Irrigation is at the heart of the sustenance of civilisations. Glancing back at its history reminds us of the precariousness of the environment, writes John Harris* I met a traveller from an antique land Who said: Two vast and trunkless legs of stone Stand in the desert. Near them, on the sand, Half sunk, a shattered visage lies, whose frown, And wrinkled lip, and sneer of cold command, Tell that its sculptor well those passions read, Which yet survive, stamped on these lifeless things, The hand that mocked them, and the heart that fed, And on the pedestal these words appear: "My name is Ozymandias, King of Kings: Look upon my works, ye Mighty, and despair!" Nothing beside remains. Round the decay Of that colossal wreck, boundless and bare The lone and level sands stretch far away. -- Ozymandias, Percy Bysshe Shelley Shelley's immortal words ponder the fallibility of great empires, and how the natural forces of sand, silt and time can render meaningless great human accomplishments. Continually inhabited for over 5000 years, Egypt may be the world's greatest experiment in irrigated agriculture. The Nile River, the lifeblood of Egyptian civilisation, has been at the epicentre of Egypt's history throughout. For the vast majority of this history, the Nile was the dominant actor, with humans struggling to adjust to its whims. It is scarcely 30 years since the Aswan High Dam was completed, vigorously taming the Nile system under human stewardship. The tremendous import of this construction has been voluminously discussed, counterbalanced only by the dam's detractors. The one incontestable thing is that the dam exists, and barring a natural disaster of untold proportions, isn't going anywhere anytime soon. As such, the interesting challenge facing Egypt's hydraulic managers today lies not in debating the dam's pros and cons, but rather in maximising the opportunities, and limiting the threats, of the irrigation system's operations. In such a process, history is always a useful guide. For this is not the first time a civilisation has depended massively on its irrigation system; nor is it the first time that the successful management of such a system has been directly responsible for the continued viability of the civilisation as a whole. Over 4000 years ago, to the north of modern-day Basra, Iraq, the Sumerian civilisation at first flourished due to its irrigation prowess, and just as quickly disappeared entirely from view. Egypt, still in the infancy of its hydraulic experiment, may find useful lessons in the Sumerian experience. Historical sketch Mesopotamia, in Greek meaning "the land between the rivers," formed the southeast arm of civilisation's cradle, the Fertile Crescent. There, early Mesopotamian civilisations vied with Nile based civilisations for a variety of early human accomplishments: first written script, first urban and civil structures, first domesticated agriculture and irrigation. Mesopotamia's early civilisations of Sumer and Akkad, located in the southern section of Mesopotamia in the alluvial floodplain between the storied Tigris and Euphrates rivers, rose to a glorious zenith around 2500 BC, inventing, among other things, the wheel, the cuneiform script, and agricultural implements whose design remained standard until a few hundred years ago. Suddenly, however, around the 18th century BC, the civilisation disappeared. The seat of power moved north, where a civilisation based around Babylon rose to prominence. While the south was never abandoned, it never returned to prominence, and remains underdeveloped to this day. The reasons for Sumer's collapse, and the reason for its interest to an Egyptian audience, have to do with the management of its irrigated agriculture system. Agricultural practices The lower Mesopotamian valley is a generally flat, and Herodotus confirms that it used to be "one continuous forest of verdure." As the Nile to Egyptians, the history of Mesopotamian civilisation is inextricably intertwined with its two rivers, the Euphrates and the Tigris, which drain the rugged highlands of Turkish Anatolia and the Zagros Mountains of Iran. Civilisation clung to their banks and the rivers allowed the Sumerians to flourish as active traders at least as far away as Turkey, Iran and Syria The two rivers flow roughly parallel to one another throughout much of modern-day Iraq, joining in the south before their exit into the Persian Gulf to form the Shatt Al-Arab, an area extensively documented during Wilfrid Thesiger's travels among Iraq's Marsh Arabs in the 1940-50s. Aggregately, the two have considerable irrigation potential: for much of their course, the Euphrates travels 10 meters above the Tigris. This height difference between the rivers allowed for canals to be constructed, and irrigation channels to be dug. However, the soils have a low permeability, thus drainage is poor, and the water table is high. Hence the lower Mesopotamian plain has been prone to water logging throughout the ages. Irrigation was at the heart of Sumerian success, and irrigation allowed for the expansion of