þ7#$Z|G^^***8.°°°¸  ÌÌ<xfJ€  w*¡Û*w¶Áww|wwwwww 1994-10 Embargoed until: March 30, 1994 Contact: Joan Vandiver Frisch Manager, NCAR Media Relations Boulder, CO (80307-3000 Telephone: 303-497-8607 Email: jfrisch@ncar.ucar.edu Diversion of Rivers by Humans Could Cause Regional Climate Change in Delta Area Ecosystems, Predicts NCAR Social Scientist SAN FRANCISCOÑWhen humankind messes with Mother Nature, the consequences can be much more damaging than previously envisioned, according to a paper, "Modeling the Effects of Anthropogenic Changes on River Delta Development," which will be presented at the annual meeting of the Association of American Geographers on March 30 in San Francisco. David Smith, a geographer with the Environmental and Societal Impacts Group at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, will present a scenario of impacts that regional and global climate changes may have on fragile ecosystems around the mouths of rivers when humans decide to divert excessive amounts of water from their natural courses. A particular focus of Smith's work is on river deltas, which are universally recognized for their fertile soils and abundance of water. As a consequence, they are also characterized by intense agricultural production and high population densities. "Any changes in regional climate would affect the regional hydrologic character of rivers and deltas and thus may entail particularly high economic and social costs," reports Smith. "Clearly, this has been the case in the Aral Sea basin in South Central Asia." Smith uses as an example, a case study of the glacier-fed Amu Darya and Syr Darya rivers, which flow northward into the Aral Sea, supplying most of the freshwater needs of Central Asia as well as of the sea. He traces the ecological damage and regional climate change caused by a shrinking of the sea's surface area that has resulted from human over exploitation of the rivers. Water diversion projects for increased irrigation from the two main river systems in the region have distorted the hydrologic character of the Aral Sea basin and have led to landscape changes hat have already significantly affected regional patterns of runoff and ecosystem quality. These changes in turn, reports Smith, affected regional climatic characteristics hotter summers and colder winters. Regional climate became more continental, as the sea's influence over its surrounding areas declined. The following is the sequence of events that led to significant ecosystem changes in the two deltas. The desire of former communist leaders to increase agricultural production in central Asia led to an acceleration in the amount of land within the basin put under irrigation beginning in the early 1960s (from 1 million hectares in 1990, to 4.5 million in 1960, to 7.5 million in 1992.) With the expansion of irrigated land came a need to increase the amount of water diverted from rivers and streams as well as amounts of fertilizers, herbicides and pesticides. At the same time, return flow was diverted to closed, interior drainage basins and not allowed to return to the rivers from which the water had been drawn. This led to a rapid decline in water availability in and a drying out of the fertile deltas of the Syr Darya and Amu Darya. Smith's detailed assessment of actual regional climate change and variability and their impacts on the sustainability of inland river deltas includes an examination of the past attempts at development of the deltas of the Aral Sea basin, present anthropogenic factors in recent delta changes, and the relationships between future ecosystem and climatic changes (derived from modeling and paleoclimatic studies) that are likely to occur. Smith has developed a framework for the study of inland river deltas in other parts of the world to serve as an "ecological blueprint" for water resource managers before they implement irreversible, destructive water diversion projects. NCAR is sponsored by the National Science Foundation and managed by the University Corporation for Atmospheric Research, a consortium of 61 universities with Ph.D. programs in the atmospheric or related sciences. ter summers and colder winters. FRANCISCOÑWhen humankind interferesby generating His paper will appear in a forthcoming issue of Post-Soviet Geographyse}ifelse}bËFXYZ[{| ®ºàõ^lŒ©ÍÒÓâã)H†Š     !"#$)*úôúúúúúúúúîèúúúúúúúúúúúúúúúúú @ @( À( (& 67UuªÊËGH¡ ‰ Ù€XYZ|ÓÔã  "$*ûûûûûûûûûûûûûûûûûöûððêäÞØÒÌÇÌÇÇÞÇêÇÇÇÇÇ#(à#(à#(àà #(à#(à#(à#( #( ' ÿÿÿÿÿÿÿÿÿÿÿ Geneve 11 ptÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ ôöÞ with the title: "Climate Change, Climate Variability, and Ecosystem Decline in the Deltas of the Aral Sea Basin." -The End- Once lying entirely within the borders of the USSR, the Aral Sea basin is occupied by the newly independent republics of Turkmenistan, Uzbekistan, Tadzhikistan, Kyrgyzstan, two southern provinces of Kazakhstan: Qyzlorda and Shymkent, and part of northern Afghanistan and northeastern Iran. - former Soviet Union, Smith I@ÿÿÿÿËIÿÿß@ÿÿ¤PÿÿHù ® þ`8I#(#( #(#(#(* *  !"Ð×áèíôöøþ Ó9Û:~HHÚ(ÿáÿâùF(üHHÚ(d'@=à/ÐÐpÐ8ÐR@H -:LaserWriter ChicagoNew YorkGenevaMonaco San Francisco Zapf DingbatsBookmanN Helvetica NarrowPalatino Zapf ChanceryTimes HelveticaCourierSymbol! 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