"Nothing is more important to life than water, and no one knows water better than Sandra Postel. Replenish is a wise, sobering, but ultimately hopeful book." —Elizabeth Kolbert"Remarkable." —New York Times Book Review "Clear-eyed treatise...Postel makes her case eloquently." —Booklist, starred review"An informative, purposeful argument." —Kirkus We have disrupted the natural water cycle for centuries in an effort to control water for our own prosperity. Yet every year, recovery from droughts and floods costs billions of dollars, and we spend billions more on dams, diversions, levees, and other feats of engineering. These massive projects not only are risky financially and environmentally, they often threaten social and political stability. What if the answer was not further control of the water cycle, but repair and replenishment? Sandra Postel takes readers around the world to explore water projects that work with, rather than against, nature’s rhythms. In New Mexico, forest rehabilitation is safeguarding drinking water; along the Mississippi River, farmers are planting cover crops to reduce polluted runoff; and in China, “sponge cities” are capturing rainwater to curb urban flooding. Efforts like these will be essential as climate change disrupts both weather patterns and the models on which we base our infrastructure. We will be forced to adapt. The question is whether we will continue to fight the water cycle or recognize our place in it and take advantage of the inherent services nature offers. Water, Postel writes, is a gift, the source of life itself. How will we use this greatest of gifts?
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About the Author
Sandra Postel is director of the Global Water Policy Project and co-creator of Change the Course, the national water stewardship initiative awarded the 2017 US Water Prize for restoring billions of gallons of water to depleted rivers and wetlands. From 2009-2015, she served as Freshwater Fellow of the National Geographic Society. Postel is author of Pillar of Sand: Can the Irrigation Miracle Last? and Last Oasis: Facing Water Scarcity, the basis for a PBS documentary. Her work has appeared in Science, Natural History, and Best American Science and Nature Writing.
Read an Excerpt
Water Everywhere and Nowhere
In water that departs forever and forever returns, we experience eternity.
— Mary Oliver
As I wound my way up Poudre Canyon in northern Colorado, the river flowed toward the plains below, glistening in the midday sun. It ran easy and low, as it normally does as the autumn approaches, with the snowmelt long gone. I was struck by the canyon's beauty, but also by the blackened soils and charred tree trunks that marred the steep mountains all around. They were legacies, I realized, of the High Park Fire that had burned more than 135 square miles (350 square kilometers) of forest during the previous year's drought. It was September 7, 2013, and my family and I were heading to my niece's wedding. Tara and Eric had chosen a spectacular place for their nuptials — Sky Ranch, a high-mountain camp not far from the eastern fringe of Rocky Mountain National Park. As we escorted my elderly parents down the rocky path to their seats, I noticed threatening clouds moving in. They darkened as the preacher delivered his homily. Please cut it short and marry them, I thought to myself, before we all get drenched.
The rains held off just long enough. But that day's brief shower was a prelude to a deluge of biblical proportions that began four days later. A storm system stalled over the Front Range and in less than a week dumped nearly a year's worth of precipitation in some areas. The Poudre — short for Cache la Poudre — flooded bigger than it had since 1930. The torrential rains washed dead tree trunks down the hillsides into the raging river below. One canyon resident wrote that the blackened logs "looked like Tinker Toys amid the river's mad rush."
The threefold punch of drought, fire, and flood wreaked even worse havoc in neighboring mountain canyons, including that of the Big Thompson, a river renowned for the devastating flood of 1976. While that flood took 144 lives, it was relatively localized. This 2013 flood was vast, covering most of Colorado's Front Range and affecting not only high-elevation towns from Boulder to Estes Park — a number of which experienced a 1-in-500-year storm — but the heavily populated plains from Colorado Springs north to Fort Collins. Though by no means the deadliest, with eight lives lost, it became one of the costliest flood events in Colorado's history. It triggered 1,300 landslides, damaged some 19,000 homes and commercial buildings, required the evacuation of more than 18,000 people, damaged 27 state dams (and completely took out a handful of "lowhazard" dams), and damaged or destroyed 50 bridges and 485 miles (780 kilometers) of roads. Losses were estimated to total some $3 billion.
