Linking rivers and large scale irrigation projects in the erstwhile Soviet Union resulted in a reduced flow into the Caspian Sea. The resulting disaster included a retreating shoreline, so that ports were several kilometers from the water, increased salinity, etc. Are there any other cases of river linking and its results? India is probably going in for this and it might be useful to know a bit more about the ecological, economic and practical impacts of lavish engineering schemes.
Yes, the Aral Sea is the example I was thinking of, but the Caspian has suffered a lot too, from dams on the Volga and other rivers... I see now that the shoreline of the Aral Sea has retreated by 50 to 100 km!
Dear Peter,
Can you be more specific in your findings.When a river is dammed,it results in a negative estuary & if there is a basin holding seawater during prolonged low tide,only then it results in increase in salinity,not otherwise.I don't understand as to how ports can result in their being several kilometers from its shore line. The only explanation could be heavy deposition of silt & clay at the mouth & in absence of river flow,probably the vessels would not be able to access ports located quite in the upper reaches of the mouth of the river. Probably they are not located right on the coast line.
Regarding interlinking of Indian rivers,waters of river Narmada through various canal systems has been linked with the Sabarmati river & currently is has become perennial. Though the plan is to supply Narmada river water to all arid districts in Saurashtra & Kutch,it has resulted in availability of water in these places,has raised the ground water level & has prevented ingress of salinity in coastal agricultural fields.
I still doubt the concept of linking rivers, the idea at present seems to be very innovative or beneficial, as we are simply transporting the surplus water of one perennial river to the rivers with low or nearly no flows, but who knows what may be the scenario after 50 or say 100 yrs from now, there might be the case that parent river itself start to face water scare condition then the whole system will be a failure....
Regarding interlinking of indian rivers @Trivedi sir has pointed out all the projects. These projects proved to be beneficial for short span of 5-10 yrs . As people take water from the canals or river water and with no discharge of groundwater then subsequently water table of that area will starts rising and ultimately comes to the surface leading to water logging and salinity. Sometimes it may also contain toxic elements such as As, F, B depends on the geological formation which leads to health problems.
As for all land and water management works there is no straightforward answer. Water needs are increasingly growing, from the roman Aqueduct to provide water to Carthage to large dams for linking rivers, mankind seeks to capture the available water resource and the most visible one of the lakes and rivers. Impact studies, fair share of the resource between users and environmental respect need to be taken in account in the decision to build a dam and especially to manage
Dr. Albergel introduced the key point here. Flow diversions and augmentations of any type are a sensitive balance between environmental needs and increasing societal demand. Large changes in the natural flow regime (whether it be the magnitude, timing, frequency, duration, or rate of change of flow) in any river has potential to impact aquatic and riparian biota by interrupting their life history and environmental queues including water temperature. Organisms have evolve within a particular range of variability. This is a challenge here in Colorado, USA with trans-basin diversions that divert a portion of flow from the western side of the continental divide, such as the Grand Ditch, to the east to supply agriculture and municipalities. This greatly impacts stream ecosystems.
Similarly the sediment regime, channel form, and landscape features including deltas, shorelines, and estuaries have all formed under given conditions for a given river. Interrupting those conditions through channelization of rivers, dams, diversions, and flow augmentations disrupts not only the flow regime, but also the natural sediment regime. Channelization and other human impacts are greatly impacting the Mississippi River delta in the Gulf of Mexico, USA in this way, encouraging shoreline retreat in some areas, while promoting aggradation and shoreline advancement in others.
Such changes happen naturally and the environment adapts, sometimes at the expense of ecosystems. Your question appears to be concerned primarily with whether society can adapt to the changes we have induced. Another aspect of this, as Bhumika mentioned, is groundwater. Moving water from one basin to another may impact groundwater recharge, potentially raising groundwater levels in one basin and lowering them in another.
Again, there is no clear answer, but linking rivers certainly may have a significant impact on the natural water and sediment regime, particularly when you are dealing with large rivers.
