flooding Dam

        Recently the Chief Minister of West Bengal  Mamata Banerjee has written a detailed letter to Prime Minister Narendra Modi regarding the man-made floods created in her state due to excessive  water discharge from Damodar Valley Corporation (DVC) Dams. In particular she has criticized the discharge of about 10 lakh acre-feet of water between September 30 and October 2 2021 which caused serious devastation  in lower Damodar region before the festival season.

She has reminded that she has not yet received a reply to her earlier letter sent on August 4 2021 in which she had “ highlighted the structural factors that give birth to grave man-made flood situation in southern Bengal, repeatedly, pitifully and tragically.”

Earlier the Bihar Chief Minister Nitish Kumar had raised questions about Farakka Barrage aggravating flood sitiuation in some parts of the state and elsewhere too.

These  statements of two Chief Ministers should be seen together with what has been reported from several other parts of the country regarding excessive dam water releases leading to very destructive floods and dams and barrages contributing to floods in other ways as well. Another interesting aspect is how the points made by the two Chief Ministers, although made in different contexts , turn out to be related to each other, a point to which this article will return.

A disturbing aspect of many flood situations in recent years has been that these were caused by sudden and heavy discharge of water from dams. The highly destructive floods in Surat in 2006, for example, were caused by heavy release of water from Ukai dam. Around the same time the  South Asia Network of Dams, Rivers and People reported,  “Mismanagement and negligent operations of the largest reservoirs on Tapi, Narmada, Krishna, Godavari, Mahi and Sabarmati rivers have caused man-made disasters in Gujarat, Maharshtra, Madhya Pradesh, Karnataka and Andhra Pradesh. The big dams that were expected to reduce the floods have actually been responsible for the flood disaster visiting these states now, the states that also happen to have the largest number of big dams.”

Looking at other such reports of recent decades we find that water releases from dams of the Damodar river system, the Bhakra-Beas system, Hirakund dam and several other dams have caused very destructive flash floods. Such floods are different from the gradual rise in river water seen in normal floods and the destructive capacity of such floods is much higher than normal floods.

Theoretically and on paper, dams with storage reservoirs are supposed to contribute significantly to flood-control but in practice, with deforestation in catchment areas, very high silting, poor management , distorted priorities and improper project appraisal this expected protective role instead turns destructive. Although officials point out that at times such heavy release  of water becomes unavoidable for dam safety, critics allege that frequently  due to the pressure to maximize hydropower, enough attention is not given to flood-control. As a result there is not enough capacity in the dam reservoir to absorb floods and very heavy discharges have to be made resulting in flash floods. Such situations are more likely to arise towards the end of the  monsoon season or an extended monsoon season when flood-control gets less attention.

In 1988 such an extremely  serious flood situation emerged in Punjab due to excessive discharge of water from Bhakra-Pong dams built on Sutlej river. Commenting on these floods which caused immensed damage including loss of lives, Prof. G. S. Dhillon, Dept. of Civil Engineering, Punjab Agriculture University wrote, “Bhakra and Pong, mighty dams that they are, still could not protect Punjab from flood; rather discharges from their overfilled reservoirs added to the problem … This has led the people to lose their faith in large dams operated for the purpose of power and irrigation mainly and people feel that the flood control aspect has been neglected by the authorities in charge of operation and maintenance of these dams. If that is not the case, how can flood storage space of the Bhakra dam above EI 1685 be converted into storage in the interest of irrigation and power. It is rumored that the authorities panicked and released the volume stored above EI 1685, they forgot the headworks downstream have limited capacity.”

On the other hand,  senior officials of the Bhakra-Beas Management Board (BBMB) stated that they had saved the dam under very adverse conditions. In his inter-action with newspersons the late Gen. B.N. Kumar, Chairman of the BBMB, made the following statements soon after the disaster –

“We all in Punjab and many others elsewhere were 0.03 inch away from one of the worst catastrophes in living memory during the last week of September when the Bhakra dam’s concrete structure registered a 0.99 inch tilt against its danger mark of 1.04 inches. We have saved the Bhakra dam as its survival was essential, else it would have been all over.

“We measure the tilt of the dam by a piano-wire – like pensulum, through a hole which runs from top to bottom of the dam. The tilt during these four days (Sept. 24 to Sept. 27 was between 0.95 inches to 0.99 inches against its designed non-seismic tilt of 1.03 inches. In fact Punjab and other parts were 0.04 inches away from disaster.”

Asked what would have happened if Bhakra dam had given away, Gen. Kumar closed his eyes and raised his hands saying – “It is unthinkable, and the very thought is horrifying – we would not be here to review the flood disaster.”

This clearly shows how big risks are faced at times in dam management and how these are related to water flows and discharges. Floods  cause immense harm and cannot be seperated from dam safety. Heavily silted dams face a more difficult situation. As Mamata Banerjee has written particularly in the context of Bengal in her recent letter, “ Unless the government of India addresses the basic underlying structural and managerial issues, both on a short term and a long term basis, the disasters will continue unmitigated in our lower riparian state.”

However the question is not just of excessive release of dam water. If we look at extremely destructive floods in Uttarakhand in recent times, these were aggravated greatly by construction of  dam projects in several ways such as obstructing the natural flow of river, making many areas more vulnrable with blasting work, careless disposal of vast debries and rubble in rivers and other ways. A major problem is that the dam projects leave mounds of muck and when floods carry the debries and boulders then their fury and capacity to destroy increases greatly. The linkage of floods to hydel projects including under construction ones has been well documented in a report prepared, at the directions of the Supreme Court, by a committee  chaired by Dr. Ravi Chopra.

