20 percent more rainfall is possible in river's middle reaches; El Nino also could play a role
The chances of heavy flooding have increased on the middle and lower reaches of the Yangtze River, officials warned on Tuesday. [Special coverage]
They said river basin areas could be hit by more downpours and extreme weather conditions than in previous years.
Middle reaches of Yangtze basin areas could receive 20 percent more rainfall than before, according to the hydro-graphic office of the Changjiang Water Resources Commission.
The commission operates under the Ministry of Water Resources.
Extreme weather conditions, including strong winds and downpours, have been blamed for the capsizing of a Yangtze cruise ship with 456 people on board on Monday evening.
The vessel overturned on a section of the river near Jianli county, Hubei province, which lies on the middle reaches of the Yangtze.
Jianli county and nearby areas were hit by torrential downpours on Monday night, with the county reporting precipitation of 158.8 mm within nine hours. Moderate to strong rainfall was forecast for the county on Tuesday night, the China Meteorological Administration said in a statement.
The downpours increased water levels on the middle reaches of the Yangtze River, with the water resources commission reducing water discharged from the Three Gorges Dam to aid the rescue and recovery effort.
Wei Shanzhong, secretary-general of the water commission, said the risk of flooding was also rising.
Since the river basin areas received less rainfall in April and early May, the chances increased that precipitation will be concentrated in June, July and August, the major flooding season on the Yangtze, he said.
Cheng Haiyun, deputy head of the hydrographic office under the commission, said, "Strong rainfall started in the middle of May, and we are expecting more in the coming months in the Yangtze River area, especially the middle and lower reaches."
Cheng said officials are still unable to predict when the river will flood, as there are several factors to be considered.
El Nino - a warming of sea surface temperatures in the Pacific that affects wind patterns - could also play a major role in the coming months, according to the meteorological administration.
In 1998, El Nino caused the country's worst flooding on the Yangtze in half a century, killing thousands of people.
The strong rainfall this year has already resulted in flooding on a number of Yangtze tributaries, including the Ganjiang River in Jiangxi province and the Xiangjiang River in Hunan province.