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<br />OO~H'9 <br /> <br />7 <br /> <br />i <br />\. <br /> <br />Drought Historv of the Southwestern United States from Previous Studies <br />The inherent scarcity of water in the semiarid to arid regions of the south- <br /> <br />western United Stares is exacerbated by the occurrence of frequent and persistent <br /> <br />droughts. The impact of these droughts is conslanrly changing as the burgeoning <br /> <br />population places increasing demand on both supplies and disoibution systems. <br /> <br />Thus, from a user standpoint, a moderate drought in the 1960's might well be clal;- <br />sified as severe in the late 1980's. Also, prolonged dry periods reach a "crisis" <br />stage more quickly now than in the past and emphasize the need for advanced plan- <br /> <br />ning that might mitigate the effects of water shonages. <br /> <br />[n his repon to [he U, S. Congress in 1879, John Wesley Powell (Powell, <br />1879) described the arid conditions in the west with great clarity and emphasized <br />the susceptibility of the region to fre<Juent periods of drought. He funher empha- <br /> <br />( <br />, <br /> <br />sized the point that without irrigation, agriculture would be impossible. Powell <br />recognized the inherent fragility of the arid lands and recommended ways in which <br /> <br />they could best be managed. That his advice was unheeded is a matter of history. <br /> <br />The archaeological history of the southwest is a kaleidoscope of the rise and <br /> <br />fall of ancient civilizations with the availability of water. This point is illustrated by <br />the reconsrructed hisrory of Arroyo Hondo, a 14th century pueblo located 4 1/2 <br />miles south of Santa Fe, New Mexico. The town was located at an altitude of7,100 <br /> <br />feet, irrunediately west of the foothills of the Sangre de Cristo Mountains. <br /> <br /> <br />As part of a muhidisciplinary study conducted by the School of American <br /> <br /> <br />Research at Santa Fe, Rose, Dean and Robinson (1981) reconsrructed the climate of <br /> <br /> <br />the area using tree-ring chronologies developed from living trees and archaeological <br /> <br />material. Their work, along with other investigations, have made it possible to <br /> <br />\ <br /> <br />relate the development of Arroyo Hondo to climatic variations. <br />Arroyo Hondo was established around A.D. 1300 when precipitation was <br /> <br />increasing after a 50-year period of below average years. Precipitation remained <br />