Floods of this magnitude, while rare overall, are completely unexpected in Colorado in the very late summer. In river systems fed by melting snows, the biggest floods normally occur in the spring, as temperatures warm and snowmelt pours into headwater streams and the rivers they feed. Intense summer thunderstorms occasionally create localized flooding in July or August, but by September rivers are typically running low, just as the Poudre was when I drove up the canyon.
Brad Udall, a water and climate expert at the University of Colorado in Boulder, whose house sits just 30 feet (9 meters) from a creek that's normally dry in September, saw the creek turn into a raging stream. "This was a totally new type of event," Udall told National Geographic, "an early- fall, widespread event during one of the driest months of the year."
So often these days water seems to be nowhere and everywhere all at once. The wild weather of 2015 became almost legendary, even before the year was over. With raging floods in Latin America, the US Midwest, and the United Kingdom, and withering droughts in eastern and southern Africa, most of California and southeastern Brazil, terms such as anomalous, historic, and epic dominated the weather lexicon. US scientists determined that during one rare October rainstorm 17 streams in the US state of South Carolina broke records for peak flow. According to the United Nations, two years of drought left nearly 1 million African children suffering from acute malnutrition, and millions more at risk from hunger, water shortages, and disease.
Although the weather phenomenon known as El Niño became the go-to explanation for the global turmoil that year, this periodic event was not fully to blame. The El Niño came atop long-term warming trends that are fundamentally altering the movement of water across the planet. The earth was hotter in 2016 than since record keeping began in 1880. The previous record was 2015, which itself had beaten the previous record of 2014 by a considerable margin. For the contiguous United States, 2016 marked the twentieth consecutive year that the annual average temperature was higher than the twentieth-century average.
As air warms, it expands, which allows it to hold more moisture. This, in turn, increases evaporation and precipitation, which generally makes dry areas drier and wet areas wetter. If disasters related to droughts, floods, and other extreme weather seem more common globally, it's because they are: according to a United Nations study, between 2005 and 2014, an average of 335 weather-related disasters occurred per year, nearly twice the level recorded from 1985 to 1995.
If we don't adapt to these new circumstances, a future of more turmoil is bound to unfold. The 6,457 floods, storms, droughts, heat waves, and other weather-related events that occurred over the last two decades caused 90 percent of disasters during that period. Those disasters claimed more than 600,000 lives and cost more than $1.9 trillion, according to the UN study. The countries hit with the highest number of disasters over the twenty-year period were the United States, with 472, and China, with 441, followed by India, the Philippines, and Indonesia.
Meanwhile, extreme weather is also affecting our food supply. A team of Canadian and UK scientists found that from 1964 to 2007 droughts and heat waves had each slashed the production of cereals by about 10 percent — and by 20 percent in the more-developed countries. Altogether, the loss was estimated at 3 billion tons.
Leaders in business and government are beginning to take notice. More than 90 percent of companies in the S&P Global 100 Index see extreme weather and climate change impacts as current or future risks to their business. At its annual gathering in Davos, Switzerland, in 2016, the World Economic Forum — which counts among its members heads of state, chief executive officers, and civic leaders — declared water crises to be the top global risk to society over the next decade. Next on the list were the failure to mitigate and adapt to climate change, extreme weather events, food crises, and profound social instability. All five threats are intimately connected to water. Guarding against each requires a new understanding of our relationship to freshwater — and a new way of thinking about how we use, manage, and value it.
Water is unlike any other substance. It is always on the move — falling, flowing, swirling, infiltrating, melting, condensing, evaporating — and all the while knitting the vast web of life together. Through its endless circulation, water connects us across space and time to all that has come before and all that is yet to be. Our morning coffee might contain molecules the dinosaurs drank.
This profound connection is created by one of the most mysterious and underappreciated of Earth's natural phenomena: the water cycle. Those fifth-grade textbook diagrams never quite do it justice. We see the labels of water stocks and flows and the arrows signaling movement from sea to air to land, but never really grasp the magic wrought by two atoms of hydrogen uniquely bonded to one of oxygen. Water is the only substance that can naturally exist as a liquid, gas, or solid at normal Earth temperatures.
