The 25 August 2006 issue of Science Magazine included a 23 page "Special Section" titled Freshwater Resources.
It addresses issues of fresh water world wide. The following quotations and illustartion are taken from this issue of Science.
A Thirsty World
by Jake Yeston, Robert Coontz, Jesse Smith, Caroline Ash
"The search for fresh water--to drink, to bathe in, to irrigate crops--is a problem as old as civilization. Across the ages,
cities have thrived where the supply is abundant and collapsed in the face of drought. Remarkably, despite the technological
progress characterizing the modern era and the fact that most of Earth's surface is covered by oceans, the availability of fresh
water remains a pressing concern throughout the world."
Global Hydrological Cycles and World Water Resources
by Taikan Oki1,2,3* and Shinjiro Kanae1,4*
"Water is a naturally circulating resource that is constantly recharged. Therefore, even though the stocks of water in natural
and artificial reservoirs are helpful to increase the available water resources for human society, the flow of water should be
the main focus in water resources assessments. The climate system puts an upper limit on the circulation rate of available
renewable freshwater resources (RFWR). Although current global withdrawals are well below the upper limit, more than two
billion people live in highly water-stressed areas because of the uneven distribution of RFWR in time and space. Climate
change is expected to accelerate water cycles and thereby increase the available RFWR. This would slow down the increase of
people living under water stress; however, changes in seasonal patterns and increasing probability of extreme events may
offset this effect. Reducing current vulnerability will be the first step to prepare for such anticipated changes."
Desalination Freshens Up -
Robert F. Service
"Cheaper materials, more efficient equipment, and some promising new approaches could make large-scale extraction of clean
water a major force in the battle against global thirst.
"Efforts to provide clean, fresh water for the world's inhabitants seem to be moving in the wrong direction. According to the
World Health Organization, 1 billion people do not have access to clean, piped water. A World Resources Institute analysis
adds that 2.3 billion people--41% of Earth's population--live in water-stressed areas, a number expected to climb to 3.5
billion by 2025. To make matters worse, global population is rising by 80 million a year, and with it the demand for new
sources of fresh water.
"Such concerns have made desalination--the process of removing salts and suspended solids from brackish water and
seawater--a fast-growing alternative. According to a 2004 report by the U.S. National Research Council, more than 15,000
desalination plants now operate in more than 125 countries, with a total capacity of turning out 32.4 million cubic meters
(m3) of water a day, about one-quarter of the amount consumed by U.S. communities each year. With numerous areas around the
globe facing long-term severe water shortages, "I don't see [the demand for desalination] slowing down any," says Michelle
Chapman, a physical scientist at the U.S. Bureau of Reclamation in Denver, Colorado, and co-chair of a desalination research
program funded by the U.S. Office of Naval Research."
How Will Water Use Change in the Future?
"The global population will certainly grow, at least for several decades, and water demand will increase as a result.
Water demand per person will most likely also increase due to economic growth. For example, an expected growth of meat
consumption will increase the water demand for fodder production.
"The ultimate objectives of future-oriented world water resource assessments are to show the international community what
will happen if we continue to manage our water resources as we do today and to indicate what actions may be needed to prevent
undesirable outcomes. In that sense, studies of future world water resources are successful if their predictions based on
business-as-usual are proven wrong."
What Effects Will Climate Change Have on RFWR?
"The effect of global climate change on hydrological cycles is still uncertain, but higher temperatures will turn
some part of snowfall into rainfall, the snowmelt season will be earlier, and, as a result, the timing and volume of
spring flood will change substantially. Nearly half of the world's population depends on groundwater sources for
drinking water supply and for other uses. Sea level rise will cause saline water intrusion into groundwater aquifers
near the coasts and will decrease the available groundwater resources. On the water demand side, changes in the seasonal
pattern have not been estimated globally, and a comprehensive description of groundwater withdrawal in the world is largely
Illustration from Science Magazine
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