Twenty-five years, environmentalist Marc Reisner published Cadillac desert: the American West and its disappearance, water that predicts that water in the West would be impossible to support the growing demand of cities, agriculture and industry. An article co-written by a researcher at the University of Georgia and recently published in a special issue of the journal Proceedings of the National Academy of Sciences offer new support for most Reisner, findings from data and methods available for him in 1986.
Although the document focuses on sustainability of freshwater in the Southwest, co-authors Tushar Sinha, postdoctoral researcher at North Carolina State University; John Kominoski, a postdoctoral associate at the UGA Odum School of Ecology. and William Graf, Professor of geography at the University of South Carolina, said that results have important implications for the Southeast as well. "It is the Southeast has a capacity of storage of water, relatively low", said the Graf.
So that water be considered as sustainable, researchers calculated that not more than 40% of the freshwater resources may be assigned to CHMP, to ensure use of variability, navigation, entertainment and fluvial ecosystem are hosted. They were also determined how much water region must meet its municipal, agricultural and industrial needs – its footprint on virtual water. The VWF includes necessary if an area to grow enough food to sustain its own people.
Researchers have discovered that the South-West or South-East have enough water capacity to meet their own needs; These two regions import practically water from other regions of the country, in the form of food. "Southeast has virtually no VWFs positive, Interior, said Kominoski, who received his doctorate from Odum school." The greatest centres of population in the States of South-East, with the exception of Florida are internal. Piedmont cities such as Atlanta, Charlotte and Birmingham are based on small watersheds, which may be why our VWFs are negative. »
Study lead author John Sabo, associate professor at Arizona State University, said that Southeast industrial and municipal water demand is higher than supported by locally generated output.
Reisner also predicts the loss of the capacity of the reservoir. Researchers have discovered that Eastern and Western tanks lost sedimentation, storage capacity while not at the rate provided by Reisner. "The good news is that minimum lifespan of most of the dams in the South-East is more than two centuries, which is much longer than expected Reisner," said Graf.
Researchers find reservoirs lose huge quantities of water evaporation per year, which resulted in a decrease in yield reliable water. 'The United States is a higher density of tanks, but similar water losses as the West, Graf said, adding that, although there are reservoirs more to the East, they are smaller than their Western counterparts. Researchers have discovered that small reservoirs are more susceptible to evaporative losses are greatest.
Sinha added that most of these small reservoirs in the Southeast is designed to capture rain within one year, as opposed to the larger tanks West which carry water excess or deficit over several years. In addition, changes in precipitation in the Southeast quickly influence reservoir water levels. "Recent in Southeast during the summers of 2002, 2005 and 2007 drought indicate clearly the severe due to very low precipitation water shortages and water supply is dependent on the rainfall, which is likely to be more uncertain in the near future, said Sinha.".
Loss of capacity of storage and lack of enough water to meet the needs are not the issue of sustainability of freshwater in the Southeast. "The fragmentation of the River networks threaten aquatic biodiversity in South-East, which is the highest in North America in terms of native and non-native species level" said Kominoski. "Our current system does not support the needs of people, not to mention the ecosystem".
The authors also warned that the paper estimates are conservative. "The data that we have used are from 1950 to 1999," said Sinha. "The last decade, including some of the highest recorded temperature and more extreme drought, as well as figures of people, was not included." In addition, estimates do not take into account climate change. We expect to have rain in the summer, during the growing season and more severe droughts. »
Kominoski agreed and added that the 2000 census provides a continuing population growth in the sunbelt. As population grows, so demands for water, "he said." ".
Conclusion that document which Southwest is close to the limit in terms of capacity water is true for the Southeast as well. "We need a new strategy for the storage of water and conservation to United States, including the Southeast," said Kominoski. "Because we have inner metropolitan areas in small catchments, we must use less water." Less water comes to us, and our ability to store water is challenged by our climate and geographical location.
Graf said that water demand is already an issue of major disagreement among the States of South-East. "We hope that these conclusions and recommendations will inform the debate and help lead to solutions", he said.
Warning: the views expressed in this paper do not necessarily reflect those PharmaLive.com or its staff.
Source of the story:
The story above is reproduced (with drafting adaptations by staff at PharmaLive.com) materials provided by of the Georgia. The original article was written by Beth Gavrilles.
Reference of the review:
John l. Sabo, Tushar Sinha, Laura c. bowling, Gerrit h. w. Schoups, Wesley w. Wallender, Michael e. Campana, Keith a. ponds, Pam l. Fuller, William l. Graf, Jan w. Hopmans, John s. Kominoski, Carissa Taylor, Stanley w. Trimble, Robert Webb and Ellen e. Wohl. Climate and water in southwestern North America special feature: regaining sustainability of freshwater in the Cadillac desert. PNAS, 13 December 2010 DOI: 10.1073/pnas.1009734108Note: If no author is given, the source is cited for this.
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