levels in the river's tributaries along the upper reaches, leading to a rapid increase of flow into the Three Gorges reservoir.

At 5 a.m. Friday, the reservoir saw an inflow of 50,900 cubic meters per second, which is expected to reach around 59,000 cubic meters per second early Saturday, according to the Changjiang Water Resources Commission of the Ministry of Water Resources.

The commission called on the provinces and cities along the Yangtze River to spare no efforts in preparing for the flood.

Aerial photo taken on Aug. 14, 2020 shows water gushing out from the Three Gorges Dam in central China's Hubei Province. Yangtze River, China's longest, has recorded the fourth flood of the year in its upper reaches after a spell of heavy rainfall, authorities said Friday. The flood was triggered by rising water levels in the river's tributaries along the upper reaches, leading to a rapid increase of flow into the Three Gorges reservoir. (Photo by Zheng Jiayu/Xinhua)

Photo taken on Aug. 14, 2020 shows water gushing out from the Three Gorges Dam in central China's Hubei Province. Yangtze River, China's longest, has recorded the fourth flood of the year in its upper reaches after a spell of heavy rainfall, authorities said Friday. The flood was triggered by rising water levels in the river's tributaries along the upper reaches, leading to a rapid increase of flow into the Three Gorges reservoir. (Photo by Zheng Jiayu/Xinhua)

Photo taken on Aug. 14, 2020 shows water gushing out from the Three Gorges Dam in central China's Hubei Province. Yangtze River, China's longest, has recorded the fourth flood of the year in its upper reaches after a spell of heavy rainfall, authorities said Friday. The flood was triggered by rising water levels in the river's tributaries along the upper reaches, leading to a rapid increase of flow into the Three Gorges reservoir. (Photo by Zheng Jiayu/Xinhua)