Not many years ago, river linking was a concept but it is becoming reality in the country. Discuss the advantages of river linking and its possible impact on the environment.

Advantages of river linking

• Flood moderation in surplus basins (parts of the Ganga-Brahmaputra and some monsoon-swollen peninsular rivers) if water is stored and diverted before it inundates plains.
• Drought proofing and extra irrigation in deficit regions such as Bundelkhand (the Ken-Betwa logic) and rainfed peninsular tracts.
• Navigation on more reliable channels, which can cut diesel trucking if inland waterways are actually maintained.
• Hydropower at dams and drops along transfer canals, adding peaking power to the grid.
• Urban and industrial supply for growing cities that have outrun local rivers and groundwater.
• Employment in construction and, later, in irrigated agriculture, which is the political case in dry districts.
• Intra-basin and smaller links can be less disruptive than a full Himalayan-to-peninsular grid; not every advantage needs the entire map built at once.

Possible impact on the environment

• Terrestrial ecology: canals and reservoirs submerge forests and wildlife corridors (Ken-Betwa has faced Panna tiger habitat concerns).
• Aquatic ecology: altered flow, temperature and silt change fisheries, dolphins and the pulse that floodplain agriculture needs.
• Delta and coast: less water and silt downstream can worsen salinity, mangrove stress and relative sea-level problems in already sinking deltas.
• Himalayan links add seismic, landslide and glacial-lake risk; climate change makes surplus and deficit non-stationary, so a link sized on old hydrology may fail.
• Displacement and command-area waterlogging or salinity if irrigation is heavy and drainage is weak.
• Interstate and transboundary harm: a link that is an advantage for one State can cut lean-season flow for another, or for Bangladesh on Himalayan rivers.
• Construction embodied carbon and quarry damage are large for a national grid of canals.
• Environmental impact assessment and wildlife clearances must therefore be basin-wide, not project-sliced, or the 'reality' of linking will export drought and extinction downstream.