Five columns of Army were deployed in the state's seven severely-hit northern districts, out of Kerala's 14, to help evacuate people and to build makeshift bridges even as the Indian Navy's southern command was put on alert after water level in Periyar river rose amid concern that parts of Wellingdon Island in Kochi could be inundated.

Almost all 40-odd rivers in the state are in spate, officials said.

Northern and central Kerala have been battered by heavy rains of the Southwest monsoon since August 8, which has left 29 people dead, including three today. Of them, 25 died in landslides and four in drowning. State officials said a total of 53,501 people are now housed in 439 relief camps across the state.

Tourists were barred from entering the hilly Idukki district after roads caved in at many places. Army soldiers were building small bridges to evacuate people stranded at various places in Kozhikode and Wayanad.

A red alert was issued for Idukki and its adjoining districts in view of the possibility of release of more water from the Idukki reservoir.

At least 50 tourists, including 24 foreigners, stranded at the Plum Judy resort at Munnar since Wednesday were rescued and taken to safer places, state Tourism minister Kadakampally Surendran said.

People living downstream of Periyar river in Kochi, and Cheruthoni river in Idukki have been warned of a possibility of inundation of banks.

Water level had crossed the maximum storage capacity of reservoirs of 24 out of the state's 58 dams, forcing officials to release the water by opening the sluice gates, including three of the Idukki reservoir. Two more shutters of the Cheruthoni dam, part of the Idukki reservoir, the biggest arch dam in Asia, were lifted around 7 am today.

One shutter was opened yesterday after a gap of 26 years.

This morning, Kerala Chief Minister Pinarayi Vijayan reviewed the flood situation and relief works being undertaken by the Army, Navy, Air Force, Coast Guard and the NDRF.

Due to the increase in the water level at Idukki dam, "it is essential to release water three times (more) than what was being released now", Vijayan said, adding that this will lead to rise in the water levels of Periyar river and its tributaries. He appealed to people to be vigilant.

Vijayan has cancelled all his public functions till August 12, and will monitor the situation from the state capital.

Union minister Alphons Kannamthanam said he discussed the flood situation in Kerala with Home Minister Rajnath Singh this morning. Singh also spoke with Vijayan, and will make an aerial survey of the flood-affected areas on Sunday.

"The Government of India is providing all the required assistance including services of armed forces, disaster management team and other required assistance. Any other immediate assistance requested by the Government of Kerala will be provided," Alphons said in a Facebook post.

Col. Ajai Sharma, the commandant of DSC Centre, who is overseeing relief and rescue operations, said five columns of Army have been deployed in the northern districts since last night.

"The haphazard development along the streams has affected the natural flow of rivers, which is a challenge right now," he said.

Small bridges have been constructed to evacuate stranded people in various places in Kozhikode and Wayanad areas, and rescue operations are currently underway.

"The situation is under control," he said.

Meanwhile, state Revenue minister E Chandrasekharan reviewed the flood situation and the precautionary measures to be taken in Aluva near Kochi airport and nearby areas in view of the possibility of increase in the water level following release of more water from Idukki reservoir.

Periyar river in Aluva is already in spate following release of water from Idamalayar dam, and people living in low-lying areas have been asked to be vigilant.

Cochin International Airport Limited sources said operations at the airport had not been affected.

"The operational area is intact. No cancellation of services so far," an airport spokesperson said.

Prime Minister Narendra Modi spoke with Vijayan yesterday, and offered all possible assistance to those affected.

In Palakkad district, the flood waters started receding today as the quantity of water being released from Malampuzha dam was reduced. However, many areas are still inundated and people were seen trying to save their belongings.