Director, Centre for Environmental Studies,
For Bio-data, http://www.bagchee.com/BookDisplay.aspx?Bkid=B34014
http://cgwb.gov.in/watershed/PERIYAR.jpg (detailed sub-basins map .....?)
http://cgwb.gov.in/watershed/cdperiyar.html (detailed sub-basin areas ....? )
http://www.geocities.com/prof_shivajirao/cloudseedingeffective.html (Details on cloud seeding)
http://www.mapsofindia.com/maps/india/seismiczone.htm [KERALA in ZONE-III ]ABSTRACT
The Mulla Periyar dam was built by the then Madras Government by taking the land on Periyar River basin on lease for 999 years from Travancore state. Tamil Nadu diverts about 640Mm3 (about 22.5 TMC) of water from the Periyar Reservoir annually for generation of hydro-power and irrigation of lands in Madurai district . It is argued that if storage depth of Mullaperiyar dam is increased from 136ft to 152 ft. Tamil Nadu will get additionally 320 Mm3 (11.25 TMC)of water from the reservoir and consequently the storage of Idduki reservoir below this Periyar Dam gets reduced from its present capacityof about 2000 Mm3 (70 TMC) to a lesser value. In addition the Dam safety and Disaster management problems have assumed crucial importance in view of the recurring earthquakes and the frequent increases in the seepage of water through this aging dam.
While Tamilnadu is demanding for raising the reservoir level to 152 feet for taking more water to meet the growing needs of the farmers,Kerala is insisting on maintaining the reservoir level at 136 feet to ensure the safety of the Dam in view of its deterioration due to age.The problem must solved amicably because the people of both the states are misunderstanding each other resulting in social unrest.The people of Tamilnadu must be happy as kerala has agreed to continue to maintain the reservoir level to 136 feet even if if it werwe to result in a collapse of the dam due to a maximum credible accident for one reason or the other in course of time.
Taking advantage of this position,Tamilnadu must demand the Union Government not only to build a New Dam to replace the old one,but they must insist on the Prime Minister to direct the Union ministry of Earth Sciences to conduct cloud seeding operations as practised in China and 40 other countries to constantly maintain the reservoir level at 136 feet so that the Tamilnadu Government can instal adequate pump sets to lift all the required water within the 6 months period of incessant rains of South West monsoon and store that water in newly constructed reservoirs in Theni and Madurai Districts for timely supply for irrigating vast stretches of lands in South Tamilnadu to eliminate poverty and restore its agricultural prosperity as envisaged by the old British Rulers.The Chief Ministers of both kerala and Tamilnadu must jointly work towards this goal of mutual cooperation for national prosperity.
Inspite of the judgement given by Supreme Court on raising the height of the Mulla Periyar dam the state of Tamil Nadu and Karnataka are still not able to come to a mutually agreed solution to resolve the crisis. Hence an attempt is made here to enlighten the educated citizens of both the states to make a correct assessment of the problem based on scientific and technical propositions on the relevant factors that govern safety of the dam and the environment.
BRIEF HISTORY OF THE DAM:
http://expert-eyes.org/mulla1.html (See Mullaperiyar dam-view)
The Periyar dam is the first Surkhi concrete dam in a “V” shaped gorge in the Western Ghats over the west flowing Periyar river. This Periyar river is a perennial river which rises from the Sivagiri group of hills in Kerala state and flows through Kerala state and joins the
ENSURING SAFETY OF THE DAM WITHOUT JEOPARDISING INTERESTS OF BOTH STATES
In order to resolve the controversey between Tamilnadu and karnataka,a scientific assessment of the problem must be made from several aspects
The earthquakes of magnitude 4.5 at Nedumkandam(1988), 4.3 at Wadakkanchery (1994) and the latest earthquake of magnitudes 5 that occurred in Periyar basin (12-12- 2000) clearly justify the views of seismologists that the seismic activity has recently increased and hence the tectonic behaviour of region must be assessed to know the seismic safety of Mulla Periyar, Iddukki and other dams in the region. In USA the geological survey uses aircraft with magneto-meters for studying the magnetic anomalies and detect the hidden faults to assess the seismic hazard potential in the selected zones. The continuing work of the dedicated and intelligent earth scientists is helping to protect the lives and properties of citizens in different regions from the earthquakes that are inevitable in the near future. But unfortunately the Indian experts without undertaking such investigations on seismic potential of Mulla Periyar dam are jumping to make unscientific pronouncements on the safety of the dam although such expert opinions are likely to present risks to the life of lakhs of people in Kerala.
