The Hindu 04.01.2011
Water projects - the pride of Coimbatore
The linking of eight rivers through tunnels and storing the water in seven reservoirs at various stages under PAP constitute an engineering marvel of the Kongu region
A full Pilloor dam with the intake well, which supplies drinking water to Coimbatore, in the foreground. (Right) Siruvani dam which is the main source of drinking water to Coimbatore city. — Photos: K. Ananthan
At a time when Coimbatore Vizha highlights the rich natural resources and biodiversity of Coimbatore, it is compelling to touch upon the famous water supply and irrigation systems in this region.
The linking of eight rivers through nearly 30 km of tunnels and storing the water in seven reservoirs at various stages under the Parambikulam – Aliyar Project (PAP) constitute an engineering marvel of the Kongu region.
The west flowing rivers in the Western Ghats that drain into the Arabian Sea form the PAP project.
The scheme takes care of the irrigation needs of nearly four lakh acres in four zones of the ayacut and they get water once in two years on a rotation basis.
Two-thirds of the beneficiary areas are in the new Tirupur district (earlier part of Coimbatore district) and one-third in the present Coimbatore district helping them retain their agrarian identity.
In post-Independent India, the farmers mooted the scheme for bringing in an irrigation scheme. The proposal made in 1958 started taking shape in 1960 and the final stage i.e., the Lower Nirar was completed in 1982.
Water sharing
The sharing of water from PAP is governed by an inter-State river water sharing agreement signed in 1970 with retrospective effect from 1958.
The agreement was that Tamil Nadu would get 30.5 tmcft (thousand million cubic feet) and Kerala 19.55 tmcft.
The total realisation at Thirumurthi Dam as on date stands at 22 tmcft owing to rainfall deficiency, percolation and seepage loss because of the damages suffered by the contour canal over a period of time.
The State has recently announced a scheme for repair of the contour canal at a cost of Rs.184.5 crore.
The rivers linked are Nirar, Anaimalaiaru, Sholayar, Parambikulam, Thoonakadavu, Peruvaripallam, Aliyar and Palar.
Of them, the last two rivers are in the plains while the rest are in the ghat section. Except Palar and Anaimalaiaru, there are dams across almost all the rivers.
The water is taken to Thirumurthi reservoir through a number of tunnels totally measuring 30 km while the contour canal from Sircarpathy power house to Thirumurthi measuring 49.3 km alone has a 9 km tunnel.
As far as pending works in the PAP scheme as per the inter-State agreement are concerned, Tamil Nadu is waiting for construction of the Anaimalaiaru dam and has been demanding construction of Niraru-Nallaru dam. Kerala has to complete the Idamalayar dam as per the agreement.
One main requirement for industrial growth is power and Coimbatore is a beneficiary of two major power projects.
Pykara and Kundah are two hydro projects in this region that generate 833 MW jointly.
Coimbatore is the main load centre for these two projects.
According to an official, the main water source for Pykara is Mukurthi and it is Upper Bhavani and nearby water sources for the Kundah.
Kundah and Pykara projects have six power houses each. The power generated from these two projects mostly caters to the morning and evening peak hour demands.
The Pykara project took off in 1932, facilitating industrial growth in Coimbatore. The Kundah project was inaugurated in the 1960s, according to the official.
For any outsider, getting to learn about Coimbatore will not exclude its landmark water supply projects, especially the Siruvani scheme that began providing water to Coimbatore in 1920. The dam construction began in 1977 and was completed in 1984.
Then began the drawal of 101 million litres of water a day following an agreement with Kerala (the dam is located in that State).
“The sweet Siruvani water” is what every brochure or promotional article on Coimbatore will contain, when its distinct features are being listed.
Decades ago, the perseverance of one of the architects of Coimbatore – C.S. Rathinasabapathy Mudaliar – led to implementation of the scheme.
Mudaliar led a team of experts and members of the Coimbatore municipality deep into the breathtaking Siruvani forests and identified the spot where a project could be implemented to provide drinking water to the municipality.
Siruvani water now flows to the city just by gravity over a distance of more than 30 km and this speaks volumes of how the scheme was conceived in such a way that expenses on power consumption for pumping the water could be avoided. The terrain too supported this initiative.
The other landmark is the Pilloor scheme. If the Siruvani project is all about Nature reaching out to the community through the gradient, the Pilloor scheme, implemented in the early nineties, is an engineering marvel.
Water from the Pilloor Dam reaches the city through a tunnel dug through a mountain. The scheme supplemented the quantum supplied from the Siruvani Dam.
Officials of the Tamil Nadu Water Supply and Drainage Board say the Pilloor project had been implemented with a lot of forethought. Provision for a second phase scheme had been made even when the first one had been executed.
This is why the Corporation is able to lay an additional line through the tunnel now to implement the second phase.
(With inputs from V.S. Palaniappan, M. Soundariya Preetha and K.V. Prasad)
