Global Stressors of Water Cycle 08

Global Stressors of Water Cycle 08 - Global Stressors on...

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Global Stressors on Water Quality and Quantity Growing population and wealth will impact sustain- ability, technology selection, and governance strategies related to water issues. JULIE BETH ZIMMERMAN YALE UNIVERSITY JAMES R. MIHELCIC MICHIGAN TECHNOLOGICAL UNIVERSITY JAMES SMITH UNIVERSITY OF VIRGINIA This inequality is especially critical for Asia, which has 60% of the world’s population but only 36% of the world’s water. Water quality in terms of pollutant loading also is not distributed equally and is related to the type of use and a country’s level of develop- ment (Figure 2). Developing countries often have less capacity to improve water quality and depend on lower-quality water for a variety of uses, includ- ing drinking water. To capture an overall picture of a nation’s water use, researchers calculate the national water foot- print; this represents the total volume of freshwater used to produce the goods and services consumed by a population and the impact of globalization by F or more than a decade, the scientific com- munity as well as nongovernmental orga- nizations have sought to raise an alarm concerning the unsustainable use of the planet’s available water resources ( 1 ). Rising world populations and consumption are inexorably increasing human demand for domestic, industrial, and agricultural water. Population and wealth along with other global stressors will have a direct and significant impact on the sustainability goals, tech- nology selection, and governance strategies that are related to water quality and quantity. On a global basis, ~70% of freshwater is currently used for crop irrigation, ~20% for industrial purpos- es, and ~10% for domestic purposes ( 2 ). However, wa- ter use varies dramatically from one part of the world to another. Egypt, for example, uses 98% of its water for irrigation, leaving only ~27 L/capita-day for do- mestic use. In contrast, the U.S. uses 40% of its water for irrigation, and domestic water use exceeds 410 L/ capita-day. In refugee camps in Africa and Asia, resi- dents may receive only 15 L/capita-day for both con- sumption and hygiene. For comparison, the World Health Organization defines reasonable access as the availability of at least 20 L/capita-day from a source within 1 km of the user’s dwelling ( 3 ). Although the quantity of water used varies by region, water is not distributed equally (Figure 1). © 2008 American Chemical Society ISTOCKPHOTO JUNE 15, 2008 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 4247
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accounting for water across the life cycle of imports and exports ( 5 ). Water use is measured in terms of water volumes consumed (evaporated) or pollut- ed per unit of time. In this way, it is similar to the concept of “virtual” water, because it accounts for water use associated with consuming agricultural and industrial imports. For the period of 1997–2001, the global water footprint was 1243 m 3 /capita-year, 16% of which was the external water footprint (as- sociated with importing goods and services for consumption; 5 ). However, some countries have ex-
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This note was uploaded on 10/16/2010 for the course ESPM C12 taught by Professor Garrisonsposito during the Spring '10 term at Berkeley.

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Global Stressors of Water Cycle 08 - Global Stressors on...

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