PILLAR OF SAND

CAN THE IRRIGATION MIRACLE LAST?

SANDRA POSTEL

NORTON/WORLDWATCH BOOKS                  1999

Preface by Sandra Pastel March 1999

• The key challenge has been clear: How can we meet growing human needs for water without destroying the health of rives, lakes, and other aquatic systems that we depend on and that provide so many benefits?
• My previous book, Last Oasis, attempted to lay out the scale of the global water challenge in its many dimensions and showed the large and largely untapped potential of conservation and efficiency to help move us toward a more sustainable relationship with fresh water.
• With Pillar of Sand, I zero in on the most difficult challenge presented by water scarcity – growing enough food for our future population in a sustainable manner.
• Early chapters look at the major ancient irrigation-based civilizations and the rise of our modern irrigation society. The last third of the book sketches a blueprint for a more productive, ecologically sound, and potentially lasting form of irrigated agriculture.
• Despite the daunting nature of the global water challenge, I remain optimistic about our ability to meet it. I have seen firsthand many promising projects and initiatives.
• So far, our degree of response to the challenge pales in comparison to its scale. Success will involve reshaping many facets of society – from our individual consumption patterns to national economic activities and regional politics.
• My hope is that Pillar of Sand will provide inspiration to take up this challenge, as well as some useful ideas for successfully meeting it.

Chapter 1: New Light on an Old Debate

• The story of controlling water for agriculture begins around 4000 B.C. in the plains between the Tigris and Euphrates Rivers, the heart of what would later be called the Fertile Crescent, in present-day Iraq.
• Large food surpluses appeared, freeing a portion of society to pursue other activities. The inventions and advances of this nonfarm class spanned metallurgy, weaving, ceramics, specialized crafts, writing, architecture, and mathematics.
• Populations increased in size and density, producing the first true cities. Irrigation unleashed a profound transformation in human development, and created a new foundation from which civilizations sprung and blossomed.
• Irrigation brought with it the threat of soil degradation – in particular, the build up of salts. In dry climates, evaporation of water from the upper layers of soil can leave behind in the root zone a layer of salt that is damaging to crops.
• In 1800, global irrigated area totaled just 8 million hectares. Today the irrigation base is 30 times larger. We derive 40% of our food from irrigated land. Many agricultural experts are counting on such lands to provide the bulk of the additional food that will be required over the next three decades.
• Groundwater is being pumped faster than nature is recharging it in many of the world’s most important food-producing regions. Worldwide, the amount of irrigated land per person has been declining for nearly two decades because of rising economic, social, and environmental costs of new water projects.
• Water scarcity is now the single biggest threat to global food production. Poverty levels raise doubts about the ability of some nations to import enough grain to fill their emerging food gaps. Global food models largely ignore water constraints, and as a result they present an overly optimistic picture of future food availability.
• Until recent decades, additions to the world’s food supply came from three major food sources – rangeland, cropland, and fisheries. But two of these three have already hit or exceeded their natural limits.
• Each year, an estimated 10 million hectares are lost to erosion, other forms of degradation, or conversion to factories, houses, shopping malls, or other uses. Net cropland expansion could well be close to zero.
• The principal remaining agricultural frontier is land productivity – coaxing more production from each parcel of cropland.
• It takes about 1,000 tons of water to grow one ton of wheat. Worldwide, crops currently get about 70% of their water directly from rainfall and 30% from irrigation.
• Reaching the food production levels needed in 2025 could require a water volume equivalent to the annual flow of 24 Nile Rivers or 110 Colorado Rivers. As later chapters will show, supplying this much additional water will be difficult. The modern irrigation age is running out of steam.
• Many of the insidious threats that undermined ancient irrigation civilizations – including salt, silt, neglect of infrastructure, regional conflict, and unexpected climatic change – are rearing their ugly heads.
• We need to double water productivity – get twice as much benefit from each liter of water – if we are to have any hope of fulfilling the water requirements of 8 billion people and protecting the natural ecosystems on which economies and life itself depend.
• There is no such thing as a post-agricultural society. To act as if there were is a recipe for societal collapse. The overriding lessons from history is that most irrigation-based civilizations fail. Will ours be any different?