The probability of failure of a dam depends on factors like seismicity of the area, spillway capacity, nature of foundations, seismic design quality of construction, feasibility of disaster management, bombing by terrorists or enemy countries. About 10% of the dams failed in India and abroad and about 2% of them are reported to have collapsed. The Vaiont dam in Italy failed in 1963 due to the collapse of the mountain slopes around the reservoir basin due to a series of medium earthquakes. Some dams in the western ghats of Maharashtra and Karnataka have also collapsed. About 2000 dams have been identified by the US experts as unsafe and it is estimated to cost $1000 million to rehabilitate them. Under the dam Safety Acts in USA and Canada, the risk analyses and dam-break scenarios are used as tools to assess the hazard potential of a dam as it provides firstly the data required for scientific estimation of spill way capacity and secondly to predict the flood wave depth and flood wave arrival times for identifying the villages and towns that could be drowned by the flash floods due to the collapse of the dam. Thus flood management in preventive terms means dam safety and in protective terms flood plains management. According to the International Standards (ICOLD –57, Bulletin46) seismic safety of the dam ensures that firstly the dam does not suffer significant damage due to an anticipated earthquake and secondly the damage to the dam is limited and no catastrophic failure occurs leading to uncontrolled release of water due to a maximum credible earthquake.
While studying the Environmental safety of Mulaperiyar dam, two expert committees, one appointed by the Kerala state and another by the union Government presented contradictory recommendations on safety aspects of the dam. A perusal of Newspaper reports on the findings of Expert Committee of the Central Government indicates that the report gives a false impression about the safety of Mulaperiyar dam and naturally the farmers of Tamil Nadu have become suspicious about the genuine grave concerns of Kerala on the colossal environmental damaging impacts consequent to the proposed increase in the height from 136ft to 152 ft of the century-old Mulaperiyar dam. Safety and Environmental hazards of Mulaperiyar and other dams like Iddukki are questions of life and death to Kerala and such issues are too serious to be blindly left in the hands of Experts since they involve not only the technical but also the major social problems. Since most Keralites are intellectual giants, it is necessary to create proper environmental awareness on this controversial problem so that the people can safeguard their right to life and the environment as envisaged under section 51(A) of the constitution of India.
WHO IS AN EXPERT? HOW SHOULD AN EXPERT OPINION BE EVALUATED?
According to law, an expert opinion becomes relevant for right decision, if only it conforms to certain fundamental norms. According to sec.45 of the Evidence Act, a person specially skilled, is considered as an expert. When the court has to form an opinion upon a point of science, art or engineering, the opinions upon that point of such persons who are specially skilled in such science, art or engineering are relevant facts. But an expert in order to become a competent witness need not acquire special knowledge or skill professionally because it is enough if he made a special study of the subject or acquired special experience therein.
Before the testimony of a person becomes acceptable his competency as an expert must be proved, may be by showing that he possesses the required qualification or that he has acquired skill therein by experience. An expert should be subjected to cross examination because like any other witness, the expert is fallible and the real value of his evidence consists in the rightful inferences which he draws from what he himself has observed and not from what he merely surmises. Facts which are not otherwise relevant become relevant, if they support or overthrow the opinion of experts when such opinions are relevant.
