Kochi in Kerala’s Ernakulam district braced for floods on Friday as the water level in the Periyar River went up after the fourth sluice gate of the Idukki dam was opened in the morning, prompting authorities to close schools and offices.The gushing waters of the reservoir, which is 130km away, has already inundated the low lying areas of the port city and posed a big threat to the Cochin international airport.“We are on a high alert. At least 4,000 people living in low-lying areas have been evacuated to relief camps. We have closed all educational institutions in affected areas,” said Ernakulam district collector Mohamed Safirulla.Periyar, the state’s second largest river after Bharatapuzha, originates from the Western Ghats and flows through the thickly-populated areas of Kochi before merging with the Arabian Sea. Authorities are worried Kochi, which is surrounded by many backwaters and water bodies, will have a face the brunt of the heavy inflow from the dams upstream. Authorities have decided to close all school, colleges and offices in Ernakulam and Thrissur districts after the water level in the river increased menacingly. Besides dotting hydel projects, the river is also the major source of drinking water to many areas including Kochi. Kochi may go thirsty as sledge from the Idukki and Idamalayar dams crept into the water-pumping station in Aluva.“Work is on a war-footing to de-silt the area leading to the pumping station. Siltation in the river increased manifold after the dam water carried enough slush. Our teams are on the job and if needed, we will seek the army’s help,” said state revenue minister E Chandrasekharan who is camping in Aluva.Several rivers are in spate following the incessant rains and all the 24 dams in different parts of the state have been opened to release excess waters. At least 26 people have been killed and many are missing as heavy rains continued to lash the state triggering flash floods and landslides. “I never witnessed such a water level in my life. Thanks to preparedness human casualty was restricted to an extent. But at the same time, we have to take a lesson from such disasters. We have to check river and forest encroachment in a big way,” said Kannan Nair, a retired headmaster from Aluva who was shifted to a relief camp in the morning.