November 19, 2017

The myth of the benign superdam

Are large dams inevitably destructive? Some critics have argued that if stringent conditions are laid down before a dam is authorised, the devastation of the past decades could be avoided. But a careful consideration of the suggested conditions shows that few, if any, dams could pass the test.

Co-written with Nicholas Hildyard. Published in The Ecologist Vol. 14 No. 5-6, June-July 1984.

Can there be satisfactory large scale water development schemes? On the basis of the empirical evidence, the answer to that question is a resounding “No”. Yet it is still assumed, implicitly at least, by even the most active and outspoken critics of large dams that if the site is geologically and ecologically appropriate and if sufficient precautions are taken, it is still possible to put up large water development schemes with relative impunity.

Four such critics are: Brent Blackwelder of the Washington-based Environmental Policy Institute; Philip Williams, a hydrologist and principal of Philip Williams and Associates, San Francisco; Barbara Bramble of the National Wildlife Federation, Washington DC; and Bruce M Rich of the Natural Resource Defence Council, also in Washington DC.

Between them, those critics make some thirteen different, though closely related, recommendations as to the conditions which should be satisfied before a dam is authorised. Those recommendations are all very sensible but they raise a fundamental – and as yet unanswered -question; namely, how would their adoption affect the world’s increasingly ambitious dam building programme? Let us try and answer that question by considering the recommendations separately.

No dams without assessment

The first recommendation – made by Bramble, Blackwelder and Rich – is that no dam should be built until an adequate assessment of its likely environmental effects has been undertaken and made available to the public . [1] [2] [3] Clearly, such an assessment would only be of use if it could be made by an objective body. But can an objective body really be found? And would such a body even have the courage to advise the government, if need be, not to build a particular dam?

Countless environmental assessments have been made of water development schemes – though usually only after governments concerned have become committed politically and economically to building them. However, very few, if any, such assessments have actually concluded that a scheme should not be built at all . Indeed, the record makes it quite clear that the main motivation for commissioning environmental assessments is to rationalise decisions which have already been made. Invariably, those decisions are largely unconnected to a scheme’s capacity to achieve its overt goals: rather, they are based on political and economic considerations of an often dubious nature.

Back to top

Dams for the poor?

The second recommendation – this time by Williams – is that water-development projects should only be undertaken if they can be shown “to benefit large sectors of the population instead of the urban elite “. [4] That condition is extremely unlikely to be satisfied – particularly in the Third World.

Such projects cannot benefit the people whose homes and land are flooded to create a dam’s reservoir; nor those in the immediate vicinity of a dam, most of whom will see their land taken over by plantations and eventually degraded into little more than a salt desert; nor those who will fall victim to the inevitable outbreak of water-borne diseases. Nor will it be the rural peasants of the Third World who benefit from the manufactured goods produced by the industries which a dam powers; not only are peasants unable to afford such goods but, once in the cash economy, they are often unable even to buy the food they need to survive.

The only people likely to benefit from major water development projects are thus the affluent few who can afford to obtain water for domestic use; those industrialists who obtain water and electricity for their factories; those plantation owners who get the bulk of the irrigation waters; the donor governments abroad whose industries put up the dams and provide most of the equipment used to build them; and, finally, those local politicians who reap the short-term political capital to be gained from the project – quite apart from any bribes and “commissions” which may come their way.

Back to top

Supporting labour-intensive industries

The third recommendation -made by Williams – is that the scheme should favour labour-intensive rather than capital-intensive economic activities. [5] Again, this is a recommendation which is unlikely to be observed: indeed, if it were, then all large-scale water development projects would have to be abandoned. Labour-intensive agriculture does not require water from large-scale irrigation works nor does labour-intensive manufacturing require hydro-electricity from large dams. Moreover, large-scale water development projects are only economic if they are farmed by capital-intensive agricultural enterprises which are fully competitive on the world market. Large-scale dams are thus quite incompatible with labour-intensive development projects.

Back to top

No export crops

The fourth recommendation – proposed again by Williams – is that future water development schemes should permit the production of food crops for feeding the local population rather than for growing export crops. [6] This is not possible for very much the same reasons that labour-intensive farming is not possible:

  • Firstly, peasants producing food for local consumption cannot afford farmland irrigated by massive water development schemes: it is quite simply too expensive.
  • Secondly, the foreign exchange needed to pay the interest on the loans contracted to finance a dam (and, more important still, to finance further development projects) can only be earned by exporting crops. Invariably, therefore, the land Irrigated by large-scale water development schemes ends up being taken over by plantations producing crops for export – and that inevitably means that less food is available for local consumption.

To observe this fourth recommendation would thus mean foregoing nearly all future large scale water development schemes.