Where the opinion of an expert is to be acceptable, the grounds or reasoning upon which such opinion is based may also be inquired into. Opinion is no evidence, without assigning the reason for such opinion. The correctness of the opinion can better be estimated in many instances when the reason upon which is it is based are known. If the reasons are frivolous or inconclusive, the opinion is worth nothing. While the value of non-expert witness depends upon the credibility of the witness (i.e. his inclination and capacity of telling the truth), the value of opinion of an expert depends largely on the cogency of the reasons on which it is based, and the competency of the expert to form a reliable opinion. An expert opinion cannot be the basis for decision-making, unless the expert opinion is also corroborated by other evidence.
GUIDELINES ON SAFETY OF DAMS(ICOLD, IFC, USA, CANADA etc):
a) International Commission on Large Dams(ICOLD):
According to ICOLD publication of dam safety (1996) , it is the extreme events that are of interest for dam safety, that is accidents and it involves the specification of the magnitude of the design flood and the design earthquake at the design stage. According to ICOLD in practical terms, there are conditions that (although essential for producing a scientifically based design) are not readily capable of being grasped by any rigid pre-set pattern of investigation and statistical analysis alone, human judgement on where and what to look for must be brought to bare, but decisions based on judgement may involve major risks in design and consequently when performing the monitoring and maintenance work.
Examples of human behaviour which, according to ICOLD lead to serious accidents are:
1) Non-preparation for accidents and lack of emergency planning
2) Risk management, subordinated to speed of work on the dam
3) Unclear responsibilities including failure to assign identified tasks to suitably specified individuals
4) Lack of feedback
5) A sense of infallibility, an over simplistic approach or a break-down in communications between disciplines within the design team.
To avoid the above mishaps the design team must be not only highly structured but also open minded so that they can avoid the traps arising from such behaviour and are capable of making allowance for the limitations and uncertainties involved in the multi-disciplinary approach.(Most of these factors hold good in the case of Mulla Periyar and other dams)
Out of 36,000 large dams in 1998, 300 reported accidents. Dam failure rate is about one percent and the annual failure risk for any dam is 10-5. The overall risk for a dam is due to uncertainties like design-flood, design-earthquake, properties of material in the dam, and poor foundations. Risk calculations for dams are made in Canada, Australia and Norway as they make it possible to adapt the level of risk to suit the potential downstream consequences. It is the duty of the project authorities and their experts to inform and educate the concerned public down stream of the dam on the risks involved so that the Government can plan for safety of the dams, the environment and the people.
b) International Funding Agencies:
The International Finance Corporation asserts (www.ifc.org) that to ensure the safety and the life of any dam the project authorities must take the full responsibility. For large dams above 15 meters in height, it requires
a) Both technical and environmental reviews by independent panel of reputed experts throughout the investigation, design, construction and operation of the dam.
b) Preparation and implementation of detailed plans for construction, instrumentation and operation including an emergency preparedness plan.(No such plans made for Tehri)
The project proponent must appoint 3 or more independent experts with expertise in the various technical fields relevant to the dam safety aspects. For high hazard dams the experts should be internationally known in the field of dam safety that not only pertains to the physical structure but should also be concerned about the risk of catastrophic or incremental harm to the safety and welfare of downstream human populations and productive systems.
An environmental impact assessment (EIA) of the dam would examine the effects of a catastrophic failure of the dam and its long term impact on the downstream environment. For large dams emergency preparedness plan must be prepared and submitted. This plan must specify the responsibilities of parties when the dam failure threatens downstream life and properties and it should include maps outlining the inundation levels for various emergency conditions, flood warning system and procedures for evacuating people from threatened areas. The safety of the dams require that the project authorities must inform the local people about the risks and the safety aspects of the dam and abatement actions by treating them as environmental problems.
Environmental Assessment (EA) evaluates the potential environmental risks and impacts of a dam in its area of influence and for this purpose EA examines project alternatives, identifies ways of improving the project selection, siting, planning, design and implementation by preventing and minimising adverse environmental impacts.
The project authorities shall also engage an advisory panel of independent, internationally recognised environmental specialists to advise on all aspects of the project relevant to environmental assessment. The project authorities must consult the people likely to be affected about the environmental impacts and take their views into account during and after preparation of EA.
