Train services were disrupted at many places and rail service between Thiruvananthapuram and Kanyakumari was suspended after main bridges were swept away in the gushing waters.
Operations of global and domestic flights were earlier suspended till 2pm on Wednesday but authorities chose to shut the airport till 2pm on Saturday after reviewing the worsening situation.
The Idukki dam floodgates were reopened late on Tuesday as the water level in the Periyar river and its tributaries flowing through Ernakulam and Thrissur districts rose menacingly. Power Minister M.M. Mani told the media here that the government was fully geared to help those who had been displaced.
The official added that authorities had issued a "red-alert" warning in all 14 districts of the flood-ravaged state, with heavy downpours expected over the next 24 hours in numerous worst affected areas.
The shutters of the Mullaperiyar dam in the Idukki district was opened at 2.30 am on Wednesday following the rise in water levels at the dam.
Munnar was isolated by landslips and the surging waters from the Mattupetty dam fed by copious rains in the catchment areas. We are working hard on draining out the storm water.
Several districts of the state including Idukki, Kozhikode, Kannur, Wayanad and Malappuram continue to witness landslides and flood. "The neighbouring states have been helping us and we need their help in the future too", added the chief minister.
Kerala is battered by the monsoon every year but the rains have been particularly severe since August 8, flooding hundreds of villages and prompting the authorities to suspend flights in and out of the region.
Authorities are maintaining a close vigil especially in Idukki district as the shutters of the Mullaperiyar dam were also opened at 2.35 am after its water-level crossed 140 feet. Unabated rains have forced the state government to do away with the official "Onam" celebrations and the amount set apart for the goal would be utilised for relief operations. "We're keeping all this in mind but our priority is to get drinking water to the people".
More than 1.5 lakh people have been lodged in relief camps across the state, Vijayan said.
In Malappuram district, rains pushed up the water level in the Chaliyar river, forcing families living along its banks to shift to relief camps.
The state last saw such devastating flooding in 1924. The government also made a decision to do away with annual "Onam" celebrations being organised by the state and to utilise the amount for relief measures, he said.