Back to top

No damage to public health

The fifth recommendation – made by Blackwelder – is not to build schemes which “would compromise public health and safety in ways that would be viewed as unacceptable to the people affected”. [7] [8] This recommendation cannot conceivably be observed. An increase in the incidence of water-borne diseases appears an inevitable concomitant of water development schemes. Indeed, the title of a talk by Letitia Obeng of UNEP –“Starvation or Bilharzia?” – is indicative of the view held by many authorities that Bilharzia (or schistosomiasis) is an unavoidable consequence of our attempt to feed the starving millions by putting up vast irrigation schemes. Professor Gilbert White even tells us:

“The invasion by schistosomiasis of irrigation schemes in arid lands is so common that there is no need to give examples. The non-invasion of schemes in a region where the disease exists is exceptional.” [9]

Efforts to control such diseases by the use of molluscicides, nematocides, insecticides and other biocides, have been singularly unsuccessful. Moreover, since many of those biocides are either known or suspected carcinogens and mutagens, their routine use over a long period will almost certainly give rise to other equally serious health problems.

Back to top

Respecting heritage areas

The sixth recommendation – made by Bramble, Rich and Blackwelder – is that dams and other water development schemes should not be built if they adversely affect national parks, heritage sites, areas of scientific and educational importance, tropical rain forests or areas inhabited by wild animals threatened with extinction. [10] [11] [12]

The destruction of such valuable natural assets is almost inevitable where dams are concerned. Moreover, since the number of suitable sites for building dams is limited – a problem which will increase as the most obvious sites are used up – so dams will be built in areas which are less and less suitable. As that happens, the likelihood of one of the areas blacklisted by Bramble and his colleagues being selected as a dam-site must increase.

Back to top

Safeguarding against siltation

The seventh recommendation -Blackwelder’s – is that dams should only be built where it can be guaranteed that they will not silt up within a hundred years. [13] Although it is possible to observe that recommendation in temperate areas, it is very much more difficult to do so in the tropics where rivers carry high quantities of silt. Indeed, on the basis of the experience of the last 30 years in the tropics, it would seem almost impossible to build dams whose reservoirs do not silt up prematurely.

To satisfy Blackwelder’s recommendation would thus require – at the very least – the reafforestation of the whole catchment area of those rivers which are to be dammed – and not with shallow-rooting pines but with trees which reconstitute, as closely as possible, the original native forests. Significantly, the World Bank is beginning to insist on the reafforestation of watersheds: to date, however, the Bank has only recommended the planting of pine and eucalyptus – never, to our knowledge, native trees. We see little reason to suppose, therefore, that Blackwelder’s recommendation will ever be observed.

Back to top

Can salinisation be avoided?

The eighth recommendation – by Blackwelder and Rich – is that dams should not be built when their associated irrigation schemes are likely to lead to the salinisation of agricultural land. [14] [15] Unfortunately, the building of large dams in hot dry areas almost invariably leads to waterlogging and salinisation. Professor Aloys Michel of the University of Rhode Island, for example, warns that:

“waterlogging or salinisation, or both problems, will inevitably arise in all but the truly exceptional surface water irrigation system. . .”

Professor Victor Kovda of Moscow University feels the same way.

“During many centuries and even millennia, only areas having a free outflow of groundwater as in Tashkent and Samarkand have not undergone salinisation or waterlogging . . . increasing salinity in irrigated soils on arid lands is practically universal.” [17]

As salinisation inevitably builds up, it seems probable that almost all the land put under irrigated agriculture since the war will eventually have to be abandoned, possibly in the next decades. Effective methods for reducing salinisation (such as the lining of irrigation canals and building horizontal drains) are too expensive and are rarely adopted on any scale; others – such as the reduction of the amount of land under irrigation to make water available for flushing out salts or the observation of long periods of fallow – would so reduce economic output as to be impractical under a regime of capital-intensive market-orientated agriculture.

Back to top


This brings us to the ninth recommendation – proposed by Williams – that the emphasis of funding should be “towards sustainable long-term resource enhancement rather than short-term resource exploitation”. [18] Simply on the basis of the predictable premature siltation of reservoirs and the salinisation of the land which dams serve to irrigate, large water development schemes cannot – by any stretch of the imagination – be regarded as sustainable . In fact, it would be difficult to imagine any development schemes that more clearly involve “short-term resource exploitation”.

Back to top

No harm to tribal peoples

The tenth recommendation – by Blackwelder and Rich – is that dams should not be built “if they displace indigenous peoples from their homes and destroy their cultures” – or at least, as Rich puts it, where they “would displace or strongly disadvantage indigenous peoples or other vulnerable social minorities unless compensation is provided to ensure that the affected people are made no worse off; and preferably better off; than before the project”. [19] [20]

The cultural pattern of indigenous people is highly adapted to survival in the natural environment in which they live. To flood that environment and force the original inhabitants to live elsewhere – generally, as we have seen, in degraded (and degrading) conditions – is thus, among other things, to force them to live in an environment to which their culture does not adapt them. Inevitably, their society disintegrates; invariably, too, those who have been resettled are slowly transformed into an aimless and rootless proletariat. To observe this tenth recommendation would thus mean to desist from building dams in areas inhabited by indigenous peoples.

Back to top

No design faults?