A hazard assessment is an instrument for identifying, analysing and controlling hazards associated with presence of dangerous substances and conditions in a locality and dams which store water in high seismic zones are hazards for people likely to be affected in case of a manor accident. But risk assessment is an instrument for estimating the probability of harm occurring from the presence of hazardous situations and risk assessments are essential for dams planned in locations vulnerable to seismic activity or other natural or manmade hazards. Thus risk assessment is treated as part of the environmental assessment documentation.
EA reports cover analysis of alternatives and they make comparison of feasible alternatives to the proposed project site, technology, design and operation including the option of a “no project situation”. Environmental Action Plans cover mitigation measures, monitoring and institutional strengthening to eliminate or minimise environmental or social impacts.
c) Dam Safety in USA :
Dam safety regulations are implemented by several states in USA. For example the dam safety in Alaska is covered by Alaska statute 46.17 and 11 AAC 93, article 3 and dam safety became effective in May 1987.
According to old English common law the capture of water in itself is a hazardous activity. Therefore whoever captures the water is generally held responsible for any damage caused by the capture or release of the water and so the dam proponent is ultimately responsible for the safety of the dam. According to the regulations in Alaska State, USA. A high dam must have an emergency action plan which details the actions to be taken in the event of a dam failure, potential dam failure or other emergency involving the dam. The plan must have an inundation map and describe the warning and evacuation procedures for affected persons. The plan must describe the procedures for co-ordination with the local emergency management agency and the dam safety and construction wing that regulates construction and operation of the dams.
UNSAFE MULLA PERIYAR DAM?
The experts group of Central Water commission according to Mr.K.Paramesaran Nair alone representative of Kerala Government had floughted the fundamental rules of dam safety. Mr.Nair says that 95% of the water from the Mulaperiyar reservoir is now given to Tamil Nadu which wants the balance of 5% which amounts to 1.2TMC and for this purpose Tamil Nadu demands to raise the height of the dam from the present level of 136ft to 152ft. or even 145ft. and this demand poses threat to the public interests of Kerala. Keralites warn that if the height of dam is increased and if an accident occurs to the dam the flash floods will destroy Kumili town and thousands of people will perish in four districts downstream of the dam in Kerala state. Besides 10,000 acres of forest land would be submerged and 10,000 tribal families will be deprived of their food and shelter. The attempt to increase the height of the dam and the move to construct another dam is not based on scientific grounds. The claim of Tamil Nadu that the dam has enough strength to hold more water is not based on scientific grounds.
The annual leaching from the dam is 30 tons of water per year and cement grouting was done. The Probable Maximum Flood (PMF) used in the design of Mulaperiyar dam was 2495 cumecs and it was revised to 6000 cumecs as suggested by Central Water Commission. Idukki has a PMF of 8000 cumecs and Idukki would not be able to handle a major inflow of 6000 cumecs, if Idukki itself has water upto FRL or near to it. If both the projects are subject to flooding at the same time is pose a threat to the dams that means even if Mulaperiyar does not fail. Since several small rivers while diverted into Idukki subsequent to its completion. The failure of Mulaperiyar dam could be catastrophic for Idukki project. Idukki dam that was built to hold 2000million cubic meters of water (70 TMC) will have to absorb flash floods of 443 million cubic meters (15 TMC) from 50 kms away and if it fails hundreds of towns and villages of Periyar basin in Kerala will be wiped out if the dams of Idukki failed. Idukki w as designed for PGAh of 0.05g and PGAv of 0.025g. It means that the dams cannot withstand earthquakes of higher intensity expected in the area in the near future. Lower Periyar dam downstream is designed for PGAh of 0.1g. However landslides in the catchment due to recurring earthquake tremors and intense rains can cause failure of the dams as had happened in the case of Vaiont dam in Italy in 1963. The scientific studies indicating unstable hill slopes and heavy siltation of the reservoirs indicate the hazards waiting in the wings.