Chapter 2: History Speaks

• At least a half-dozen major irrigation-based civilizations arose between 2,000 and 6,000 years ago. Several of them, including the Sumerians, Babylonians, and Assyrians, thrived in the basin of the Tigris and Euphrates Rivers of present-day Iraq.
• The reduced volume of the Euphrates’s flow caused the river to drop more of its silt, clogging irrigation canals. Reduced irrigation capacities resulted in falling food supplies, famine and social disintegration, bringing the empire to its final downfall.
• Salt’s ability to poison the soil of irrigated lands has posed a constant risk in many irrigation-dependent societies throughout history, and remains a threat to our agricultural foundation today. Water evaporates, leaving the salts behind.
• By the 16^th century, the Fertile Crescent of Mesopotamia, from which human civilization had sprung and reached unprecedented heights, was little more than a salty wasteland. These societies had given the world writing, mathematics, magnificent palaces, and unparalleled feats of engineering. But they had not created a system of agriculture that could sustain their people.

Chapter 3: Irrigation’s Modern Era

• In 1800, just before the dawn of the modern irrigation age, world irrigated area totaled 8 million hectares, an area about the size of Austria.
• By 1995, world irrigated area was just over 255 million hectares – an area more than two-and-a-half times the size of Egypt.
• Many nations rely on irrigated land for more than half of their domestic food production. Some 40% of the world’s food now comes from the 17% of cropland that is irrigated.
• China suffers from a severe imbalance between its population size and its water endowment: the nation has 21% of the world’s people but only 7% of its renewable fresh water. Even worse, that water is distributed very unevenly in time – not when it is needed –  and geographically – not where it is needed.
• Between 1970 and 1982, global irrigated area grew at an average rate of 2% a year. Between 1982 and 1994, this rate dropped to an annual average of 1.3%. Over the next 25 years, the global irrigation base is unlikely to grow faster than 0.6%, and even this may turn out to be optimistic.
• Per capita irrigated area peaked in 1978 and has fallen 5% since then. By 2020, per capita irrigated area will likely be 17-28% below the 1978 peak. Irrigation has simply begun to reach diminishing returns.

Chapter 4: Running Out

• On February 7, 1997 the Yellow River, the cradle of China’s civilization, stopped flowing for a record 226 days. The previous two years had each set records as well – 133 days in 1996 and 122 days in 1995.
• Many of the world’s most important food-producing regions are simply running out of water for irrigation. Farmers are pumping groundwater faster than nature is replenishing it, causing a steady drop in water tables.
• Climate change has the potential to greatly alter the ‘game’ of agriculture, but scientists do not know how, when or under what conditions this wild card will be played. Rainfall patterns will shift, river flows will change, hurricanes and monsoons are likely to intensify, and sea level will rise from thermal expansion of the oceans and the melting of mountain glaciers and polar ice caps.
• Three things are certain: The future will not be a simple extrapolation of the past; For some period of time, reservoir and irrigation systems are likely to be poorly matched to altered rainfall and runoff patterns; If and when the needed adjustments are made, they will be costly.

Chapter 5: A Faustian Bargain

• Our modern society may have inadvertently struck a Faustian bargain with nature. In return for transforming deserts into fertile fields and redirecting rivers to suit human needs, nature is extracting a price in myriad forms. Among the most threatening is the scourge of salt.
• All it takes is a look at southern Iraq, site of the earliest Mesopotamian civilizations, to be reminded that where salt claims a victory, it can be a very long-lasting one.
• The bottom line is that there is no simple fix to the salt problem. By growing crops more tolerant of salt in salty soils, farmers can lessen the damage salinity causes to crop production, but they cannot avoid yield reductions entirely.

