What is the issue?

• Tamil Nadu recently launched its intra-State river linking project by building a canal from the Cauvery to the Vaigai and the Gundar, a part of the larger Godavari-Cauvery Link Project.
• The rationale for the plan causes concerns given the environmental and geographical features of the region developed over the years.

What does the project aim at?

• The Cauvery - Gundar link project forms part of the peninsular rivers’ development component of the National Perspective Plan.
• The latter envisages diversion of surplus flows of the Mahanadi basin and the Godavari basin to the water-short Krishna, Pennar, Cauvery, Vaigai and Gundar basins in the South.
• The Cauvery - Gundar link project seeks to divert surplus flows from the Cauvery to the water scarce southern parts of the State.
• This component will be carried out in three phases:
  1. First phase – linking Cauvery to the South Vellar river (118.45 km)
  2. Second phase - linking the South Vellar and Vaigai rivers (110 km)
  3. Third phase - linking the Vaigai with the Gundar river (34.04 km)
• The first significant step towards the linking was made with the commissioning of the barrage across Cauvery at Mayanur in Karur district in 2014.
• The barrage will form the head of the new link canal.
• The link canal will carry the surplus waters from the Cauvery to the South Vellar, the Vaigai river and finally the Gundar.
• The canal will have a capacity to carry about 6,000 cusecs of water.

What is the government’s rationale?

• The Cauvery is perceived to carry surplus water.
• This is mixing into the Sea unused, when the water demand for agricultural use is evident year after year.
• So, the idea is to divert the surplus water through a canal, so as to irrigate farm lands.
• The canal, of nearly 250 km, travelling North-South, will carry 6,000 cusecs of water from Kattalai barrage in the north end, to the Gundar river in the South.

What are the concerns with this approach?

• The idea of surplus or deficit in terms of a river seems essentially flawed.
• It all depends on the amount of water being used and for what.
• The excess water flowing across the banks ought to be identified as flood; it is not surplus indeed.
• In that case, floods are to be seen neither as wastage of water nor as surplus and so to be commercialised.
• This is because floods do play a key role in a riverine ecosystem and the associated geographical features.

Why are floods significant?

• The present day Cauvery delta region is largely a result of the deposits and sedimentation formed with floods in Cauvery river over generations.
• All these resulted from the free flow of water along the entire course of the river from its various tributaries, canals and up to the streams and rivulets.
• Excavations in the Cauvery banks and the region around, if done, would reveal this fact.
• Floods thus play a key role in delta formation.
• Moreover, the flooding at intervals and free flow of water along the river channel help preserve the biodiversity of the region, especially fishes.
• Related article: Kaziranga and Brahmaputra Floods

What impact will the plan have over the deltas?

• The Cauvery River has already in place an old delta and a new delta.
• The former one was formed naturally by Cauvery and its tributary Vennar.
• The latter took shape as a result of constructing the Kallanai Dam (Grand Anicut) in the 1930s.
• Now, the inter-state river link project is expected to make way for a new, third delta for the Cauvery.
• The link river would notably pass in the north-south direction.
• So, a possible delta formation over the course of time could interrupt the natural course of Cauvery and the natural geo-features in the region around.
• This may not happen any soon but the idea of viewing floods as surplus water and commercialising it are disturbing trends to environment protection and conservation.

Source: The Hindu