Monday, January 9, 2012


Prof.T.Shivaji Rao, Director, Center for Environmental Studies, GITAM University, Visakhapatnam.
Phone: 0891-2504902 and 2738211 
 (extracts from a  presentation made by Prof.T.ShivajiRao) [under estimates of floods]  {Iyengar & Experts]
[ CWC misleads on safety while experts present  the TRUTHS] 
[ Seismic potential survey  not  conducted at Dam to detect hidden faults as in Portland city] 
[Section of Mullaperiyar in Perspective Figure and News on Dam] 
[[Himanshu Thakkar's interview on Decommissioning,CWCet.are good]
For assessing the safety of Mullaperiyar dam 3 goals of public safety must be satisfied as per the modern state-of-art used for design of the dams.  The first goal is based on the geological foundations , seismic potential and seismicity of the area. The second goal pertains to structural safety of the dam based on maximum credible earthquake including hydrological safety and spillway design flood.  The third safety goal for the dam pertains to the environmental safety that comprises on risk analysis, dam break analysis, emergency response, disaster management including emergency evacuation plans and cost benefit analysis.  In the case of the 116 year old Mullaperiyar dam none of these safety criteria was considered.  The controversy about the Mullaperiyar dam is based upon the contention of the Kerala state that the dam is in a deteriorating state and its imminent collapse causes avoidable killing of 35 lakhs of Keralites due to a wall of flood.  In order to avert this disaster waiting in the wings Kerala insists on construction of a new dam to provide security of life for the Keralites while assuring uninterrupted irrigation water to Tamilnadu as per the agreement between the states. 
But Tamilnadu is suspecting the intentions of Kerala in planning for a new dam which may be placed under the control of Kerala that may soon curtail the existing Periyar water diversion into Tamilnadu.  Thus Tamilnadu is rejecting the demand of Kerala for a new dam on the pretext that the aged Mullaperiyar dam is almost as strong as a new dam due to the remedial strengthening measures implemented by it.  But if the existing dam were to burst for several reasons even Tamilnadu cannot get Periyar water and consequently lakhs of Tamilnadu agriculture fields will become barren lands that may lead to avoidable suicides of thousands of farmers and farm workers.  Tamilnadu is ignoring the fact that their costly strengthening measures produces only a composite dam and not an integrated and strong dam.  The dam cannot withstand the stresses resulting from peak ground accelerations due to a 6.5 magnitude earthquake at a shallow focal depth in close proximity of the dam.  Even a strong Koyna dam cracked in some parts in 1969 due to an earthquake of 6.5 magnitude and caused serious damage
Moreover the dam has also been under-designed for hydrological safety because the historical maximum flood is 86 lakh cusecs and the design flood for spillway discharge is 1.22 lakh cubic ft. per second (cusecs) .  In United States safety of dam is reviewed  every 5 years to decommission hazardous dams and to strengthen the useful one by implementing remedial measures for strengthening them.    In case of Mullaperiyar dam the extreme flood magnitude in terms of safety works out to 2.44 lakh cusecs based on the mathematical formulations and the envelope curves connecting extreme floods with catchment areas published by the International Commission on Large Dams (ICOLD) under the guidance of  experts like Prof.L.Berga, Chairman, ICOLD and Lempererie, Chairman of French National Committee on Large Dams.  Moreover the impact of climate change is causing both the intensity and duration of cyclones that magnify the floods.  Particularly in thickly forested river basins.  For instance the October  2009 are extreme flood of 26 lakh cusecs at Srisailam dam on Krishna river constituted 2.7 times the historical flood and twice the maximum spillway design flood.  Since Mullaperiyar dam is thus under-designed both from seismological and hydrological safety aspects this dam is inevitably bound to collapse irrespective of the pronouncements of the engineering experts who could not stop the collapse of more than 40 dam bursts in India including the masonry dams of Tigra in Madhya Pradesh, Kundali in Maharashtra, Chickhole in Karnataka and Kadhakwasla in Maharahstra.  According to the Environmental Protection Act the dam safety studies including disaster scenarios, emergency response systems, emergency evacuation schemes and cost-benefit analysis reports have not been prepared consequently the people and the Governmental decision making bodies  have been disabled to come to a scientific decision on the safety of the Mullaperiyar dam and that it is why the Tamilnadu Government fails to read the writing on the wall and thereby indirectly promoting a man-made catastrophe like the Bhopal disaster inspite of the forewarnings by several experts.  If the Mullaperiyar dam collapses sooner than later it will cause not only loss of lifes of lakhs of people but also causes an economic disaster paving the way for economic bankruptcy of the states and the nation.  Since Mullaperiyar dam is a prescription for disaster it must be prevented by the whole national by exerting pressure on the Prime Minister to resolve the problem by building a new dam even without dismantling the existing dam by forming a corporation on the lines of  the one used for building Tehri and Sardar Sarovar Project.