Medium earthquakes like the once that occurred in Periyar basin have produced very high Peak Ground Acceleration (PGA) in several Geo-tectonic environs. For instance the Ancona earthquake of 4.6 magnitude in Italy (1972) produced PGA of 0.61 and the Oroville quake in USA (1975) of magnitude 4.6 produced PGA of 0.63 and the Salvador earthquake (1986) of 5.4 magnitude produced a PGA of 0.70 and the Cerro earthquake of USA (1987) of magnitude 5.5 produced a PGA (horizontal) of 1.12g and a vertical PGA of 0.61 and hence the Mulaperiyar dam which was not designed to withstand any earthquake can never be expected to be safe particularly when it is century-old and located in a highly earthquake prone zone.
If the design, construction, operation and maintenance of the project works placed in the hands of Tamil Nadu and the beneficiaries are Tamil farmers of Madurai and the potential victims of the catastrophic failure of the dam are in hundreds of villages and towns of Kerala, it is impossible to preface the risk analysis and Disaster management reports for emergency evacuation of people likely to be killed due to a maximum credible accident to one or more dams on Periyar river. In the absence of these basic reports, the recommendations of the Expert committees appointed by the Central Government to study safety aspects of Mulaperiyar dam become null and void.
Failure of dam also occur due to the following causes:
1.Liquefaction of the materials used in the dam.
2.Liquefaction in the foundation soil
3.Wrong estimation of the peak ground acceleration due to wrong assumptions on seismic potential of the area in terms of magnitude, intensity and methods followed for estimating effective Peak Ground Acceleration
4.Prediction of deformations and stresses from earthquake loading
5.Inability to make necessary modifications in the size of the dam that will provide an acceptable response in case the predicted deformations or stresses are intolerable due to revised increases in seismicity of the area during project construction.
6.Inability to estimate performance of the dam and foundation characteristics by comparison with case histories of dam failures
Other modes of dam failures include:
7.Slope failures induced by ground motions
8.Sliding of the dam on weak foundation materials
9.Disruption of dam by major fault movement in the foundation
10.Loss of freeboard due o differential tectonic movements
11.Loss of freeboard due to slope failures or soil compaction
12.Piping failure through cracks induced by the ground motions
13.Overtopping of dam due to seiche in the reservoir
14.Overtopping of dam due to slides into the reservoir
15.Overtopping of dam due to failure of spillway or failure of dams upstream.
The water level in Periyar was reduced from 152ft. to 136ft. in 1979 due to doubts raised about the strength of the Century-old structure. When American experts are reviewing the safety of all their dams in the light of the latest tremors and are dismantling some old dams, strengthening some weak ones and redesigning some more by reducing their storage levels so that emergency evacuation measures become feasible for implementation during collapses of dams to minimise loss of lives and properties, how can some Indian experts who have no indepth knowledge on seismic safety of dams venture to vouchsafe for the safety of Mulla Periyar dam without making any scientific analysis pertaining to all the above relevant factors as followed in the developed countries in this regard?
SOLVING THE PROBLEMS OF KERALA AND TAMIL NADU
BY CLOUD SEEDING ON EITHER SIDES OF THE WESTERN GHATS:
While the farmers of Tamil Nadu are demanded for increased water supply by raising the height of Mulla Periyar dam, the Kerala people in the down-stream valley are demanding that their right to life and environment should be protected as per the constitution. Both the demands of Tamil Nadu and Kerala can be met by using the latest technologies for cloud seeding followed in several countries like USA, Canada, Australia, Israel, France, China, Indonesia, South Africa and Russian states. Artificial rain making is a proven technology in India and abroad as it increases annual rainfall by 15 to 30 percent.
