The average annual rainfall water in India is 1,37,000 tmc, of which 66,000 tmc water flows into the rivers. Thanks to the Himalayas, the Ganges alone carries 18,000 tmc water in a year. Of this, after completing all the projects under construction, less than 4,000 tmc water from the Ganges could be stored for utilisation, according to the Integrated Hydrological Data Book 2015 of the Central Water Commission.
Being a classified river, we do not get finer details of the Ganges. Hence, it is safe to assume that at least half of the 18,000 tmc water of the Ganges alone goes to the Bay of Bengal in a year.
The current canal-irrigated area in India is less than six crore acres. However, India could add or convert nine crore to canal-cultivated irrigation utilising the surplus water in the Ganges alone.
There is an acute shortage of river water almost every year in Cauvery and Penna basins and most years in Krishna basin as well as in the entire upper Godavari and central Godavari basin in south India, where the capacity to utilise river water is far higher than availability. In 1972, Dr KL Raon, then irrigation minister, rightly mooted the interlinking of rivers by connecting the Ganga with Cauvery.
However, the proposal is facing challenges and only a few parts have been completed till date. The National Water Development Authority has completed water balance studies of 137 basins and sub-basins and 71 diversion points. It has identified 30 links — 16 under the peninsular component and 14 under Himalayan.
Studies have so far put emphasis on water flow by gravity. Hence, the links invariably serve the coastal or low-lying inland areas and is much less or absent in arid and semi-arid central and Deccan plateaus, where India faces severe drought, water deficit and high farmer suicides. It also ignores vast potential of the inland areas in Jharkhand, Chhattisgarh, Odisha and MP.
The basic principles behind suggesting the national river water grid from the Ganges to Cauvery are:
1. Lift from assured surplus water point of the river (tends to be after its main tributaries have joined and well before the river reaches the sea (eg: Around Begusarai area in Bihar)
2. Link water deficit areas through lift or gravity canals to the rivers or better to the already existing reservoirs on those rivers (Eg: Tilaiya, Bargi, Thanwar, Srisailam, Mettur reservoirs)
3. Utilise the contours along the inter-basin ridges for the canals to serve both basins to North, South, East and Westward flowing peninsular rivers (Ridge of Ganges – Damodar, Ganges–Mahanadi, Mahanadi–Narmada, Godavari, Mahanadi, Godavari–Krishna, Krishna–Penna)
4. Utilise the natural river flow and bed and make them as permanent water bodies as much as possible (Wainganga, Pranahita, Godavari through reverse pumping)
5. Leverage all big reservoirs in each basin and give preference to reservoirs on upstream than downstream as water filled in upstream can serve the basin downstream too. (Eg Srisailam can ensure Rayalaseema, not Nagarjunasagar or Pulichintala as proposed in ILR link 16 and 17)
6. Create enough number of balancing reservoirs to impound and stock water with lesser evaporation losses by choosing natural valley areas, if possible on the ridges of two basins as common reservoir can serve both basins through gravity (Eg, around Golgosumko in Jharkhand, Pandra)
7. Incorporate locks and clearance of bridges over the canals to support converting this into the national inland waterway for most part of the year
8. All States have their basin-wise assured quota of water supply while the remaining is kept under central control. Each year deficits and surplus vary from basin to basin. The NRWG can bridge the differences to ensure basic minimum water requirements in each basin, which can be secured for assured drinking water supply
9. Execute this as a national project by introducing water usage fee on the States so that they use it judiciously but do not have to incur capital cost. The Centre can use the funds for maintenance as well as re-invest it for extensions of the project
10. From 900 tmc up to 1,200 tmc could be easily utilised through stabilising large command areas and by adding new command areas for irrigation
The proposed national river water grid has more advantages with same or lesser cost and would make the links 16, 17, 20, 21, 22 redundant as this grid will achieve all the objectives set in these five links. (see map)
The growing Indian population will see the demand for water going up by at least 50% as compared with the current utilisation. And such a project takes at least 10 to 15 years for completion. The massive lift-and-link project on River Godavari is under execution by the Telangana government. However, the project would give incremental results from 2018 till may be 2022.
Lift irrigation is not viable. Irrigation projects take too long, inter-State agreements do not happen and a large amount of water is required for paddy.
Water is the best means available for governments to drive poverty out and generate productive workdays for various skilled and unskilled workforce. There is no better and easy option for the government to prevent farmer suicides than to ensure assured water supply for their crops without depending 100% on rainfed irrigation.
Just as the US and Europe offered fundamental water security to all its citizens in the 19th and 20th centuries and China in the 21st century, India has to act fast for ensuring its water security by lifting water and diverting it from surplus Ganges to all deficit regions.
(The author is a technocrat from Tokyo, Twitter @gandhi_pv)