River   & Basin                                            : MullaiPeriyar River  &  Periyar Basin

Location                                                         : Lat 9o 03’ 20”   Long: 77o 08’ 45”

Construction Period                                      : 1887-1895

Cost                                                                 : 43.00 lakhs (18 crores for strengthening work)
Catchment area                                       : 232.60 sq.miles (602.4
Water spread area                                   :10.21 sq.miles (28.44
Design Flood                                            : 1.22 lakh cusescs (3454 cumecs)
FRL                                                          : 152’ (+2861’ {(or) +872.285 m}
MWL                                                        : 155’ {+2864’ (or) +873.20m}
Dead Storage Level                                  : 104’ {+2831‘ {(or) +857.65m}
Capacity of Reservoir at FRL                 : Gross 15,682mcft (444.06 mcum)
Vents                                                       : Old   : 10 Nos (36x16) or (10.97x4.88m)
Additional                                               :New : 2 Nos (40’x16’) or (12.19x4.88m)
Type                                                        :Old : Vertical Lift Shutter
                                                                : New: Radial Shutter
Crest Level                                             : 136’ (+2845ft) or 867.405m
Platform Top Level                                :177.65’ (+2886.75’) or 880.105m
Max.discharge                                       Old : 86,000 cusecs (2483.54 cumecs)
                                                               New: 36,000 cusecs(991.08 cumecs)

Mullaperiyar dam  design underestimated Roy Mathew
Actual flood level is much higher, says Government
THIRUVANANTHAPURAM: The State Government's finding that the Central Water Commission (CWC) underestimated the probable maximum flood (PMF) in Mullaperiyar catchment when it recommended strengthening measures for the dam back in 1979 heightens public concerns about the safety of the dam, observers familiar with the issues involved say.
(PMF is the flood that can be expected from the most severe combination of critical meteorological and hydrologic conditions that are reasonably possible in a region.)
This is something that had not been taken note of by the technical committee of the State when it recommended in the Nineties that the water level in the reservoir should not be allowed beyond 136 feet. Nor had these arguments been presented before the Supreme Court.
However, Minister for Water Resources N.K. Premachandran raised this point during the talks convened by Union Minister for Water Resources Saifuddin Soz in New Delhi in December.
The key point in his argument was that the CWC had recommended a PMF of 6,003 cubic metres per second (cumecs). However, an actual flood in 1943 was of 8,453 cumecs. This means that water will overtop the dam if the maximum possible flood occurs. The Government notes in a communication sent subsequently to Mr. Soz, listing Mr. Premachandran's arguments, that for any dam, particularly for masonry or composite gravity dams, flow of water over the top of the dam is the most dangerous situation. It results in collapse of the dam as a result of sliding or overturning. 
Hydrological safety of Mullaperiyar is highly under-estimated :
Because this is such a crucial safety aspect of the dam, the pattern followed uniformly in all dams in the country is to identify the maximum observed flood that has occurred in the catchment area. Then, this figure is significantly boosted up and the PMF identified from this boosted-up figure.
In the case of Mullaperiyar dam, the maximum flood that took place in the reservoir was 8,453 cumecs. However, curiously, for the purpose of determining the PMF, the then Chairman of CWC recommended 7,249 cumecs, a figure lower than this maximum amount. This recommended figure was again lowered for reasons unknown to 6,003 cumecs.
Even with this artificially lowered figure, the water will flow over the top of the dam but for the parapets. Not only this but also the siltation in the dam will further contribute to the rising of the mean water level so that water flows over the top of the dam. 
Seismic potential for Mullaperiyar dam is highly under-estimated:
The Government also adds that while assessing the safety of the dam, the expert committee of the CWC had taken the design horizontal seismic co-efficient as 0.12 g instead of 0.18 g. The value 0.18 g 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 by the Union Government for advising the seismic coefficient for the river valley projects recommended a value of 0.24 g.
"This extremely low value of 0.12 g 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."


  1. മുല്ലപ്പെരിയാറിനെ കുറിച്ച് നല്ലൊരു റിപ്പോര്‍ട്ട്‌. സമയമുള്ളവര്‍ സമയം എടുത്തു വായിക്കുമല്ലോ.