With hydrogen from the primordial Big Bang and oxygen from early stardust, water was born. Infant Earth, hot as Hades, was enveloped in water vapor, but it took a billion or more years of cooling before that vapor could condense and fall to the young planet's surface as rain. Liquid water has wetted Earth for at least three billion years. Today, that stock of water is finite, except perhaps for minute additions from so-called cosmic snowballs — small comets made of water that smash into the earth.
This finite supply circulates over vastly different scales of time and space. Some water molecules get trapped ultra deep within the earth, remain there for millennia, and then suddenly burst into the atmosphere through an erupting volcano. Others reside close to the earth's surface, changing back and forth between liquid and vapor as they evaporate from a lake, condense into a cloud, and fall as rain to join a river as it flows to the sea. From there, they evaporate again, and the cycle continues. Still other molecules remain trapped for centuries in glacial ice until they melt to replenish a mountain meadow and the groundwater below. "Whenever you eat an apple or drink a glass of wine," writes astrophysicist and author Robert Kandel, "you are absorbing water that has cycled through the atmosphere thousands of times since you were born. But you are also absorbing some water molecules that have only been out in the open air for a few days or weeks, after tens or hundreds of millions of years beneath the Earth's crust."
Almost all the water on Earth — 97.5 percent — resides in the ocean and is too salty to drink or to irrigate most crops. Of the remainder, about two-thirds is locked up in glaciers and ice caps. Only a tiny share of Earth's water — less than one one-hundredth of one percent — is both fresh and continuously renewed by the solar-powered global water cycle.
Each year, the sun's energy lifts nearly 500,000 cubic kilometers (132 quadrillion gallons) of water from the earth's surface — 86 percent from the oceans and 14 percent from the land. An equal amount falls back to Earth as rain, sleet, or snow, but, fortunately for us, not in the same proportions. Wind and weather transfer about 9 percent of the vapor lifted from the sea over to the land. This net addition of about 40,000 cubic kilometers combines with the 70,000 lifted from the land and its vegetation each year to create our total annual renewable water supply: 110,000 cubic kilometers (29 quadrillion gallons). The 40,000 cubic kilometers distilled and transferred from the oceans to the land makes its way back to the sea through rivers and shallow groundwater — what hydrologists call "runoff" — completing the global cycle and balancing nature's water accounts.
That runoff is what we tap to irrigate crops, supply water to our homes and businesses, manufacture all of our material goods, and run turbines to generate electricity. It is also the water supply for all the fish, birds, insects, and wildlife that depend on rivers, streams, and wetlands for their habitats. Although the water cycle delivers that runoff each year, water is not always where we need it when we need it. Nature's water deliveries are often poorly matched with where people live or farmers find it best to grow crops. Today, for example, China is home to 19 percent of the world's population, but only 7 percent of global runoff.
Although we speak of a global cycle, water circulates at many scales. Consider, for example, the tomato plant in your garden. Through its roots, it takes up moisture from the soil supplied by rain (and perhaps your extra watering), keeps some of it to fill its growing stems and leaves, and releases the rest in the form of vapor back to the atmosphere through openings in its leaves. Once aloft it may condense and fall again as rain. Similarly with the human body, 60 percent of which is water. We take water in through food and drink, rehydrate, and then release water back to the environment either in liquid form through our urine or in vapor form through our breath and the evaporation of our sweat. All terrestrial plant and animal life participates in the cycling of water.
During the ten thousand years since Homo sapiens opted for settled agriculture over its earlier hunter-gatherer existence, human activities have increasingly altered local, regional, and, more recently, global water cycles. Among the earliest people to do so on a substantial scale were the Sumerians, who migrated out of the Mesopotamian highlands some 5,500 years ago and settled in the lowland plains of the Fertile Crescent, in what is now southern Iraq. Their new locale was sunnier and, in that way, better for growing crops, but it lacked rainfall at critical times during the growing season. So the Sumerians constructed canals to transport water from the Euphrates River to their fields, and as a result became the first society in the world based on irrigation.