A further recommendation by Blackwelder – the eleventh in our list – is that dams which “have significant engineering or safety problems” should not be built. [21] This, of course, would rule out building dams in areas with any sort of seismic activity or in areas subject to landslides. Even then, however, the safety of a dam could not be guaranteed.

Dr. Jean-Pierre Rothe and Dr. David Simpson, both of whom have undertaken considerable research into the association between dams and earthquakes, agree that it is impossible to establish the exact conditions under which large dams can trigger off earthquakes. Indeed, it appears that dams can cause earthquakes even in areas where no seismic activity has ever been recorded.

Back to top

No damage to fisheries

The twelfth recommendation – by Blackwelder – is that dams should not be built where they are likely to inflict significant damage on estuarine or ocean fisheries . [22] All dams, however, must affect estuarine nurseries and fisheries by depriving them of the nutrients contained in the silt which the dams prevent from flowing downstream.

Moreover, the upstream abstraction of water for irrigation and urban and industrial uses also increases the salinity of the water flowing into estuaries. That water is also invariably contaminated by the toxic wastes (in the form of fertiliser and pesticide run-off and industrial effluent) which are an inevitable concomitant of both modern Intensive agriculture and modern industry. It follows that this twelfth recommendation is again unlikely to be observed.

Back to top

Protecting water quality downstream

Finally, it is recommended – by Rich – that dams should not be built if they are likely to harm “significantly” the environment of a neighbouring country without its full consent. [23] Unfortunately, no fewer than 214 rivers or lake basins in the world are shared by more than one country; 57 in Africa, 40 in Asia, 48 in Europe, 33 in North and Central America and 36 in South America.

Moreover, the territory of a very considerable proportion of the total area of many countries falls within such international basins: 80 percent of more than 10 African countries and 100 percent of another 10, for instance, and over 80 percent of at least 5 Asian countries and 100 percent of another 2.

Whenever several countries are situated along the same river basin, the water supplies available to the population of those living downstream must – as a result of the abstraction of water upstream for irrigation, domestic and industrial purposes – become scarce, salty and contaminated with agricultural and industrial wastes. To observe Rich’s recommendation would thus mean desisting from building dams on any of the world’s large international rivers.

Back to top


If water schemes were only built where they satisfied the above recommendations – if, in other words, dams were only built when they could be certain to provide water on a sustainable basis and without incurring intolerable social and ecological costs – then very few, if any, would be built.

Back to top


1. Barbara J. Bramble, Statement on behalf of the National Wildlife Federation before the Subcommittee on International Development Institutions and Finance of the House Banking Committee, Washington DC, 1983; p.20. 
2. Brent Blackweider, Testimony on behalf of the Environment Policy Institute before the House Committee on Banking, Finance and Urban Affairs, subcommittee on International Development Institutions and Finance, concerning the Multilateral Development Banks and large-scale water development projects, Washington DC June 27 1983; p.12. 
3. Bruce M. Rich, Statement on behalf of Sierra Club, World Wildlife Fund, US Friends of the Earth, Izaak Walton League of America, Natural Resources Defense Council Inc, National Audubon Society before the Subcommittee on International Development Institutions and Finance Committee on Banking, Finance and Urban Affairs, Washington DC June 28 1983; p.25. 
4. Philip B. Williams, Planning Problems in International Water Development. Philip Williams and Associates, Pier 33N, The Embarcadero, San Francisco, 1983; p.4.
5. Ibid., p.4.
6. Ibid., p.4.
7. Brent Blackwelder, op.cit., 1983; p.12.
8. Bruce M. Rich, op.cit., 1983; p.12.
9. Gilbert F. White, “The Main Effects and Problems of Irrigation”. In E. Barton Worthington (Ed) Arid Land Irrigation in Developing Countries: Environmental Problems and Effects, Pergamon, Oxford, 1977; p.48.
10. Barbara Bramble, op.cit., 1983; p.21.
11. Bruce M. Rich, op.cit., 1983; p.29.
12. Brent Blackwelder, op.cit., 1983; p.12.
13. Ibid., p.12.
14. Ibid., p.12.
15. Bruce M. Rich, op.cit., 1983; p.25.
16. Aloys Michel, “The Impact of Modern Irrigation Technology in the Indus and Helmand Basins of South East Asia”. In T. Farvar and J. Milton, The Careless Technology, Tom Stacey, London, 1973; p.273.
17. Victor Kovda, “Arid Land Irrigation and Soil Fertility”. In E. Barton Worthington, op.cit., 1977; p.219.
18. Philip Williams, op.cit., 1983; p.4.
19. Brent Blackwelder, op.cit., 1983; p.12.
20. Bruce M. Rich, op.cit., 1983; p.28.
21. Brent Blackwelder. op.cit., 1983; p.4.
22. Ibid., p.4.
23. Bruce M. Rich, op.cit., 1983; p.28, The Ecologist Vol. 14 No. 5/6, 1984.
  • Twitter
  • Facebook
  • Digg
  • Reddit
  • StumbleUpon
  • Diaspora
  • email
  • Add to favorites
Back to top