Pamba-Achankovil-Vaippar Link
Pamba-Achankovil-Vaippar link project consists of Punnamedu dam on PambaKalAr, AchankovilKalAr dam on AchankovilKalAr and Achankovil pumped storage dam on Achankovil River. The Punnamedu and AchankovilKalAr dams are interconnected by a tunnel of 8.0 km length. The water stored in Punnamedu reservoir will be diverted to AchankovilKalAr depending on the irrigation requirement and reservoir level at AchankovilKalAr dam. The water from AchankovilKalAr reservoir will be diverted through a 9 km tunnel to cross the Western Ghats. The main canal will take off from the tunnel exit and runs for a length of 50.68 km before reaching AlagarOdai, a tributary of Vaippar. The link canal will provide irrigation benefits to 91400 ha. Peaking power station of 500 MW installed capacity is located at the toe of AchankovilKalAr dam. Six mini hydropower plants with a cumulative installed capacity of 8.37 MW are located near inlet of inter connecting tunnel of Punnamedu and AchankovilKalAr reservoir, toe of AchankovilKalAr and Achankovil dam and at four canal drops on the main canal.
The peaking power plant comprises 5 units of 100 MW each. Three of the units are reversible type. 10 Mm3 of water released from AchankovilKalAr reservoir, for power generation during 6 hours peak load will be pumped back to AchankovilKalAr reservoir during the remaining period.TheAchankovil pumped storage scheme acts as a balancing reservoir for pumping the yield of the independent catchment of Achankovil river upto the dam site (excluding the catchment of AchankovilKalAr) to AchankovilKalAr reservoir. The project will require 2283 MU of energy to lift the water to AchankovilKalAr and 1095 MU and 19 MU of energy respectively will be generated during the peak hours and other periods.
The pumped storage scheme also provides economic benefits to the integrated grid by absorbing and utilizing the energy when not, otherwise needed to the system for pumping back and generating the power to supplement the system during peak load periods. The 10 Mm3 of water released from AchankovilKalAr reservoir for power generation during 6 hour peak load period throughout the year will be pumped back to AchankovilKalAr reservoir in 16 hour period. Since considerable off-peak surplus energy would be available when large nuclear and thermal stations are operated in the region at higher load factors in the grid, this idle energy can be utilised for pumping.
With the introduction of irrigation and increased agricultural activities employment opportunities would be created, general prosperity of the people of area will be improved. The command area of the proposed link canal includes some of the chronically drought prone areas of the country where even the drinking water is a scarce commodity.
The quantum of 634 Mm3 of water proposed to be diverted by this link amount to only about 20% of the surplus available in Pamba and Achankovil rivers. The provision of regulated releases of 150 Mm3 during lean season will improve the flow in the river during the lean periods and help combat salinity intrusion, pollution control etc.
The cost of project has been assessed as Rs. 1397.91 crores (1992-93) and is programmed for completion in a span of 8 years. The B.C. ratio works out to 1.008.
