The lessons of traditional irrigation agriculture: learning to live with nature

Introduction

At a recent meeting on water development schemes, Raymond Nace, a hydrologist, issued a stern rebuke to his assembled colleagues.

"Three sins beset water planners and their advisors: faith in science and technology; worship of bigness; and arrogance towards the landscape. The belief that technology can solve any water problem ... is wrong. It seems essential that a new frame of mind, some new perspective, be applied to water planning." [1]

Strong words indeed - and ones with which we would not disagree. But what principles should govern the "new frame of mind" that Dr. Nace calls for? To answer that question, it is not enough to examine only those features which have caused modern irrigation schemes to fail: much more important is an understanding of the features which have made traditional irrigation societies succeed.

Why, for example have the El Shabana, the Sonjo or the Chagga proved themselves capable of practising sustainable irrigation agriculture over thousands of years, whilst modern irrigation schemes have frequently lasted no more than a few decades? Is it, as Fernea suggests, because tribal societies have achieved "a congruence of fit" between their methods of cultivation, their land tenure systems and "the nature of land, water and climate"? [2] And, if so, what is the basis of that 'congruence of fit'?

Size: a critical factor?

One of the most striking features of traditional irrigation systems is that they operate on a very small scale. By contrast, most modern irrigation schemes cover large areas of land and are geared towards maximum production. In that respect, it is hardly surprising that their ecological impact is greater than that of traditional systems. The point is well made by Dr. Desmond Anthony:

"Experience has shown ... that the extent and degree of modification (of ecological systems) and the magnitude of the resultant impact are usually directly proportional to the size of the project, and are related to the nature of the environment and its sensitivity to modifications of the kind brought about by construction, operation and maintenance of such projects." [3]

Robert Goodland is of the same mind. Indeed, in his opinion, "the size of hydro projects is almost exponentially related to environmental impact". [4] That general rule, he writes, is true of "the area of fertile soil removed from annual production by flooding; the number of people displaced and houses, infrastructure lost to the reservoir; and the opportunities for proliferation of aquatic disease vectors (e.g. malarial mosquito, schistosomiasis snail) and nuisance organisms (e.g. water hyacinth, gnats)".

He goes on to point out that large reservoirs "trigger or exacerbate the perils of induced seismicity" and "produce less fish per unit volume than small reservoirs". Moreover, "water quality deteriorates gravely in large reservoirs while remaining acceptable in small ones".

For those reasons alone, says Goodland, damns should be as small as possible. Better still, tube turbines should be installed:

"These cheap, low-maintenance, sparkless sources of power are easy to manufacture in the 100kw to 1,000kw range, and 20mw to 100mw sizes also can be feasible with minor environmental impact."

Indeed, Goodland claims, the smaller turbines cause "practically no environmental problems since little or no reservoir is created".

Despite the environmental advantages of building small dams, small-scale irrigation and hydropower schemes are rarely favoured over large-scale schemes. One reason, undoubtedly, is that large-scale projects earn greater kudos for politicians and engineers alike: the more grandiose the scheme, the more prestige accrues to those involved in building it. So too, as William Ackermann points out, small-scale dams are frequently seen as being 'uneconomic':

"From the viewpoint of power generation and large-scale water storage, only relatively large and deep reservoirs are economically attractive. One horsepower is generated by dropping 1 cubic foot of water per second through a height of 3.34 metres. Thus there are obvious advantages to constructing power dams with as much 'head' as possible. Similarly, for water storage, the approximately parabolic shape of most lake basins, ensures that each increase in the height of a dam progressively increases the storage benefits. In consequence, major reservoirs are usually made as extensive as possible and thus they tend to be in the large-scale range." [5]

Why small is not enough

But even supposing that, in future, only small-scale dams were to be built, would that enable us to avoid the problems associated with today's 'superdams'? The answer is undoubtedly a guarded 'No'. Small is certainly preferable to big - and on that point we should be quite clear - but smallness does not in itself provide a foolproof insurance against ecological damage. Indeed, the record makes it quite clear that even small-scale projects can cause significant ecological and social harm. In some cases, the damage done is the result of poor design: in others - as in the first of the following three examples - it arises from the very fact that the schemes involved are small-scale.

