Cauvery(Kattalai)-Vaigai-Gundar Link
Cauvery (Kattalai)-Vaigai-Gundar Link which forms a part of the scheme of transfer of surplus river water of Mahanadi and Godavari rivers to the deficit basins of Krishna, Pennar, Cauvery and Vaigai, is an important part of the various inter-basin water transfer proposals envisages under the Peninsular Rivers Development component of the National Perspective Plan. Cauvery – Vaigai – Gundar link project envisages diversion of 2252 Mm3 of water, from Kattalai barrage proposed by NWDA at a location downstream of the existing Kattalai bed regulator across Cauvery River.
The proposed link project comprises of the following components:
- A barrage at Kattalai across the Cauvery River with pond level 101.20 m
- A head regulator on the flank of the extreme right bank with a design discharge capacity of 180.30 cumecs.
- A 255.60 km long link canal taking off from the proposed head regulator with FSL at 100.75 m and designed capacity of 180.30 cumecs.
- It is envisaged that this link canal will provide en route irrigation to a culturable command area of 337717 ha utilising 1952.30 Mm3 of water besides providing 185 Mm3 of water for meeting domestic and industrial requirements.
The canal will run parallel and adjacent to the existing New Kattalai High Level Canal upto RD 36 km and then traverse a distance of 219.60 km before joining Gundar River. The link canal traverses through Karur, Tiruchchirappalli, Pudukkottai, Sivaganga, Ramanathapuram and Virudhunagar districts of Tamil Nadu passing through the river basins of Tirumanimuttar, Ponnanaiar (both sub-basins of Cauvery basin), area covered by the Streams between Cauvery and Vaigai, Vaigai basin and area covered by the Streams between Vaigai and Vaippar. A new barrage at Kattalai is proposed to be utilized as off take of canal for the intended diversion.
The link canal will provide irrigation to an area of 337717 ha in the districts of Karur, Tiruchchirappalli, Pudukkottai, Sivaganga, Ramanathapuram, Virudhunagar and Thoothukudi of Tamil Nadu state. The intensity of irrigation is proposed to be 100%. A cropping pattern was devised by NWDA appropriate to the command area. The irrigation water requirement is estimated to be 1952.3 Mm3.
Apart from irrigation, it is also proposed to provide for future domestic and industrial water requirements in the command area. Additional domestic and industrial requirements, projected to 2050 AD, are estimated to be 62 Mm3 and 123 Mm3 respectively. Transmission losses in the link canal are estimated to be 114.7 Mm3.
Cauvery – Vaigai – Gundar link project does not involve construction of any large dam but involves only construction of a diversion structure. Also looking at the region through which the 255.60 km long canal is traversing, neither the construction of diversion structure nor the link canal is 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 lot of employment opportunities for local population during construction and maintenance phase as such the economic conditions of the people in the region will improve. The link canal is designed as a lined canal with trapezoidal shape with rounded corners. The maximum carrying capacity of the canal is 180.30 cumec with corresponding cross section of 20.40 m of bed width and 5 m of full supply depth in the head reaches. The canal passes mostly through agricultural fields.
Direct benefits per annum from the link project due to irrigation, domestic and industrial water supplies are estimated to be Rs. 940 crores. The capital cost of the link canal is estimated to be Rs. 2673 crores at 2003-04 price level. The annual cost of the project is Rs. 299 crores. The Benefit Cost Ratio works out to 3.14. 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.
