Mullaperiyar Dam,then and now
A little history
Theckady is the border that links Kerala with Tamilnadu.A few decades back a view from the present damsite eastwards would have shown us the sight of a limitless stretch of barren land wearing a desertlike look.Kambum,Theni etc were clearly seen in this way.Behind us we could see the dense forests in the Kerala region.But decades of hardwork by the people there together with the perennial supply of water from the Mullaperiyar dam converted this vast stretch of land into a greenery which brought a fortune to the toiling farmers there and supported the daily life of Keralites with regular supply of vegetables ,fruits pulses ,milk and flowers `
The unique idea of harnessing the Westward flowing waters of the Periyar river and diverting it to the Eastward flowing Vaigai river was first explored by PM Pillai ,a minister of the then Ramnadu king `,Muthuramalinga Sethupathy. He dropped the scheme as it was found to be an expensive project.Later during the rule by the British East India Company experts from the Madras Engineers,specialists in construction work took up the project but they too gave up the idea as it required deep mountain drilling in excess of 100 Ft.
An earth dam was conceived in 1850 by the British authorities,but following the demand of exhorbitant rates by the labour citing unhealthy living conditions ,it was put in the cold storage again.
The entire Southern region came under severe famine during the period 1876-’77 This made the authorities to reexamine the issue on a warfooting.In 1882 a masonry dam was proposed to be constructed at the confluence of the Mullai and Periyar rivers ,hence the name Mullaperiyar.It was Major John Pennycuick from the Madras Engineers who revised the project and got the approval for the construction of the dam in 1884.
Sructure
The Mullaperiyar dam is a masonry gravity dam.Gravity dams use their weight and the force of gravity to support the reservoir and remain stable.It is located at an altitude of 881 metres (2890 Ft )above sealevel on the cardamom hills of the WesternGhats in Theckady.The construction was during the period 1887 - 1895.The dam has a height of 53.6M(176 Ft )and a length of 365.7 M (1200 Ft ) The wall on the reservoir side of the dam is almost vertical and the supporting part on the Tamilnadu side is slanting outwards from top to bottom.The crest of the dam (top ) is 3.6 M wide (12 Ft ) and the base is 42.2 M (138 Ft ) wide .The huge structure is built with limestone and Surky (a mixture of crushed bricks,sugar and quicklime.)
Lime gets leached by the dam water and gets gradually dissolved in it.Also at lower temperatures of the reservoir,the dissolution process gets accelerated.This affects the masonry of the dam ,and in case of floods or earthquake,the dam may collapse easily.
The main dam has a spillway on it’s left and an auxiliary dam ( baby dam ) on it’s right, along with an earthdam formed out of the mud removed during the formation of the reservoir.The auxiliary dam has a length of 104 M (340 Ft ) . The dam can hold 443 million M3 ( 360000 Acre Ft )of water.Of this 300 million M3 (242500 Acre Ft) is the active storage.The total cost for the construction of the dam is estimated to be Rs I Crore .
About 483 people have lost their lives due to Malaria and other reasons during the construction of the dam.
On 29th October 1886 a lease agreement ,valid for 999 years ,was registered between the King of Thiruvithamcore ,Sri Visakhom Thirunal and The British Secretary of State for Tamilnadu, for the Periyar Irrigation Works .The lease agreement was signed by V Ram Iyengar,Dewan of Thiruvithamcore and J C Hannington,Madras State Secretary. The dam and the river are owned by and located in Kerala.But the dam proper is controlled and operated by TamilNadu under the provisions laid down in the period lease. The dam created the Theckady reservoir.
Water from the dam is diverted eastwards through a tunnel into the Vaigai river to augment its small flow from upstream. Later the Vaigai dam was also constructed by Tamilnadu for irrigating large parts of Madurai district.In 1956 Tamilnadu Govt.constructed the Periyar Power Station in the Lower periyar region.For this water from the Periyar lake is diverted through the watershed cutting and a subterranean tunnel (570 FT long )to the Forebaydam near Kumily(Errachypalam in Tamilnadu ). From the Forebaydam hydelpipelines carry the water to the Periyar power station in LowerPeriyar (in Tamilnadu )The capacity of this HE project is 175MW.
