Ingenuity has been the hallmark of the human race. From Roaming hunters to cave dwellers and then from caves to agrarian societies occupying sky-scrapers has been the achievement of the race through the ages. In a race for development the humans have not spared even the nature. Geography has been frequently redrawn in the name of mining, construction of dams, tunnels or even large scale massive buildings on the mountain slopes.
In order to divert excess water from rivers to deficit areas the river linking has been carried out by some countries. Taking cues from them without in-depth studies the concept is being campaigned actively. Technically river linking will solve the water problem sensu stricto. Alas unlike pipes carrying water the rivers are not mere conduits of water. They are part of an ecosystem too. They have a certain hydrodynamics which is linked to factors like rising Himalayas and rates of erosion. We are perhaps in a great hurry to implement the concept!
The issue is debatable, because across the table it is possible to highlight the benefits or losses from such a project.
One lesser known aspect of perils of post-river linking is the salinisation and alkalinisation of large tracts of cultivable soil.
Canals are one of the cheapest modes of transfer of water from one river to another. Canal irrigation in our country is age-old. The adverse impacts of which are now becoming clearer. In the light of which the advantages of inter-linking of rivers appear to be more of disadvantage. It is a poser for the technocrats of the country whether they have analyzed and thought of the possible consequences prior to selling out this grandiose idea to the masses?
The country's population has soared from nearly 360 million at the time of Independence to more than one billion at present. The quantum jump in the population has increased the demand for food. Naturally intensive irrigation methods are required to augment the agriculture.
Irrigation was in vogue even in the historical past. The Grand Anicut is one of the engineering marvels of the 2nd Century AD. Till the beginning of 19th Century it was irrigating 0.24 million hectares (m ha). In the alluvial plains of the country canals were found to be the cheapest alternative of carrying water down the gravity over long distances. The western and the Eastern Yamuna canals are two classic examples of the 14th and 18th Centuries respectively. The drought and famines during the second half of 19th Century gave impetus to digging more canals.
Major canals like Indira Gandhi Nahar Pariyojna (IGNP-I and II) in Rajasthan, Sharda Sahayak in U.P., Tungabhadra in A.P. and Karnataka, Hirakud in Orissa, Mahi-Kadana in Gujarat, Kosi and Gandak Canals in Bihar etc came up.
The irrigated area of the country in 1950-51(beginning of first five year plan) was only 22.50 m ha. By 1999 it had crossed 85 m ha. No doubt there was a significant increase in the food production too.
The canal irrigation method has its own perils. We read with pride in the newspaper that such and such irrigation project has been completed and so many lakh hectare areas would be irrigated from the canals. Once the canal passes through an area the benefiting farmer is supposed to dig a channel between the public canal and his own land. He finds this cumbersome. Consequently several kilometers of channeled water have no takers. Most of the time the tail end of the canal does not get water and the farmers there always crib. No doubt the system is one of the cheapest modes of water transfer, but the transmission losses including the loss due to evaporation are tremendous, that is why the tail end goes dry. The slow moving water in the canal seeps down the depths of sub surface and also oozes out from the 'kutcha' embankments. Net result is development of 'sick' soils, water logging and soil alkalization along the lengths of canals.
Like water we take soil also for granted. The soil is almost a living ecosystem. Very few of us realize that the molecules of water held by the humus in the soil create almost a 'mini-atmosphere' for the living bacteria at the ground level. A healthy soil is fertile because of a balanced proportion of living bacteria, dead leaves and organisms. Over irrigation and poor drainage makes the soil 'sick'. The subsurface and the soils are rich in various salts. Due to capillary action colloids and salts travel from sub-surface to the top. It is amazing that presence of mere 0.2% of Sodium Chloride renders the soil infertile. Once such salts accumulate on the surface the 'sickness' of the soil travels fast and vast tracts are rendered useless.
The canal irrigation has turned almost 33% of soils 'sick' in their respective command areas. IGNP is one of the classic examples of the recent engineering marvels. IGNP is the largest canal system in the world with a canal command area (CCA) of 1.537 m ha. The canal system ushered a green phase in the dry areas of northwestern Rajasthan. Some villages like Baropal and Kalalon Ki Dhani became prosperous once the canal water gushed through them. However, within merely two decades these have been reduced to abject poverty due to water logging and salinity.
A report by the Central Ground water Board (CGWB) states that, as many as 30 villages of the upper reaches of the IGNP canal have become completely waterlogged with thousands of families rendered destitute.
IGNP was just an example. The scenario is same in Sharda Sahayak Pariyojana in U.P.; Tungbhadra Project in A.P. and Karnataka; Ghat Prabha in Karnataka, Mahi-Kadana in Gujarat. The list is endless. Due to clayey soils Karnataka is one of the worst victims of alkali and salt affected fields along the canals. The total area thus affected in the state is a whopping 204600 hectares.
The impact of large-scale diversion of water is not only limited to our Country. Aral Sea in Soviet Union, the fourth largest fresh water body in the world was reduced to 38,000 sq. km from the original area of 66,000 sq. km after a canal system was developed out of it from 1960s. It was thriving center for fisheries, due diversion of water, salinity of the lake increased in leaps and bounds the commercial fishery of about 40,000 tonnes per annum was reduced to zero. Increased salinity of the soil has made the agriculture impossible. As per a World Bank report the large-scale water transfer has created an ecological and human disaster. However, recent reports inform that reclamation of aquatic fauna has started in the Aral Sea, thanks to massive efforts by the people.
One might think what will happen to the lands turned fallow due to canal irrigation in our country. Well technologically it is feasible to puncture a large number of tube-wells to lower the water table and use canal and ground water in conjunction. For IGNP alone the CGWB has recommended drilling of 10023 tube-wells at an estimated cost of 72.17 Crores. The financial viability of such a project becomes doubtful when applied to the entire 'sick belt' of our agricultural fields. More tube wells would mean more power, who will bear the cost? The other alternative is to line the entire canal system so that no water leaks from them. In addition a drainage system will have to be developed in the cultivated areas to drain out excess water. Undoing the damage will naturally involve huge amount of funds. Perhaps that is the only way left to reclaim the soils rendered infertile!
Compared to vast area of our Country canal irrigated area is only a miniscule. In case the large river systems are inter-linked through canals soils in much larger areas would turn 'sick'. When it comes to construction projects, as a developing nation we always think 'big'. Instead of rendering few thousand people destitute to make the living of a few million we could introduce water management at macro and micro-levels.
Statistics show that 4000 billion cubic meters of rainfall in our country occurs in 8760 hours annually. Out of this a major chunk of rain falls within a span of just 100 hours. These 100 hours become crucial for Rainwater harvesting. It is believed that rain captured during these hours can last for the whole year for a parched village. Thus rainwater harvesting needs to be made a reality from sloganeering. The water bodies like lakes in the rural India need to be revitalized and cleaned for improved storage and development of fisheries. There are innumerable examples of lakes having been successfull as water storage devices.
Despite the information about the adverse impacts of mass water transport from other countries the river linking project was 'conceived'. It is well known that world over such massive projects have brought affluence to few and poverty to the masses.
As the story goes once a King got the power to turn everything that he touched to gold. Alas the King touched his own daughter one day!
Perhaps our government is waiting for the Midas touch!