Of course the biggest damage takes place in the case of dam collapse, such as the collapse of  Machu dam which proved so destructive for Morvi town in Gujarat.  There have been around 50 dam collapses during the last 65 years in India, including Kaddam, Chikahole, Dantwada, Aran, , Khadakwasla. Here again Uttarakhand ( as well some downstram areas of other states) is placed in the more vulnerable situation due to the construction of highly hazardous Tehri dam project constructed against expert advice on the Himalayan reach of the Ganga river . In this context again it was an officially constituted River Valley Projects  Appraisal Committee of the Ministry of Environment, which had warned of the most terrible consquences for the downstream thicklly populated cities like Rishikesh and Haridwar if something happens to this gignatic structure. At the same time this committee as well as other committees and experts have argued in detail about the extremely hazardous characteristics of this project and threats to its safety.

The Farakka Barrage Project on Ganga river in Bengal has also faced much criticism for aggravating floods, but in different contexts. The Chief Minister of Bihar Nitish Kumar has spoken more than once  regarding the  adverse impact of Farakka barrage on making Bihar more prone to floods. Others have added that this project has a similar impact on parts of W. Bengal too, particulrly Malda and Murshidabad.

Nitish Kumar has stated that the project by increasing the silt load in the Ganga river has made it difficult for flood waters to be cleared quickly. He has also gone  further and asked for decommissioning of this project once this need is confimed. This demand has also been supported by several activists and movements like the  Ganga Mukti Andolan voicing paticularly grievances of fisherfolk.

A former irrigation minister of W. Bengal Devavrata Bandyopadhyaya  said some years back that the people of Malda and Murshidabad are doomed by this project. He had said this in the context of increasing erosion of land and the increasing tendency of the river water to erode land as the river bed is clogged by too much silt.

Former Chief Engineer of W.Bengal Kapil Bhattacharya had strongly opposed the Farakka Project at planning stage. Instead of heeding his device he was victimized and lost his job. Later he emerged as a leader of the human rights movement and remained true to this role till he breathed his last.

Bangladesh of course has all along been opposed to the Farakka project due to the adverse impacts on water availability. Farakka Barrage has often strained relations of two friendly countries.

The messy story started much before Farakka Project with Damodar Valley Corporation (DVC) dams. These projects failed to take into account flood-tides and tide-silts. A lot of silt and sand accumulates in the lower reach of Hooghly river, the branch of the Ganga which moves towards W. Bengal ( the other branch which moves towards Bangladesh is called the Padma). This was  earlier flushed into the sea by the normal floods of Damodar and Rupnarayan rivers. But this natural process was disrupted by the DVC dams . The silt deposits accumulated, reducing the water carrying capacity of the river and causing destructive floods. The navigability of the Hooghly river was threatened, endangering the future of Calcutta Port.

It was to solve this problem that Farakka Project was pushed. Kapil Bhattacharya argued that the problems can be solved instead by using the irrigation water of DVC dams for flushing the Hooghly river . The irrigation loss can be made up by many water-conservation and small-scale irrigation projects whose total cost would be much less than the Farakka Project. But motivated by the big construction lobby the Farakka Project was promoted instead to take more water to the Hooghly. The Project was completed in 1975, more or less.

Bangladesh was soon complaining that after the diversion the lesser flow to the Padma river led to  sand accumulation in its lower reach which could even change the river flow and hence bring floods in new areas, while also causing water shortages in most other areas in the lean season. There were also reports of salt water intrusion in coastal areas and adverse impact on fisheries. Soon reports of very adverse impacts also started appearing from several parts of India, namely Bihar and W. Bengal, much along the lines of what had been predicted by Kapil Bhattacharya. This has proved to be a classic case of the effort being made to correct an original mistake proving to be even more costlier than the original mistake. This also shows how issues raised by Mamata and Nitish in the context of different projects are actually linked to each other.

What then is the way out? Mamata Banerjee has written in her recent letter to the PM, “ This annual problem requires immdiate short-term and long-term measures so that the sufferings of the  people  are mitigated and the national loss in terms of loss of life and property is avoided.” She has further urged, “ I request that the Government of India should get into some serious actions without further delay.”

What should such actions be, keeping into consideration the wider national and regional context? Clearly dam management should improve significantly so that flood protection objectives are never subordinated .or sacrificed in the quest for other attractive objectives like maximizing electricity generation. Siltation rates should be properly assessed and not underestimated as is often done. Catchments should be well-protected. Unfortunately all this is easier stated than achieved. The reality has been that of violations of all these suggested good practices. Ecological ruin of crucial catchment areas has if anything agravated further in recent times.

Overall much better and more detailed appraisal of dam projects is badly needed.. all the real hazards and problems should be propery accessed and instead of taking a simplistic approach, the longer-term impacts and chain impacts should be properly considered so that projects more likely to increase floods risk are avoided at the outset. This has become even more essential in times of climate change when possibilities of more torrential rain concentrated in shorter time spans has increased significantly.

Bharat Dogra is a journalist and author, is Honorary Convener, Campaign to Save Earth Now. His recent books include Planet in Peril and Man Over Machine.

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