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<br />I <br /> <br />INTRODUCTION <br /> <br />On May 18, 1996 a forest fire burned much of the vegetation in a ~the Buffalo <br /> <br />Creek watershed, approximately 35 miles southwest of Denver, Colorado. Two months later, on <br />~. <br /> <br />July 12 1996, a thunderstorm event led to intense flooding, erosion, and property damage in the <br /> <br />town of Buffalo Creek (photo I). An estimated 2 to 3 inches of rainfall fell in less than an hour <br /> <br />over approximately 10 square miles (citizen estimates, Denver Post 1996). Rainfall <br /> <br />measurements by Buffalo Creek residents suggest that more than 2.5 inches of rain fell in 45 <br /> <br />minutes (Denver Post 1996). The 100-year flood for Buffalo Creek at the town of Buffalo Creek <br /> <br />(the confluence with Sand Draw) is 630 cubic feet per second (cfs) with a 500-yr discharge or <br /> <br />840 cfs (Federal Emergency Management Agency (FEMA) 1989); the estimated peak discharge <br />d <br /> <br />1lW" B, <br />/ <br />~ <br /> <br />in Buffalo Creek during the July event was about 17,000 cubic feet per second (written <br /> <br />communication, Jarrett 1997). ;./' <br /> <br />Development of hydrophobic (water repellent) soils, decreased interception, reduced <br /> <br />storage and decreased permeability may have contributed to a larger proportion of overland flow <br /> <br />generation on the fire-affected hillslopes of Buffalo Creek. A look at basin hydrology in the <br /> <br />Buffalo Creek watershed could offer insight as to how fire-affected slopes react to storms of <br /> <br />different intensity, duration, and magnitude. In this study, a rainfall frequency analysis utilizing <br /> <br />the method ofL-moments with data from Eastern Colorado will approximate the probability of <br /> <br />such a rainfall event occurring in the future. Due to the absence of an official rain gage in the <br /> <br />basin, a distribution of hyetographs are generated to represent the possible rainfall scenarios to <br /> <br />represent the July storm. Sand Draw, a small subwatershed of the Buffalo Creek basin (photos 2 <br />