Salting the earth: the problem of salinisation

Under the terms of a joint treaty signed in the early 1970s between Mexico and the United States, the American government agreed to reduce the salinity levels of waters entering Mexico. To that end, a massive desalinisation plant is being built on the Mexican border at Yuma in Arizona. The plant is designed to treat 107,000 acre-feet of water (with an average salinity level of 2,800 ppm) a year: 92,000 acre-feet of water with a salinity of less than 800 ppm will thus be provided to the Mexicans.

Originally priced at 300 million dollars, the plant is now expected to cost more than one billion dollars. At that price, irrigation water provided by the plant will cost some $800 per acre-foot – more than 35 times the current cost of irrigation water in the Imperial Valley.

It is now quite clear that the Yuma desalinisation plant will not in itself even begin to solve the water and salt problems facing the Southwest. Indeed, several other much more ambitious schemes have been proposed for the area. Although those schemes are certainly intended to provide water for flushing out excess salts from the soil, their primary purpose is undoubtedly to further the extension of irrigated agriculture.

All involve importing vast quantities of water from other parts of the US; and, due largely to the Government’s concern for its escalating budgetary deficit, all have run up against financial problems. Indeed, with local tax payers unwilling to meet even a part of the vast costs of the projects – and federal funds less and less available – two of the schemes have already been vetoed as too expensive. No doubt, however, those vetoes will be reconsidered when – or, rather, if – economic conditions ever become more propitious. The schemes include the two following projects:

• The Peripheral Canal project, which would bring water from Northern California rivers around the San Francisco Bay Delta and down to Southern California, at a cost initially of between $700 million and $1.3 billion, was voted down in a statewide referendum in 1982.
• The Texas Water System, which is intended to provide water to the arid and semi-arid West of Texas. The scheme involves the building of a system of reservoirs and inter-basin water transfer facilities in the Eastern and Central parts of Texas: a coastal aqueduct stretching some 400 miles from the Sabine River to the Lower Rio Grande Valley; and a trans-Texas canal stretching mainly uphill from North-East Texas to the High Plains, with a branch running to New Mexico and another to the Trans-Peco area.Much of the 17.3 million acre-feet of water which would run annually through those canals would come from the Mississippi (some 12-13 million acre-feet per year) and would have to cross Louisiana before entering Texas. Because the course of the canal would be largely uphill, almost two-fifths of the state’s total electricity supply (as of 1970) would be required to pump the water along the canal. Like the Peripheral Canal Scheme, the Texas Water System has been vetoed by local taxpayers, who simply refused to finance a $3.5 billion bond issue to fund the project.

Another proposal is the North American Water & Power Alliance (NAWAPA). Proposed by the Ralph M. Parsons Company of Pasadena, California, the NAWAPA scheme is one of the most ambitious of all time. It would divert water from Alaska and Northern Canada to various parts of Canada, the US and Mexico. Hydro-electric plants built along the giant canal would provide – over and above what would be required for pumping – a surplus electricity capacity of 70,000 megawatts, the equivalent output of 70 large nuclear power stations. The drainage area of the scheme would be 1.3 million square miles and 160 million acre-feet of water would be diverted southwards for irrigation and ‘water-way control’. The estimated cost of the project is $200 billion: if, however, the experience of similar projects is anything to go by, the final cost could well be 3 to 4 times higher.

It goes without saying that the environmental destruction which would be caused by such wholesale interference with the ecology of the regions through which the NAWAPA scheme would pass would be little short of disastrous. Moreover, the scheme is likely to be strenuously opposed by Alaska and Canada who do not take kindly to the idea of their waters being diverted to the Southwest. Indeed, it seems that there is little chance of the NAWAPA project ever getting off the drawing board.

Nonetheless – and this is particularly significant – Pillsbury insists that, without the NAWAPA scheme, the future of the Southwest is extremely precarious. In his opinion, it is quite simply

“the only concept advanced so far that will enable the lower reaches of western rivers to achieve the salt balance necessary for the long-term health of western agriculture, on which the entire US and indeed the world has much dependence. Unless the lower rivers are allowed to reassert their natural function as exporters of salt to the ocean, today’s productive lands will eventually become salt-encrusted and barren.” [63]

Sind, Pakistan – Geography has condemned Pakistan’s Sind province to being a ‘sink’ for the whole Indus river valley. As a result of economic development within both Afghanistan and the Punjab – the two upstream states which also share the Indus – its waters are increasingly polluted. Although the Tarbela Dam is intended to ensure a supply of 92 million acre-feet of good quality water to the Sind, few experts expect the dam to provide a permanent solution to the problem. Indeed, even with the dam, it will be necessary to mine the extensive groundwater reservoirs beneath the Punjab.