From the Periyar powerstation the water is let out into the Vairavanar and Suruliyar rivers and from there to the Vaigai dam. Water from the Mullaperiyar dam helps in maintaining Thrice year cropping in the Madurai, Sivaganga and Ramnadu districts of Tamilnadu.
Morby dam disaster 1979
The height of the waterlevel in the Mullaperiyar dam was maintained at 142.2 Ft for a long time.This enabled Tamilnadu to steadily increase the irrigated areas over a period of time.
On 11th August 1979,the Morbi dam built across the Machchu river in Gujarat was washed off in the heavy rains that leashed across that state.Morbi was one of the most prosperous regions in the Western India for centuries .The dam was expected to further the fortunes of the region.That hope was shattered by the collapse of the newly built dam.More than 10,000 lost their lives.
The Morbi disaster sent shockwaves to the South also.Doubts were expressed by the Kerala govt regarding the strength of the Mullaperiyar dam as several leaks and cracks were visible in the dam already.The Kerala government asked CESS (Centre for Earth Science Studies )to study the situation and submit a report.The Central Water Commission ( CWC ) also inspected the site .On the orders of the commission the TN government lowered the water level from the existing 142.2 Ft to 136 Ft. Besides the Tamilnadu government also took some measures to strengthen the dam.
Thereafter both Kerala and Tamilnadu have been lobbying for their own cases.Tamilnadu wanted to confirm the adequacy in the strength of the dam and hence for restoration of the water level to 142.2 Ft or even more.It claims that the state had a loss of nearly Rs 40,000 Crores during the period 1979-2005, due to the 3 to 2 reduction per year in the number of crops harvested.
The several earthquakes which caused damages to lives and properties In the neighbouring regions (Idukki and Kottayam districts ) have sent shockwaves across the state forcing people to take to streets and pleading for a new dam to be built there at the earliest.As an immediate precaution they demand the water levels be lowered to 120 Ft.The present dam has been included In the ‘Endangered Scheduled dam ‘by the Kerala Irrigation and Water Conservation ( Amendment )Act 2006.
Solution - VICTORIA DAM MODEL 1891
The only lasting solution to this delicate problem is the construction of a new dam in the upstream river. Wiser opinion s from matured brains from both the states should be able to lead to a lasting solution to this vexed problem which can be easily solved once wisdom and pragmatism dawn on the leaders in both the states.
Here it may be good to know about the way in which a dam of the same age has been replaced by a new one .The ( Old )Victoria dam was constructed in Perth in Ausralia in 1891.(i.e.before the discovery of Portland cement ).Water from the dam was used for irrigation in large areas.It had 2 spillways.In 1939 one of these spillways was closed and the other expanded.But gradually water leaking through the dam wall leached the lime from the concrete,thus weakening the structure.Efforts to reduce the leaking were made in 1912,1939 and in 1966 besides regular maintenance.The upstream side of the dam wall was covered with reinforced concret to reduce further leakage.However a 1988 review of the dam’s design concluded that it lacked sufficient safety margins in the event of floods or earthquakes and it’s concrete had degraded to such a level that it could not be repaired and needed replacement.
The dicision to replace the old VICTORIA Dam was taken in 1989.Use of the old dam for watersupply ended on 3rd April 1990 and the construction of the new dam started on 23rd August1990.The newdam was constructed in less than a year after the excavation started.The dam (NEW VICTORIA DAM ))was officially opened on 22nd November 1990.
Ph 0484 2522662 Mob 9847093640 Prof.V S Haiharan
(Retd.Professor,Sree Sankara College,Kalady)
Email; prof.vshariharan@gmail.com 7/227,Vidya Bhavan
Perumbavoor PO
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