• According to John Hunter, the small dams which have been built in the Volta Valley provide a more suitable niche for the vector of onchocerciasis than large dams. "In many areas," he reports, "the construction of small dams has already augmented the spread of river blindness rather than the reverse". [6] The reason is clear enough: the more dams there are, the more spillways there will be - and hence the more breeding places for the black flies which carry the disease.
• In Jamaica, bad design led to the failure of a series of small dams which had been built across various shallow valleys in order to make reservoirs for irrigation from modest creeks. Because the sub-soil of the region is particularly porous - a fact which the dams' promoters failed to take into account - the water simply leaked away from the reservoirs. As a result, reports Brian Johnson of IIED, the dams now "sit high and dry, a series of embarrassing embankments". [7]
• In Eastern Nepal, a small hydro-dam silted up so quickly that the turbines stopped functioning. According to far-away economic experts, the dam was supposed to have repaid its initial investment within 15 years: in just five years, however, it had become "a millstone of modernity around the Nepalese neck".

Seasonal vs. perennial irrigation

Even the small-scale irrigation schemes built today aim at replacing seasonal irrigation with perennial irrigation. Such perennial irrigation, however, invariably entails higher social and ecological costs - whatever the size of the scheme involved.

Perennial irrigation schemes create a permanent (rather than a temporary) niche for the vectors of the principal water-borne diseases - thus inevitably causing an escalation in the incidence of those diseases. That problem is exacerbated by the fact that perennial irrigation drastically increases the amount of time that local farmers must spend in the irrigation waters - and hence the amount of time that they are exposed to the vectors which those waters harbour. It also increases the moisture level of the atmosphere and the soil, and the vegetative period of crops, thus providing a permanent niche for pests.

Although perennial irrigation makes possible several harvests a year, that achievement quickly turns sour where the soil is too poor to support the extra demands being made upon it. In that respect, it is important to note that very few soils - and, in particular, the organically poor soils of the tropics - can be used to produce 2 to 3 identical crops a year for very long. Indeed, if multi-cropping is carried out over any significant period of time in such regions, it can only lead to the degradation of agricultural land - which, in turn, must lead to a reduction rather than an increase in yields.

Equally important, multi-cropping and perennial irrigation tend to raise the water table, inevitably giving rise to all the attendant problems of waterlogging and salinisation. Furthermore, multi-cropping cannot avoid increasing the workload of local farmers, to the detriment of their social lives. The resulting social impoverishment frequently exacerbates the problems of social disintegration, thus rendering impossible the co-operation which is so vital to the sound management and maintenance of a viable irrigation system.

For the above reasons, the very principle of perennial irrigation is unacceptable - on whatever scale it is carried out. That stark reality is tacitly recognised by traditional irrigation agriculturalists. Indeed, for them, irrigation is invariably seasonal and, moreover, it is limited to the shortest possible period. Thus, in the majority of traditional irrigation societies, we find that half the potential agricultural land is allowed to lie fallow on alternate years, thereby ensuring that irrigation is carried out for a short season every other year.

It goes without saying that such an apparent 'waste' of good land is considered intolerable by those who manage today's modern irrigation systems. Indeed, the very idea of 'fallow lands' and 'alternate year irrigation' goes against all the cannons of the modern market system, geared as it is towards increasing production regardless of long-term ecological and social costs.

The preservation of forests

A further essential feature of traditional irrigation agriculture is that it is practised in areas where part, at least, of the natural forest cover has been allowed to remain intact. Such forests are particularly important in the uplands and in the watersheds of the river whose waters are abstracted.

Indeed, deforestation is by far the most important cause of the recurrent and ever more destructive droughts that today afflict vast and highly populous areas of the Third World.

It contributes to such droughts in a number of ways. Firstly, it reduces rainfall. Thus, in Amazonia, 75 percent of the precipitation is estimated to be derived from the transpiration of trees in the area, which means that once the Amazonian forest is cut down one can expect a significant reduction in rainfall throughout the region.