After the year 2000, however, that supply is likely to start running out – although some 20 million acre-feet per year of groundwater recharge will still be available. At that point, it will only be a question of time before the inevitable happens:

“Sooner or later, the concentration of salts, due to repeated capillary rise and evaporation followed by repeated irrigation and leaching, is bound to increase . . . downstream.” [64]

The only solution – or, rather, palliative – would be to ‘export’ that highly saline water directly to the sea or to allow it to accumulate in sinks along the desert margins. The cost of either undertaking would be enormous. Not surprisingly, Aloys Michel concludes that such wasteways ‘are likely to be postponed’. In that event, it is hard to see how further salinisation can be avoided in the area.

Iraq and the Euphrates – Like Sind Province, Iraq is at the tail-end of a shared water supply. Thus, the River Euphrates must pass through both Turkey and Syria before it crosses into Iraq. Until the end of the Second World War, only Iraq abstracted water in any quantity from the river. Since then, however, both Syria and Turkey have put up large dams – the Keban Dam in Turkey, for instance, and the Tabaqua Dam in Syria – in order to exploit the waters of the Euphrates fully.

In the 1960s, both countries together abstracted 16,000 million cubic metres a year, which, at that time, represented 45 percent of the average annual discharge of the Euphrates into Iraq. Should plans to build new dams in all three riverine states go ahead, then, according to Professor Peter Beaumont of Bangor University, “the likely demand for water will be in excess of the available flow of the river”. Inevitably, Iraq will suffer most: very little water will be left for her use and what water there is will have high salt and pollution loads. One consequence will be a corresponding fall in the quantity and quality of food produced in the area.

South Australia and the Murray River – South Australia is one of the driest states in what is probably the driest continent in the world. Sixty-six percent of its water supplies are derived from the Murray River – with that figure rising to approximately 83 percent in a dry season. Before it reaches South Australia, the Murray flows first through the States of Victoria and New South Wales, which together contribute 64 percent of the 1.1 million tons of salt carried by the river each year.

As a result of abstraction for irrigation, domestic consumption and industrial use, the amount of water reaching South Australia has been drastically reduced: moreover, what water does arrive is seriously polluted with agricultural and industrial wastes. South Australia has no say in controlling that pollution – nor is there any inter-state body which could enforce pollution controls upon the two offending upstream states.

Thus, the Murray River Committee – to which all three states send representatives – only has responsibility for allocating the amount of water used by each of the riverine states: it has no brief to ensure the quality of the Murray’s waters. Indeed, in 1980, the new South Wales representative on the Committee officially stated:

“Water pollution control in South Australia is a matter for that state alone.” [66]

The groundwater in South Australia is naturally saline – in some cases, it is saltier than sea water. Inevitably, as irrigation water seeps back into the Murray, it brings with it much of the salt in that groundwater. In an attempt to overcome that problem, tiled drains were installed underneath irrigated lands, the water being pumped from them into evaporation basins on the river flats.

Those basins were not watertight, however, and highly saline water is already seeping out of them into the Murray. Furthermore, the basins do not have the capacity to hold all the saline water from the State’s irrigation schemes: the rest is thus released directly into the river. Saline water is also reported to be seeping from the basins into the water table, leading to the formation of ‘groundwater mounds’ from which there is further seepage into the Murray.

With ever greater demands being made on the waters of the Murray River for domestic, agricultural and industrial purposes, the river’s flow is inevitably being reduced. Since the amount of salt carried by the river tends to remain constant – at about 3,000 tonnes a day – salinity can only increase. The prospects are grim, according to M. Butler, a geographer at Adelaide College.

“In an uncertain economic climate and in the face of rising salinity levels and increasing demand for good water for metropolitan Adelaide, the farmer’s future looks decidedly shaky . . . Irrigated lands will eventually be abandoned and farmers will lose their way of life.” [67]

That last comment could apply to any one of the examples we have considered. Indeed, by opting for technological solutions to what are essentially ecological problems, the further salinisation of lands throughout the world is ensured. In effect, we have become trapped on a technological treadmill, which can only result in long-term ecological destruction.

In that respect, the experience of the US Southwest is, as we have seen, particularly eloquent. Thus, in their thirst for water, the inhabitants of the Southwest have sunk tuba-wells and built huge reservoirs. In their fight against salinisation, America has spent a fortune on technological measures of a type which less prosperous countries can ill-afford. Thus, they have lined irrigation canals, dug horizontal drains and built evaporation basins.

Now that those measures have failed to solve the Southwest’s water and salinisation crisis, the search for new ‘technical fixes’ has become increasingly desperate: river basin transfers and the development of genetically-engineered salt-tolerant crops have become the order of the day but at what financial – let alone ecological – cost?

Sooner or later, the technical fixes will run out: even now, as we have seen, many are proving too costly to implement – witness the massive water transfer schemes which have been proposed for the area. The future is thus bleak for the US Southwest – as, indeed, it is for Sind, Iraq and South Australia. How long will it be before vast areas of those regions are abandoned, their best farmlands being transformed into uninhabited salt encrusted deserts.

References

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