A team of the Army's Military Engineering Group is set to arrive at Kozhikode and Ernakulam, officials said, adding that some Army officers from Kannur had already reached the flooded Wayanad.

The worst affected districts include Idukki, Malappuram, Palghat, Kozhikode, Wayanad and parts of Kannur.

Following the opening of the Idamalayar dam gates, the flood water from the Periyar river entered the Cochin International Airport compound, forcing the authorities to temporarily shut operations in the afternoon. The airport reopened after the water receded at 3 p.m.

A Home Ministry statement said 22 persons died in overnight rains and landslides on August 8-9. Idukki alone accounted for 11 deaths.

Two Class 12 students who ventured out for fishing in the flooded waters near Kochi were also swept away. Their bodies were found, officials said.

Four teams of the National Disaster Response Force have left Chennai for Kerala. An inter-ministerial Central team is visiting the flood-ravaged area and Army support is also being mobilized from Bengaluru, the statement said.

Chief Minister Pinarayi Vijayan said rains have caused extensive damage to life and property across the state. "The Centre has agreed to extend all help," he said.

Since more rains are forecast, as a matter of abundant caution, it has been decided to postpone the upcoming Nehru boat race on the Punnamada lake, he said.

"We call upon all to donate to the Chief Minister's Fund," Vijayan said.

Power Minister M.M. Mani, who is from Idukki, said the situation in the district was "pretty bad".

"The shutters of the Idamalyar dam were opened. We will open a shutter of the Idukki dam also," he said.

The capacity of the Idukki dam is 2,403 meters. At 12.30 p.m., when the water level crossed 2,399 meters after a gap of 26 years, one shutter of the dam was opened.

"At the moment everything is under control," said Idukki legislator Roshy Augustine.

The Malampuzha dam, which was opened a few days, sent out waters which have created havoc in certain areas of Palghat, which borders Tamil Nadu.

Water has entered houses in many low-lying areas of the district.

Earlier, Vijayan held an emergency meeting and appointed senior official P.H. Kurien to lead the rescue and relief operations.