(The vast volume of water that is continuously being exchanged between the forest and the atmosphere, over an area of something like two million square miles, serves as a massive cooling system for the entire planet which means that the destruction of the Amazonian forest must seriously affect world climate. A preliminary mathematical model developed by one group of researchers suggests that the destruction of Amazonia should increase the mean temperature in the tropics to something like 50ºC, making them virtually uninhabitable. The United Nations University in Tokyo is currently studying this very alarming issue.)

It appears that the Harappan Desert in Pakistan was also once a vast rainforest whose rainfall was also largely self-generated, so that once the trees were cut down, rainfall was reduced to near zero. [8]

But the recurrent droughts are not necessarily the result of reduced rainfall. Droughts are regularly reported in areas where there has been no recent reduction in rainfall. Such droughts are simply the result of a lowered water-table caused by deforestation, excessive water-abstraction, or else they are due to the reduced water-retaining capacity of an overtaxed soil.

The general desiccation caused by deforestation in India was eloquently described by E. Wasburn Hopkins 80 years ago:

"All that great bare belt of country which now stretches south of the Ganges - that vast waste where drought seems to be perennial and famine is as much at home as is Civa in a grave-yard - was once an almost impenetrable wood.

Luxuriant growth filled it: self-irrigated, it kept the fruit of the summer's rain till winter, while the light winter rains were treasured there till the June monsoon came again. Even as late as the epic period, it was a hero's derring-do to wander through that forest-world south of the Nerbudda, which at that time was a great inexhaustible river, its springs conserved by the forest. Now the forest is gone, the hills are bare, the valley is unprotected, and the Nerbudda dries up like a brook, while starved cattle lie down to die on the parched clay that should be a river's bed." [9]

The deforestation of upland areas is even less tolerable, since forested uplands attract a great deal of rain and it is in the uplands that the sources of the rivers, which water the plains beneath, are situated.

We have seen how this is so in Sri Lanka and how the water required for the vast water-development schemes being built today, is unlikely to be available now that the uplands have been deforested. One might add that already, the autumn monsoon - which blows from the South West and which used to collect moisture from the forest uplands and deposit it on the dry zone beyond - now falls on denuded mountains. Hence, the autumn rains have largely vanished from the north east of the island.

We have also noted how such deforested slopes are, in the tropics in particular, very rapidly eroded and that the soil which is washed off them raises the river beds, causing floods that can be as devastating to agricultural production as are the droughts, to which the same areas have become so prone, during the dry season.

Ironically, deforestation is at once the cause of both the floods and the droughts that combine annually, to deprive the inhabitants of vast areas of the Third World of considerably more food than could conceivably be provided by the implementation of FAO's plans to increase, by 50 percent or so, the agricultural area at present under irrigation.

What is more, the forests can provide water in perpetuity - not just temporarily - and at no social and ecological cost. On the contrary, they provide other equally precious benefits. For instance, they harbour a wealth of wildlife. They are a source of all sorts of wild fruits and berries, of humus for the fields and of timber for building houses.

On a wider scale, they generate oxygen and absorb carbon dioxide and generally exert a stabilising influence on climate. In addition, all these benefits are free and are thus available to all - not just to the urban elite which alone benefits from the building of large dams

Balancing water consumption with water availability

A further characteristic of sound irrigation systems is that those who operate them do not draw off more water than is guaranteed by the natural rate at which their water supplies are replenished. In other words, they do not try to extract more than the 'safe yield' of their aquifers and surface waters.

To that end, traditional societies have historically sought to prevent any increase in the demand for water. In his study of irrigation agriculture in Mediaeval Valencia for example, Thomas Glick shows how all new developments which might have placed a strain on the region's 'water budget' were strenuously resisted. [10] So too, Hunt and Hunt note the general tendency within traditional irrigation societies "to resist new [water] uses" - even where that entails refusing to open up new lands or to plant new crops. [11]

In arid lands, such restraint is clearly axiomatic if water supplies are not to be overtaxed and if the long-term availability of water is to be assured. That simple axiom, however, is one which modern industrial society - with its emphasis on growth - has preferred to ignore. Instead, it has hoodwinked itself into believing that water should not (and, indeed, does not) place a constraint on Man's activities. The philosophy is simple enough: if water is not available locally, then Man's ingenuity will ensure that it is supplied from elsewhere.

