Water Resources Minister P.J. Joseph has said that the experts of the Indian Institute of Technology, Roorkee, who held the dam break analysis of the Mullaperiyar dam submitted a report that the water level would rise to 40.30 meters downstream of the dam and 20.85 meters in the Idukki reservoir.
The water from the Mullaperiyar dam would reach Vallakkadavu within 26 minutes, Vandiperiyar in 31 minutes and Idukki dam within 128 minutes.
The expert team appointed by the Kerala Government had been asked the dam-break analysis to be conducted in areas of Mullaperiyar, Idukki, Cheruthoni, Kulamavu, Lower Periyar and Bhuthathankettu dams. The areas also extending to through the Periyar till it reaches the Arabian Sea, was also brought under the analysis.
The IIT has submitted the first part of the detailed report, extending from Mullaperiyar dam to the Idukki reservoir. The second part of the report is expected to be submitted before May.
Usually a dam-break occur when the dam is overflown due to floods in heavy rains, weak condition of the dam or due to earth quakes and landslips causing strong waves resulting in water oozing through the weak portions of the dam.
When there is a dam-break on the upstream of the main river, it could be possible for breaking the dams on the downstream portions too. The intensity of a dam-break could be reduced if advance steps taken in consideration of the quantity and force of the water flown in areas and the density and the resultant damage to the life and property of the people.
The most modern equipment to be set up is hydro dynamics stimulation modules. This will help to make an analysis of flood hydro graph, the water level in various places and the likely flow of the water in areas on the downstream.
The dam-break analysis was held using a one dimensional hydro dynamic modelling. For conducting the dam-break analysis, HEC _ RAS version 4.1.0 developed by the Federal Energy Regulatory Commission, United States was used. The support for the dam-break analysis was given by the breach guide lines provided by the Energy Regulatory Commission and the American Bureau of Reclamation.
If there was a dam-break, about half of its portion would also fell down within 12 minutes and there would be a flood situation at a maximum level of 12.41 meters per second. In such a flood situation, water would rise to a height of 886 metres in the Periyar below 50 meters of the dam and at Vallakkadavu, 854 meters and in Idukki dam 767.26 meters.
The report also said that if the dam break occurred when the water level is at 136 feet, the water level in Idukki reservoir, which is 36 kilometres would rise 20.85 meters.