When a river is dammed, surely it will affect ecology, environment and in longer time climate of the region as we have seen in Aral sea in the past and currently in Urmia Lake, northwest of Iran. The blockage of the rivers feeding these lakes resulted in drying up of them as the rivers water was the only source of water chargers, therefore day by day the evaporation and excess pumping waters from wells for agriculture and irrigation led to increase in salinity and finally resulted in drying the lakes. In case of river linking, I think if the water is used for irrigation without effecting the lakes water level, will increase ground water levels and these high ground water levels themselves will supply water to adjacent lakes in turn and will protect basin subsidence too.
Thank you all very much for your inputs. i gather that the idea of linking rivers is restricted to the erstwhile USSR, where it proved disastrous in the long term, and now India. The reasons for linking the rivers are different; in the case of India, the rivers flow into the Arabian Sea or Bay of Bengal, so there is little fear of them drying as in the case of the Aral Sea.
However, the fundamental reason for doing so in India is tenuous, to say the least. i agree with Chandravan Trivedi that the Narmada and Sabarmati have been linked and the Sabarmati has 'become perennial'. Was this the correct way to achieve it?
When the trouble has been caused by an unmanaged or, at best, mismanaged landscape, is the answer to apply the equivalent of 'robbing from the rich to give to the poor'? I do not believe this is the way to mitigate the problem, rather it will be exacerbated in the long term.
Sabarmati river has its origin from southern Rajasthan state & is flowing through north Gujarat along Ahmedabad city & emptying its waters in Gulf of Khambhat. Dharoi dam had been put in place for providing irrigation waters to farmers down stream.If the demand & supply mismatches,naturally the authorities will try to find a solution to the problem.
On the other hand,waters of Narmada river was dammed & its waters are used by the 3 neighboring states.To mitigate the demand of water,canals were made to facilitate reach of Narmada waters to far flung rural areas of Gujarat state. In the process,extra waters were also made to flow through the Sabarmati river, so that the waters can be used by both the rural & urban communities.
So here,there is no question of "robing the rich to pay the poor".If the excess waters of Narmada river were not used in this way,it would have gone waste into the Arabian sea.
Chandravadan, 'excess water' is a subjective term. Usually the judgement for this is left to people with engineering backgrounds, rather than backgrounds in landscape management. That, unfortunately, is the root of the problem.
My Dear Peter Smetacek; In my country in India the idea of linking rivers is still continue the hot one for political circles and also for scientific community to manage surface water and made it available for irrigation in agriculture. Thanks
My dear Sarwan Kumar, I am aware that the idea of linking rivers 'is still continue the hot one" in our country, India. It is unfortunate that engineering skills are being applied to life support systems.
However, I asked the question to ascertain whether this ham handed approach has currency anywhere else in the world or not and from the answers above, it is evident that planners in other countries learnt lessons from the Aral experience that our planners did not. The only thing left to ascertain now is whether our planners are aware of the Aral experience and, if so, why we are being led into what will probably turn out to be an expensive ecological disaster at a time when fresh water resources are among the biggest challenges facing our country.
Is it only incompetence or is there some anti-national interest involved?
Definitely, it could be a costly ecological disaster. We would be miserably failed in maintain one of the important natural resources of the country. Lots of hue and cry made citing both –ve and +ve impacts of Inter-Linking of Rivers (ILR). The reports and discussion on the –ve impacts outweigh +ve impacts. But, the planners pushing hard to materialise the ecological disaster very fast in every means. It is the inherent problems associated with ILR makes the story delayed and makes us happy for some times. Anyway the planners need to heed to the outcry of ecologists, environmentalists and fisheries professionals as they definitely better understand the importance and complexity of ecosystems, and the plight of their management.
The national disaster should not be decided by few individuals, who have limited appreciation for ecosystems and ecological services, on which the whole world revolves.
It has now become a subject of national interest and need to bring the question for nationwide voting. If majority citizens vote for ILR, then we ought to abide by and phase through disasters. God only can save then. Let us be prepared for the eventuality.
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