In that respect, it is worth considering the history of agricultural development in the US Southwest - a history which illustrates perfectly the conflict between what might, respectively, be called the 'ecological' and the 'industrial' view of water demand and water supply.

In the late 1880's, ecologically-minded people - notably John Wesley Powell, who later became the Director of the US Geological Survey - began to warn that the arid Southwest must learn to live within its water budget if future shortages were to be avoided. Emphasising the natural limits of the arid West's water resources, Powell wrote:

"Only a small portion of the country is irrigable. The irrigable tracts are lowlands lying along the stream. These lands will maintain but a scanty population." [12]

That eminently ecological view of water supplies was not to the liking of Powell's contemporaries. Indeed, as the historian Henry Nash Smith observes, Powell "was asking a great deal: he was suggesting that the West should submit to rational and scientific revision of its central myth" - the myth that there was enough land and water available for everyone's needs. [13]

Perhaps it was inevitable then, that Powell lost his battle to make the farmers of the Southwest see sense. His recommendation that the West should tailor its development plans "to fit the limits of its natural resources" was rejected by the US Congress, "with senators and congressmen from the region itself providing the stiffest opposition". [14]

At the 1893 International Irrigation Congress held in Los Angeles, Powell was greeted with catcalls and boos. He was, however, undeterred. "I tell you, gentlemen," he warned, "you are piling up a heritage of conflict and litigation over water rights, for there is not sufficient water to supply the land." [15]

By rejecting Powell's advice, the American establishment effectively chose to turn a blind eye to the nature of land, water and climate in the Southwest. Underlying that intransigent denial of ecological realities, was the growing belief that the natural world was something to be shaped at Man's whim to satisfy his immediate requirements.

With the development of modern science - and, in particular, the belief that technology can free Man from previous ecological constraints - that attitude has become more and more firmly entrenched. Even well-established hydrological principles have been abandoned where they reflect the need to limit water demand. Some 20 years ago, for example, the US Geological Survey (USGS) simply dropped the notion of 'safe yield'. By way of explanation, H. E. Thomas of the USGS wrote:

"Wholesale depletion [of groundwater] may be economically feasible in the long view, if it results in building up an economy that can afford to pay for water from a more expensive source." [16]

Such a view is hard to swallow. What happens when the "more expensive source" is depleted? Even supposing that another (presumably even more expensive) source of water is available, it can surely only be a question of time before the economy becomes dependent on a source that is so expensive, that no-one can afford to buy its water, at which point, the whole economy simply collapses.

It is a situation which, as we have seen, has already almost been reached in the US Southwest. Even though many billions of dollars have been spent on numerous water development schemes in the area (California has the dubious privilege of possessing almost one-tenth of the world's large dams) irrigation agriculture in the Southwest can - in the view of many experts - only continue on any significant scale if the Federal Government is willing to subsidise such mammoth schemes as the Peripheral Canal and the North American Water and Power Alliance. Already the former project has been vetoed at the State level as being too expensive. Even if the money was available from the federal coffers, who would be able to afford the water?

Design and management: village elders vs. distant bureaucrats

If traditional irrigation systems run so smoothly, it is largely because those who manage them are not members of an alien bureaucracy which has been imposed upon local farmers by the State. Instead, they are closely integrated members of the very community which farms the land: consequently their own personal interests largely coincide with those of their fellow farmers.

Furthermore, the knowledge they employ in designing and operating their local irrigation system, is knowledge which has been handed down from generation to generation. It therefore reflects the total experience of running an irrigation system in the specific geological, biotic and climatic conditions under which the society must operate. Finally, those who manage a traditional irrigation system have a vested interest in its success: if they fail to do their job properly, then it will not only be their neighbours who suffer but their own families as well.

By contrast, modern irrigation schemes are invariably run by distant bureaucracies whose officials are uninvolved and uninterested in the daily life of the communities they oversee. Moreover, the tendency for bureaucracies to seek to perpetuate themselves has frequently meant that senior officials have ridden roughshod over local ecological and social considerations.