CHINA IS WORLD LEADER IN EXTRACTING ADDITIONAL 1400 TMC PER YEAR BY CLOUD SEEDING OPERATIONS
In China almost all the municipalities, districts and states are regularly conducting cloud seeding experiments on both warm clouds and cold clouds not only to augment annual rainfall but also to suppress the hailstorms to avoid enormous economic damage to crops and properties. China is employing about 30,000 technicians every year to increase the annual rainfall by about 30% amounting to about 1400 TMC (about 40 billions cubic meters) at the cheapest cost .http://subs.nzherald.co.nz/topic/story.cfm?c_id=281&objectid=10385522
Thus the annual additional rainfall produced by China with the whole hearted cooperation of the Communist Party workers, patriotic scientists and Ministers is more than twice the annual water flow in the mighty Cauvery rivers whose annual flow is a serious bone of contention among the basin states of Kerala, Karnataka, Tamil Nadu and Pondicherry whose elected legislators and Members of Parliament are not seriously bothered to promote public health and welfare by making available more water by copying the example of China which has taken up cloud seeding as the last and most potent weapon to fight the recurring droughts and thereby eleminate poverty and suffering among the millions of poor people who elected them to promote their prosperity and quality of life.
Even the King of Thailand is also so highly patriotic and loves to this all the sufferings of the farmers and farm workers consequent to recurring droughts. He is keenly interested in personally handling cloud seeding operations to squeeze additional rain fall every year from the sky water contained in the atmospheric clouds in an abundant extent amounting more than 10 times the freshwater contained in all the rivers on earth. Many patriotic leaders of other countries are requesting Thailand and China to help them to implement cloud seeding operations to harness not only the surface and ground waters but also the abundant water resources of the sky as contained in the seedable clouds as can be seen from the following website:
Further by over seeding the clouds that precipitate over the Arabian sea,they can be transported by the winds over to the Western Ghats in enlarged sizes and numbers and when they are re-seeded at suitable places they naturally give additional rainfall on both the Eastern and Western sides of the Western Ghats many times during the South West monsoons and periods of depressions and cyclones. Thus the annual rainfall can be increased by artificial rain making as suggested by the famous Irrigation Engineer Dr.K.L.Rao in his book on Indias Water Wealth. This will eliminate the need to raise the height of Mulla Periyar dam. Alternatively a new concrete or arch dam can be constructed in close proximity of the existing dam so that more water obtained by cloud seeidng operations can also be stored for utilisation by the Kerala state to produce additional hydro-electricity at a cost benefit ratio of 1:30 for promoting industrial development. This additional rain water that can be obtained by cloud seeding every year can also be used by Tamil Nadu state Government by diverting the water through another additional tunnel and store it in one or two reservoirs to be consturcted in the upper catchment areas of Vaigai river so that even the farmers of Ramanathpuram district can improve their own agriculture. For this purpose the Chief Minister of both Kerala and Tamil Nadu should come to an understanding in choosing appropriate alternate methods of providing more water to their sttes by not only conserving their own conventional surface and ground water resources but also by taping the new water resources in the atmospheric clouds. The Government of India and the Planning Commission may be requested to help the states to conduct cloud seeidng operations just like the Chinese Government is helping all the other provinces to augment their water resources for improving the quality of life of the people.
ROLE OF INTELLECTUALS :
The Kerala intellectuals and educational institutions must organise public debates on these environmental and safety aspects of the proposed project and its alternatives to create adequate awareness about the problems so that the people can exert pressure on the state and Central Governments to take scientific decisions in resolving this sensitive problem for ensuring sustainable development of both Kerala and Tamil Nadu.
http://www.bbc.co.uk/dna/360/360/A784794 (Alamatti Dam)
EXTRACT FROM HINDUSTHAN TIMES DT.9-1-2001:
Kerala, TN quakes widen cracks in Mullaperiyar dam
(Thiruvananthapuram, January 8)
THE MULLAPERIYAR dam developed major cracks following Sunday's moderate tremors. Certain areas of south Kerala experienced mild after-shocks on Monday.
This is the seventh tremor to rock Kottayam and Idukki districts since December 12. Sources in the Mullaperiyar dam office said the cracks that had developed during the December 12 quake had widened after yesterday's jolts. The seepage had intensified and removed plasters at many points.
The dam is a subject of disagreement between the two neighbouring states of Tamil Nadu and Kerala. Tamil Nadu wants to raise the height of the dam from the existing 136 feet to 156 feet. However, Kerala has opposed the proposal saying that the 100-year-old dam was situated in an earthquake-prone area and quake-proof measures were not adhered to while constructing the dam.
