A swollen subtributary of the Yangtze River has sent a deluge to Danjiangkou Reservoir, a major reservoir in central China's Henan and Hubei provinces, the state flood control agency said Sunday.

The water level of the Danjiang River, a tributary of the Hanjiang River, rose to 217.59 meters Saturday afternoon, with a water flow of 10,000 cubic meters per second, the highest since 1953, said a statement of the State Flood Control and Drought Relief Headquarters.

Hanjiang River is the second largest tributary of the Yangtze River, China's biggest river.

Flood gushed into the Danjiangkou Reservoir, at the confluence of the Danjiang and Hanjiang rivers, 34,100 cubic meters a second early Sunday, the second biggest deluge since the reservoir was built in 1968.

Liu Ning, vice minister of water resources and secretary general of the State Flood Control and Drought Relief Headquarters, said Sunday that local authority should closely monitor the weather, and step up monitoring efforts against potential flood risks.

Premier Wen Jiabao has ordered local governments to adopt scientific measures to prepare well for "more serious floods and disasters" as some of the country's major rivers surpassed their warning levels.

Wen said China was at a "crucial stage" for flood control during an inspection tour in Hubei Province that began July 23.