So too, in the pursuit of short-term political gains, and in the desire to expand the influence of their own departments, those same officials have shown themselves singularly susceptible to lobbying by powerful commercial pressure groups. Inevitably, one finds that the latter's financial interests are then often put above those of the local communities which a particular irrigation scheme is intended to serve.

What is true for the upper echelons of a bureaucracy also tends to be true - though to a lesser extent - at the local or regional level. As we have seen, the inability of local bureaucrats to manage irrigation works with the same degree of equitability and efficiency displayed by traditional irrigation societies, is legion. And is there any wonder?

Unlike those who manage a traditional irrigation system, the bureaucrats in charge of a modern irrigation scheme are unlikely to have any practical experience of agriculture in the region: nor are they able to draw on the storehouse of information which a traditional society builds up by farming the same land year after year. Instead, they must rely on the few vague generalities which they gleaned from textbooks written by academics who rarely have any knowledge of local conditions.

Even where that general knowledge is supplemented by feasibility studies carried out prior to the setting up of a scheme, the hapless bureaucrat is still in an unenviable position. For, as we have seen, few such studies give any real indication of the problems involved in irrigation agriculture, their primary function being to justify decisions which have already been taken at a higher political level.

The result is frequently a cynical shell-game, in which bureaucrats pass their brief period 'in the field' by passing the buck for failures from one department to another, whilst doing their utmost to claim credit for any successes. Therein lies the path to promotion.

Nor should we be surprised by such naked opportunism. It makes little difference to a bureaucrat whether a new irrigation scheme fails or succeeds. If it fails, it is likely that the bureaucrat will have moved to another post long before the failure can be blamed on him: he is not accountable - and it will not be him who suffers the consequences of failure. Unlike the peasants who must make their livelihood from the land they farm, the bureaucrat's income is assured - and with it, his sustenance.

Food for local consumption rather than for export

Perhaps the most important feature of traditional irrigation agriculture, is that it is geared to producing food for local consumption rather than for export to some distant land. Indeed, it is only by eschewing the export market that irrigation schemes may fulfil the purpose for which they are overtly designed: namely to serve the interests of local people.

It is also the only way in which it is possible for irrigation agriculture to display those features which we have listed above, and which we regard as essential, if an irrigation scheme is to satisfy the requirements set out by Brent Blackwelder, Philip Williams, Barbara Bramble and Bruce Rich - in other words, if they are to be effective and sustainable.

To produce enough food to feed itself, a society need not of necessity devastate its environment. Once, however, it becomes geared to producing food for export to a highly competitive - and, at times, seemingly insatiable - world market, such devastation is unavoidable. Indeed, to export successfully, agricultural activities must be undertaken by vast, capital-intensive enterprises and society must be willing to subordinate long-term social and ecological considerations to the overriding goal of short-term economic competitiveness. Otherwise, such enterprises simply would not survive.

Under such circumstances, the dams that store the water for irrigation schemes cannot be small. Everything conspires to make them bigger and bigger. Nor can irrigation systems possibly be seasonal: perennial irrigation is essential if vast stretches of water-intensive monocultures are to be multi-cropped year after year.

Nor, too, can forests be preserved. Put bluntly, there is no room for them. Moreover, exporting their timber provides an essential source of the foreign exchange needed to finance capital-intensive development schemes.

Nor can the over-use of water be avoided. All the water that can be made available must be abstracted in the interests of economic competitiveness and of maximising economic activity.

Finally, nor can export-orientated irrigation schemes be managed by local communities. Widstrand, for example, notes the failure of 'water-user associations' in the Third World and the high death-rate of government-introduced co-operatives in East Africa.

But should we ever have expected such schemes to succeed? Why should peasants willingly associate themselves with projects designed to export food, grown on the only land available to them for producing the where-with-all to feed themselves and their families, in exchange for money which will be spent by an urban elite on expensive imported goods? To expect peasants to co-operate in such a venture is surely utopian.

The need for a new world view: the ecological approach

Inevitably, the conflict between the 'ecological' and 'industrial' views of water supplies in the US Southwest raises more general questions about our attitudes towards both nature and economics.

