Somasila-Grand Anicut Link

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Pennar (Somasila) – Palar - Cauvery (Grand Anicut) link forms a part of the scheme of transfer of the surplus waters of river Mahanadi and Godavari to the deficit basins of Krishna, Pennar, Cauvery and Vaigai. It is an important part of the various proposals for inter-basin water transfer under the Peninsular Rivers Development component of the National Perspective Plan. Pennar-Palar-Cauvery Link project envisages construction of a link canal from the existing Somasila reservoir across Pennar River in Andhra Pradesh to existing Grand Anicut across Cauvery River in Tamil Nadu.

The project comprises of the following components:

  • A head regulator on the right side of existing head regulator for Kandaleru Flood Flow Canal with a design discharge capacity of 603.33 cumecs.
  • A 529.190 km long link canal taking off from the above head regulator with FSL at 95.420 m and designed capacity of 603.33 cumecs.

Pennar (Somasila)-Palar-Cauvery (Grand Anicut) link project envisages diversion of 8565 Mm3 of water, from the existing Somasila dam across Pennar River in Nellore district of Andhra Pradesh State.The canal will run parallel to the existing Kandaleru Flood Flow Canal upto RD 10 km, Kandaleru – Poondi canal upto RD 80 km and then traverse a distance of 439.190 km before joining at Grand Anicut across Cauvery River in Thanjavur District of Tamil Nadu State.The link canal traverses through Nellore, Chittoor districts of Andhra Pradesh; Tiruvallur, Kancheepuram, Vellore, Tiruvannamalai, Villupuram, Cuddalore, Perambalur and Tiruchchirappalli districts of Tamil Nadu, passing through the river basins of Pennar; Streams between Pennar and Palar, Palar, Streams between Palar and Cauvery and Cauvery. The existing Somasila dam is proposed to be utilized as off take of canal for the intended diversion.

The link canal will provide irrigation to an area of 491200 ha in the Nellore and Chittoor districts of Andhra Pradesh; Tiruvallur, Kancheepuram, Vellore, Tiruvannamalai, Villupuram and Cuddalore districts of Tamil Nadu and Pondicherry (UT). Apart from irrigation, it is also proposed to provide water for future domestic and industrial water requirements of Chennai City, domestic requirements of the command area and towns located 20 km right side of the link canal with in a lift of less than 100 m. Additional domestic and industrial requirements, projected to 2050 AD, are estimated to be 605Mm3 and 500 Mm3 respectively. Transmission loss in the link canal is estimated to be 557 Mm3.

The link canal is designed as a lined canal with trapezoidal shape with rounded corners. The maximum carrying capacity of the canal is 603.33 cumec with corresponding cross section of 72.40 m of bed width and 6 m of full supply depth in the head reaches. The canal passes mostly through dry lands.

Pennar (Somasila) – Palar – Cauvery (Grand Anicut) Link Project does not involve construction of any new storage reservoirs. Also looking at the region through which the 529.190 km long link canal is traversing, the canal is not expected to lead to any adverse Environmental Impact. The link canal alignment does not cross any built up area and hence no R&R of displaced population is anticipated.

The link project on implementation would create the irrigation facilities to the farmers and tremendous potential for employment for the people of the area hence it would improve the economic conditions of the people of the region.Direct benefits per annum from the link project due to irrigation, domestic and industrial water supplies are estimated to be Rs. 1642 crore.

The capital cost of the link canal is estimated to be Rs. 6769 crore at 2003-04 price level. The apportioned annual cost of the project is Rs. 417 crore. The Benefit Cost Ratio works out to 3.93. The apportioned cost of water brought for this link project by the upper links is not added to the capital cost. The B.C. ratio may undergo a change if the cost of transferring surplus waters from the upstream link canals is also considered.

Source:National Water Development Agency (NWDA)

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