SEISMIC CO-EFFICIENT

It is found that while assessing the safety of this dam the expert committee had taken the design horizontal seismic co-efficient as 0.12g instead of 0.18g, The value 0.18g is the least recommended value for zone III as per IS 1893-1984 where Kerala is situated. In this context it may be noted that the standing committee set up Government of India for advising the seismic coefficient for the river valley projects recommended a value of 0.24g (Ref: Workshop on Strengthening of dams, CBIP,1989), the Expert Committee chaired by the Member (D&R) and another Chief Engineer of CWC has taken an extreme lower value of 0.12g instead of 0.24g. This extremely low value of 0.12g has incorrectly made the dam 'safe' for water level up to 142 ft. This action of the expert committee is against the guidelines published by the CWC in this regard.

It is evident that if the least seismic co-efficient for zone-III is taken for stability analysis, Mullaperiyar reservoir is not at all safe even to hold water up to the height of 136 ft.