settlements beyond the immediate banks of the rivers, and a rapid increase in population. Sumerian agricultural achievements were impressive. One canal was 50 kilometres in length, displacing the amount of soil that would fill over 100 Olympic swimming pools, requiring the labour of over 1900 men working for 60 days, to complete. The typical Sumerian crop bundle, including cereals, pulses and fibre, served as the "founder crops" which provided the agricultural basis for food production around the world. Sumerian collapse Understanding what happened in Sumer requires a brief review of agricultural practices. Soil salinity refers to the amount of dissolved solids present in water. These solids -- primarily chemical compounds including chlorides -- occur naturally and are picked up by water during its travel over and through land. In irrigated systems, not all water directed is used by the crops in cultivation. The remaining water sits beneath the soil layer as ground water, becoming increasingly saline as it continues to interact with the ground around it. The application of irrigation water, without requisite drainage systems, will raise the level of this ground water so that either water rises up to inundate cropland, or that crops access saline groundwater through their roots. Once the right amount of water is obtained, getting rid of it eventually becomes as crucial as assuring its continued supply. While all naturally occurring water is to some degree saline, excessively saline water is harmful to crops. In bad cases of soil salinisation, the ground may become impenetrable to water altogether. Different crops have varying degrees of salt tolerance. As levels of suspended solids increase, certain crops may cease growing altogether. In Sumer, the extensive canal system developed by its powerful rulers allowed for the delivery of increased amounts of irrigation water. As a result of seepage, flooding and over-irrigation, a decisive rise in groundwater levels occurred. Saline groundwater was thus brought to within a few metres of the surface, poisoning crops drawing sustenance from it. As irrigation became less effective due to the build-up of soil salinity, wheat was gradually abandoned in favour of the more salt-tolerant barley. Yield rates per unit of land plummeted, until ultimately the lands were abandoned, caked white and eerily desolate. Creeping salinity is not a catastrophe like an earthquake or a flood, but it removes the ability of a state to be state-like, thus rendering it susceptible to more routine challenges to which it was previously impervious. Ultimately, the early Fertile Crescent civilisations had the misfortune to arise in an ecologically fragile environment. They committed ecological suicide by destroying their own resource base. Lessons for the future To conclude, based on these events, that Egypt is in danger of immanent societal collapse due to agricultural mismanagement is as absurd as it is alarmist. Technology, such as improved drainage techniques, fertilisers, and scientifically based crop rotation, has solved many of the challenges faced by the Sumerians. Furthermore, Egypt, blessed by better natural drainage, superior soil conditions, and sufficient water resources to flush saline build-up from its soils, is in nowhere near the fragile environmental position of the Sumerians. So are there any lessons we can draw from the Sumerian experience? To be sure, societies continue to confront, and fail to adapt to, the conditions faced by the Sumerians. The long-running human irrigation experiment has encountered salinity-related problems throughout the ages, and salinisation continues to affect irrigation projects today. Iraq's Marsh Arabs, the geographical descendants of ancient Sumer and Akkad, continue struggle with the same issues that affected their ancestors. The agricultural zone around the Aral Sea is currently undergoing an ecological disaster of the same proportions as Sumer. In what is perhaps the world's most advanced modern irrigation civilisation, California, well over half of its irrigated land is affected by soil salinity. It should be remembered that Sumer, a civilisation dominant in the region for hundreds of years, disappeared in a matter of decades. The study of the past provides useful insights for the present. After all, he who is ignorant of history is doomed to repeat it. It is easy for "technological optimism" -- a stubborn belief that relentless innovation and the construction of ever more ambitious engineering miracles will lead us on a continuing virtuous cycle of expanding production -- to overrule historical evidence. We believe that innovation immunises us from the dangers of salinity. But so did ancient societies. As Jared Diamond, author of the appropriately entitled book Collapse, puts it: "collapse has already befallen many societies that were at less risk than our societies are today." Ozymandias, the time-humbled monarch immortalised in Shelley's poem, is better known as Pharaoh Ramses II. * The writer is an American journalist residing in Cairo.
