Water Resources

By Shimon C. Anisfeld

ISLAND PRESS

Copyright © 2010 Shimon C. Anisfeld
All rights reserved.
ISBN: 978-1-59726-495-2

Contents

Preface,
Chapter 1. Past, Present, and Future: Introduction to the Water Crisis,
Chapter 2. Quantity and Quality: Introduction to Water Resource Science,
Chapter 3. Supply and Demand: Water Availability and Water Use,
Chapter 4. Water, Water, Everywhere: Dealing with Floods,
Chapter 5. Nor Any Drop to Drink: Water Scarcity,
Chapter 6. The End of Stationarity: Water in an Era of Global Change,
Chapter 7. Soft and Hard: Technologies for Sustainable Water Management,
Chapter 8. Humans and Ecosystems: Finding the Right Balance,
Chapter 9. Overconsumption and Underconsumption: Water for Households and Health,
Chapter 10. Crops and Drops: Getting More from Less in Agricultural Water Use,
Chapter 11. Growth and Sustainability: Using Water More Wisely in Industry,
Chapter 12. Basic Need and Economic Good: The Contested Role of Economics in Water,
Chapter 13. Conflict and Cooperation: Transboundary and Intersectoral Water Management,
Chapter 14. Conclusion: The Imperative of Better Management,
Discussion Questions,
Glossary,
References,
Recommended Readings,
Index,

CHAPTER 1

Past, Present, and Future: Introduction to the Water Crisis

Take a moment to imagine water, to bring a picture of this vital substance to your mind's eye.

What do you think of? A favorite lake or river? A glass of drinking water? A refreshing shower? An irrigation sprinkler? A baptismal font?

People and water are deeply interlinked. We humans are mostly water, as is the surface of the planet we live on. We use water in so many ways: drinking; cleaning ourselves and our belongings; growing our food; making the products we use; producing energy; enjoying ourselves while swimming or boating; fishing; transporting people and goods; sustaining our spirits. Equally important to our survival, but less obvious, is the fact that water plays a critical role in maintaining the health of the earth by controlling the planet's heat and energy balances, cycling nutrients and other elements, allowing the growth of the plants and algae on which all life depends, and maintaining the biodiversity of aquatic and terrestrial ecosystems.

This book is an introduction to water resources, in which we explore the many interactions between people and water. It emphasizes two contrasting—but complementary—ideas: (1) we are facing serious water problems, and (2) there is much that we can do to manage this resource better and alleviate those problems. This chapter provides a brief history of past water management, a summary of the present crisis, and some thoughts on possible paths toward a better future.

1.1. The Past: A Brief History of Water Resource Management

Humans have always needed water, and early civilizations developed where water sources were available to support their populations. Over time, different regions developed their own approaches to managing water, displaying a rich diversity of technologies. A few examples: The ancient Egyptians were heavily dependent on the Nile for irrigation water, which they obtained both through natural flooding and through active water management such as the digging of irrigation canals and the utilization of water-lifting devices such as the shadouf. The Egyptians also developed a system for monitoring and recording river water levels. In Persia, tens of thousands of gently sloping underground tunnels called qanats were dug to deliver groundwater to cities and fields; similar technologies with different names have been used around the world (karez in Afghanistan, laoumia in Cyprus, surangam in India). The Romans built pipelines and large raised aqueducts to transport water, and constructed buried sewer pipes to remove wastewater. The Chinese constructed irrigation canals to bring water from rivers to fields, dug the 1600-km-long Grand Canal to transport goods and people, and built levees along the Huang He (Yellow River) to protect land from flooding. The Spanish developed a system of irrigation canals called acequias, which they later introduced to the areas that they colonized in the New World. In England and elsewhere, water was used to power mills, often by impounding water behind a small dam.

Along with these technologies came cultures and governance systems for managing water. The historian Karl Wittfogel famously argued that water had a strong influence on the development of despotic civilizations ("hydraulic empires") in the Middle East and Asia, due to the need to harness large amounts of manpower to build and maintain water delivery systems in arid regions with large rivers (Wittfogel 1957). Wittfogel's thesis is now considered overly simplistic, but it points to the ways that water—as arguably the most important natural resource of all—can influence the development of civilizations.

The Twentieth Century

The twentieth century saw global population increase dramatically from about 1.6 billion to 6.1 billion. This population explosion, together with the development of new technologies, led to significant changes in water management. In turn, these changes in water management were crucial in allowing the expansion in population, which would not have been possible without new water supplies for cities and for agriculture.

Water management in the twentieth century was dominated by what has been referred to as the "hard path." Three technologies played crucial roles in defining this path.

Dams

For centuries, small dams have powered mills and impounded water for storage and delivery. But the twentieth century saw an explosion in dam-building, especially of large dams—those over 15 meters high—and major dams—those over 150 meters high. The real era of dam-building began in the mid-twentieth century, first in the United States and then in other countries. By the year 2000, there were approximately 48,000 large dams worldwide, an astonishing number. Although North America and Europe have largely stopped building dams, dam construction in Asia continues apace, especially in China and India. China now has about half of all the large dams in the world (WCD 2000).

Dams are built for several purposes:

• Water supply and irrigation: Dams allow for the delivery of water to urban ("water supply") and agricultural users, through two mechanisms. First, dams simplify the process of capturing and delivering water from a river by creating an impoundment from which to draw water and by increasing the elevation of the water so that it can be delivered more easily by gravity. Second, dams capture water during wet periods and store it for delivery during dry periods. This is particularly important in seasonal or drought-prone climates.

• Flood control: Dams can capture large floods and release them slowly to minimize flooding damage downstream.

• Hydropower: The power of falling water can be used to run watermills or, as is done today, drive turbines that generate electricity.

• Navigation: Dams convert flowing, shallow water to still, deep water, which can allow ships and barges to more easily move up and down river systems.

• Recreation: A secondary purpose for many large dams is water-based recreation on the reservoir that develops behind the...