Thiruvananthapuram: No less than 4,500 buildings along the 100 metres on both sides of the Periyar will drown in gushing waters if the Idukki dam is opened, according to official estimates. The structures include houses, schools and industries, points out the data by Kerala State Disaster Management Authority (KSDMA) based on inputs collected till last year.
The 45-year-old dam doesn’t have shutters; so the water flow is regulated by lifting the sluices of the subsidiary Cheruthoni dam. If all the shutters of the latter dam is opened the water would first reach Cheruthoni river and then the broader Periyar — the state’s longest (244 km) and one with the biggest discharge potential.
If the water level at the 550-foot Idukki dam rises by seven feet, then the shutters of the Cheruthoni dam would have to be lifted, according to the Kerala State Electricity Board, which owns the double-curvature arch dam constructed in a narrow gorge between two granite hills. The KSEB plans to open the sluice gates of Cheruthoni dam once the water level touches 2,400 feet above the sea level, sources said. Sources said that the shutters could be opened within Monday or Tuesday.
The estimate on the number of buildings has been arrived at by considering Google data and satellite-based imagery, sources said. WorldView, Ikonos, SPOT are some satellites the KSDMA relied on to make this estimate. Their images have high resolution as the satellite-based camera can zoom in into the tyre of a car parked anywhere in Idukki, revealed an official. Yet, Google data has an advantage because the often-misty weather of Idukki tend to blur satellite images.
Also read: After 26 years, Idukki dam shutters to be opened on Aug 3-4
The National Data Centre would, when need arises, buy pertinent images from foreign companies and pass them over to the KSDMA, which was formed on the basis of a 2005 Act and is headed by the chief minister.
It is another matter why officials should buy images from firms abroad when the country has a space agency of its own, ISRO. Authorities say "each satellite has a specific working capacity, which, in some areas, could be better than that of the ISRO. For instance, American DigitalGlobe’s 2001-launched high-resolution commercial earth satellite called QuickBird. Its images are expensive."
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