• Can we really take the view that it is justifiable to jeopardise future water supplies in the interests of economic growth?
• Is it really 'economic' to expose vast numbers of people to malaria or schistosomiasis, in exchange for the hydro-electricity or irrigation water that a dam provides?
• Where is the 'economy' in transforming good agricultural land into a salt desert for short-term increases in agricultural yields?

Clearly, our ideas of what is 'economic' need serious re-thinking. The point is well made by Robert Goodland:

"Economics exclude consideration of ... adverse consequences - frequently referred to as 'externalities' - from customary evaluations. The time-frame of economic thinking is so short-sighted, and the perspective of economic vision is so narrow, that such criteria frequently act to the detriment of the environment." He goes on to note: "In the final analysis, anything environmentally unsound can never be economically healthy." [17]

Sooner or later, all social and ecological costs must be translated into economic costs - be it in terms of higher health bills or diminishing agricultural returns. By incurring such costs, we are effectively signing post-dated cheques against future generations - cheques which will one day be presented for payment.

When that day comes, it is unlikely that we will have put enough money aside to meet the debt we have built up - indeed, we will probably have forgotten that we even 'signed' the cheques in question. The only outcome of such short-sighted behaviour is ecological and social bankruptcy - and such must eventually be the fate of all countries that place day-to-day economic and political considerations above the long-term health of our physical and social environment.

That inexorable truth is well illustrated by the history of the 'dustbowl years' in the United States. On basic ecological grounds, the fragile soils of the southern plains should never have been put under the plough - a fact which was recognised by the Mexican government as far back as 1825 when it decreed that its plains should only be used for ranching. John Wesley Powell (among others at the US Geological Survey) was also of the opinion that ranching offered the only sustainable means of farming the southern plains.

To the American government, however, ranching smacked of feudalism: it suggested an 'undemocratic' policy which would result in the setting up of 'great land-owning barons' whose interests could only conflict with those of the small homesteader. Even religion was used to justify the popular view that the plains should be cultivated: God, it was claimed, intended "not cattle but wheat" to be raised on the plains.

The plains were thus cultivated - and the great dustbowls of the 1890s and 1930s were the inevitable consequence. When, in 1936, the Great Plains Committee (under the chairmanship of Maurice Cooke) reported on the ensuing tragedy, it vindicated the warnings of Powell:

"Nature has established a balance by what, in human terms, would be called the method of trial and error. The white man has disturbed this balance - he must restore it or devise a new one of his own."

The Great Dustbowl, the committee insisted, was a wholly man-made disaster, the result of a series of misguided efforts "to impose upon the region a system of agriculture to which the plains are not adapted". [18] Significantly, Cooke and his colleagues went on to criticise the prevailing attitude "that nature is something of which to take advantage and to exploit - that Nature can be shaped at will to Man's convenience". They went on to comment:

"In a superficial sense, this is true - felling of trees will clear land for cultivation, planting of seeds will yield crops, and applications of water where natural precipitation is low will increase yields. However, in a deeper sense, modern science has disclosed that fundamentally Nature is inflexible and demands conformity ... We know now, for instance, that it is essential to adjust agricultural economy on the Plains to periods of deficient, rather than of abundant, rainfall, and to the destructive influence of wind blowing over dry loose soil, rather than primarily to a temporary high price for wheat or beef - that, it is our way, not Nature's which can be changed."

Herein lies the crux of the matter. Living things are not arranged in a random manner. Nature is not totally malleable as those who wish to transform her would have us believe. She is, on the contrary, highly organised - and maintaining that organisation is critical to her proper functioning. Once degraded by over-exploitation and pollution, Nature cannot hold her own.

Cut down forests and overtax the land and soils will become eroded: pollute rivers and fish will die: upset the natural balance between pest and predator and pest epidemics will break out; destroy the habitat of wildlife and species will pass into extinction. Indeed, the whole gamut of ecological ills which now beset the earth should be seen as but the symptoms of a degraded Nature which, under pressure from industrial Man, can no longer continue to function properly.

If those ills have, historically, been avoided by traditional societies, it is above all because they recognised the simple axiom that "it is our way not Nature's which can be changed".

References