Little did the Sumerians know, however, that this alteration of water's natural journey would be their undoing. The reason was not the water war 4,500 years ago between the two Mesopotamian city-states of Lagash and Umma. It was salt. The river water helped their wheat to grow, but once it transpired through the plants and evaporated from their fields, it left its natural salts behind — salts the Euphrates River would have otherwise carried to the Persian Gulf. As the salts accumulated in the soil, their wheat yields declined. The Sumerian farmers tried growing barley, a more salt-tolerant crop, but eventually those yields declined as well. When the land could no longer produce enough food, the people of Sumer packed up and headed north, leaving a salty wasteland behind.
Since those early experiments of hydraulic manipulation, the scale and variety of human interventions in water's natural flow through the landscape have grown tremendously. By the second century BC, the Han dynasty in China was building earthen dams 30 meters (98 feet) high. But it was really in the mid-nineteenth century with advances in hydraulics, fluid mechanics, civil engineering, and other applied sciences that the construction of large-scale water infrastructure took off. In 1885, the British began remaking the Indus River Valley in colonial India into a massive irrigation network for the production of wheat. Although plagued by the scourge of soil salinity, just as the Sumerian lands had been long before, the Indus scheme eventually became the world's largest contiguous irrigation network, spanning 14 million hectares (35 million acres), an area a bit larger than the country of Costa Rica.
Late nineteenth- and early twentieth-century scientific advances coincided with an evolving utilitarian philosophy that nature could be fundamentally transformed. Samuel P. Hays, in his 1959 book Conservation and the Gospel of Efficiency, described how, just after 1900, large-scale river development "suddenly captured the imagination" of conservation leaders. They grasped that "flood waters, now wasted, could, if harnessed, aid navigation, produce electric energy, and provide water for irrigation and industrial use." In 1908 Winston Churchill stood on the shore of Africa's Lake Victoria, watching its waters spill over Owen Falls into the White Nile, and later reflected on the experience: "So much power running to waste ... cannot but vex and stimulate the imagination. And what fun to make the immemorial Nile begin its journey by diving into a turbine."
In that same vein, geologist and inventor William J. McGee, who held prominent US government and scientific positions during the late nineteenth and early twentieth centuries, wrote with prescience in 1909 that "the conquest of nature is now extending to the waters on, above, and beneath the surface. The conquest will not be complete until these waters are brought under complete control."
These aspirations came to fruition in 1935 with the completion of the architecturally stunning Hoover Dam (originally named Boulder Dam) on the Colorado River in the southwestern United States. Hoover gave rise to the age of super dams and a whole new degree of control over water. US engineers actively exported their dam-building knowledge and expertise to other countries, and within decades arid lands around the world were open for business. With access to water, cities and farms spread like mushrooms in damp woods. Large reservoirs and tall levees offered a degree of flood control that encouraged farms and cities to locate in river floodplains, where they had access to rich soils and shipping corridors. Turbines affixed to big dams churned out electricity that propelled economies forward. In a speech in July 1954, India's prime minister, Jawaharlal Nehru, referred to dams as "the temples of modern India."
The construction of these "modern temples" proceeded at a rapid clip. During the last half of the twentieth century, the nations of the world built an average of two large dams a day. As the twenty-first century dawned, some 45,000 large dams — those 15 meters (49 feet) or higher — blocked the world's rivers. China was also proceeding with the world's biggest river diversion scheme to transfer water more than 1,000 kilometers (600 miles) from the Yangtze River in the south to the drier north. Farmers around the globe were pumping vast quantities of groundwater to the surface to irrigate their fields and boost their harvests. By then, hydropower accounted for 19 percent of global electricity use. Populations were growing fastest in some of the world's driest places.
Excerpted from "Replenish"
Copyright © 2017 Sandra Postel.
Excerpted by permission of ISLAND PRESS.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents
Chapter 1. Water Everywhere and Nowhere Chapter 2. Back to Life Chapter 3. Put Watersheds to Work Chapter 4. Make Room for Floods Chapter 5. Bank It for a Dry Day Chapter 6. Fill the Earth Chapter 7. Conserve in the City Chapter 8. Clean It Up Chapter 9. Close the Loop Chapter 10. Let It Flow Chapter 11. Rescue Desert Rivers Chapter 12. Share Acknowledgments Notes Bibliography Index