Recently, a central expert team had recommended that there was no harm in raising the dam height to 142 feet.
Fresh tremors: Mild tremors, measuring up to 3.1 on the Richter Scale, were reported from parts of Kottayam and Idukki districts of Kerala in the early hours today, official sources said here.
According to sources, the tremors occurred four times between 1.10 am and 4.10 am in parts of Meenachil and Kanjirappally taluks accompanied by a booming sound.
Panic spreads: According to reports from Kottayam and Idukki, panic-stricken people had started taking precautionary measures. Many people stayed in tents throughout last night. Besides, contradicting views by seismologists and geologists have added to their confusion. Scientists have differences of opinion about the epicentre and magnitude of yesterday's quake. In Pala, the tremors had brought gushing streams from an abandoned bore-well.
"It is said that 95 per cent of the dam's water is now given to Tamil Nadu and it wants the balance of five per cent which amounts 1.2 tmc. But this is a very dangerous demand, according to him. Tamil Nadu maintains that strengthening measures have been carried out in the dam and therefore it is safe to raise its height further. It also stated that drilling was conducted upto 30 ft on the foundation rock of the dam and cable anchoring was held at 94 places."
After 1979, when the water level was maintained below 136 feet, as much as 11.219 sq km of land was exposed. New settlements and activities were developed in such areas in the adjoining Kumily during the last 21 years. Increasing the reservoir level now will affect seven sites where there are over a thousand households with a population of between 3,500 and 4,000 people. Both tribals and non-tribals will be affected when their houses and agriculture lands are submerged, the study says. [From The HINDU,11-11-2000]
Extracts from THE HINDU dated 12-01-2007
Figures for Mullaperiyar dam underestimated :Roy Mathew
Actual flood level is much higher, says Government
Disparity in the PMF recommendations of the CWC in
Relation to Maximum Peak Inflow presented by Kerala
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. (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 < xml="true" prefix="st1" namespace="" ns="urn:schemas-microsoft-com:office:smarttags">
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.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."
some of the objections raised by kerala are very valid.In fact my articles presented in the above web sites on the proposed Polavaram dam and the Sardar sarovar dams,it can be seen that the Central water Commission who should guide the states on safety of Dams is not discharging its responsibilities in public interest on highly scientific lines.For instance,as per international standards,if the historically recorded peak flood in Mullaperiyar in 1943 was 8,453 cumecs,the PMF should have been taken atleast 1.5 times that value and estimated at about 12,680 cumecs or based on the failure of the Machhu Dams in Gujarat PMF value should have been taken at bout 17,000 cumecs .Sardar Sarovar dam and Mulla periyar dams are located in the same seismic Zone-III and hence the same seismic coefficients must be applied to ensure safety of the dam.Hence the views of kerala state are justified and need to be investigated before taking a scientific decision as per the criteria cited in my articles on safety assessment of major dams
PROF.T.SHIVAJI Rao is presently the Director, Centre for Environmental Studies, GITAM College of Engineering, Visakhapatnam-530 045. Formerly Principal, College of Engineering, Andhra University, Waltair, P.W.D Engineer at Nagarjuna Sagar dam. As an International Expert he was invited by the Royal Swedish Academy of Sciences in 1976. He delivered key-note addresses at two international conferences at Khatmandu, Nepal in 1979 and 1997. He is the recipient of Best State Teacher Award for 1986-87 and the Swami Pranavananda .National Award for 1991 of the University Grants Commission on Ecology and Environmental Sciences. He was a member of the A.P.State Pollution Control Board and Chairman of its Technical Committee and was member of the Environmental Appraisal committees of the Union Ministry of Environmental and Forests for Industries and River Valley projects and during this period had an opportunity to review the Environmental Impact of Tehri Dam as a member of the Bhumbla Committee and recently as a member of the high-power committee on seismic safety of Tehri dam appointed by the Government of India in April 2001
for bio data: http://www.geocities.com/prof_shivajirao/resume.html