Chapter 8: The Productivity Frontier

• Along with technologies like drip that deliver water more effectively to crops, improved management practices can help farmers reduce their water demands while maintaining or increasing crop yields.
• Among the most exciting and potentially beneficial is the use of weather monitoring and satellite technologies to help farmers know when their crops actually need water.
• Between 1951 and 1985, Israel expanded its irrigated area fivefold with only a threefold increase in water use. Output per cubic meter nearly tripled and the value of output (in real terms) jumped 10-fold.
• Israel is the only nation that appears to have done what the world needs to do over the next 30-40 years – double water productivity in agriculture.
• About 100 million of the world’s 255 million hectares of irrigated land are planted in rice, the preferred staple for about half of the human population. Finding ways of growing rice with less water is critical to sustaining the harvest of this important crop, much less expanding it.
• Agronomic options for getting ‘more crop per drop’ are inherently limited. Many grains native to Africa are naturally hardier, more heat- and drought-tolerant, and need less irrigation water than modern varieties do.
• These traditional crops have lower average yields but may have a greater role to play as drought, water scarcity, and increasing competition for water further impinge on agriculture.
• The last set of options for improving water productivity is the most obvious – using water more than once.

Chapter 9: Thinking Big About Small-Scale Irrigation

• Like trickle-down economics, trickle down food security does not work well for the very poor. Globally the grain harvest is more than adequate to feed everyone a sufficient diet, yet one out of seven people in the world does not get enough to eat.
• The production and trade of more ‘surplus’ food will not solve their problems of hunger because many of them are too poor to buy that food, even at today’s historically low prices.
• The surest and most direct way of reducing hunger among the rural poor is to raise their productive capacities directly. Access to irrigation is one of the surest ways of boosting small-farm productivity.
• Spreading the benefits of irrigation to small farmers in Sub-Saharan Africa is as critical as in South Asia, and even more challenging. Deep pockets of poverty persist in this region.
• In Malawi, Tanzania, Zambia, and many other sub-Saharan countries, small-scale farmers account for 80-85% of the farming population. Equipment often costs 2-10 times more than in Asia. Many farmers lack secure tenure on their land and lack access to credit. Poor transportation and marketing facilities often make it difficult to profit from agricultural investments.
• Small-scale irrigation schemes have the potential to make a huge contribution in the region.
• In Israel, researchers are reviving techniques practiced by the Nabateans. A 1-hectare farm is watered by a 250-hectare catchment.
• In many watersheds, constructing a small dam across a gully can trap large amounts of runoff, which can either be channeled directly to a field, stored for later use, or allowed to percolate through the soil to recharge the underlying groundwater.

Chapter 11: Listening to Ozymandias

• History tells us that most irrigation-based societies fail. Some 40% of our food comes from irrigated land, and we are betting on that share to increase in the decades ahead.
• The signs of trouble are surfacing with unprecedented speed. 60% of our irrigation base is less than 50 years old, yet threats to the continued productivity of much of this land are already apparent.
• A tenth of the world’s current grain harvest is propped up by unsustainable water use. Irrigation’s land and water base are rapidly being eroded by salinization of soils, siltation of reservoirs, and the siphoning off of irrigation water to supply burgeoning cities.
• Grave as these developments are, political leaders have scarcely taken notice of them – a situation ominously reminiscent of that in ancient Mesopotamia.
• With an expanding world population, farmers, scientists, and engineers are called upon to do again what they did during the last 50 years – but this time with a greatly depleted larder of natural resources. Water scarcity, in particular, will make a second round of success extremely difficult.
• Over the next quarter-century we will see more than a six-fold increase in the number of people living in water-stressed countries. Competition for water will spread across borders through the global grain trade as more countries attempt to import enough grain to fill their food gaps.
• Whether food exporters will be able to satisfy demands is only half the issue. Equally important is whether importers can afford to buy the grain they need.
• Climate change on the scale that scientists are projecting for the next century adds a whole new dimension to the food and water challenge. History shows that climate wild cards can overwhelm a seemingly advanced society’s ability to cope.
• Any one of the stresses evident today would seriously challenge irrigated agriculture’s future productivity. But these stresses are evolving simultaneously, which magnifies the constraints on future food production and heightens the risk that rising food prices or larger pockets of hunger will destabilize civil societies.
• Even small changes in individual consumption – such as dietary choices – can have a large collective impact on the environment. Numerous opportunities exist to improve water productivity in homes, offices, commercial enterprises, and manufacturing facilities.
• Time, however, is of the essence. If we fail to make a timely transition, we will see – just as our predecessors in the Fertile Crescent did – that we do indeed rest on a pillar of sand.