Laserfiche WebLink
<br />. <br /> <br />. <br /> <br />. <br /> <br />Friday, July 12 <br /> <br />10:30 a.m.-12:00 noon <br /> <br />on plotting positions and based on fitting probability models into actual data. This paper will <br />critically examine the many alternative techniques for flood frequency analysis based on <br />systematic, historical, and paleoflood data regarding the underlying assumptions, the type of <br />data, and the results obtained. Data from the Colorado Big Thompson River and from other <br />rivers in Colorado will be used. <br /> <br />Paleoflood Evidence and Streamflow Data to Describe <br />the Spatial Occurrence of Large Magnitude Rainfall Floods <br />in Wyoming <br /> <br />Dianne L. Brien <br />Department of Geology and Geophysics <br />University of Wyoming <br /> <br />Streamflow-gauging in Wyoming display an abrupt decrease in flood magnitude at an elevation <br />of approximately 2400 m. This is consistent with studies in Colorado, wherein high elevation <br />regions do not receive the intense rainfall required to produce large-magnitude floods. However, <br />paleodischarges from the Medicine Bow Mountains, southeast Wyoming, reveal anomalously <br />high flood magnitudes for their elevation, compared to gauging data. The locations of the <br />paleoflood sites and closer examination of the gauging data suggest two ideas: 1) While the <br />flanks or foothills of mountain ranges receive large-magnitude floods, the interior of mountain <br />ranges does not. 2) Elevation limits to large-magnitude floods must be defined relative to the <br />base of the mountains and distance from the mountain front. <br /> <br />Paleohydrologic Bounds and the Frequency of Extreme Floods <br /> <br />Dan Levish and Dean Ostenna <br />U. S. Bureau of Reclamation <br /> <br />An expeditious was to evaluate the probability of large floods for the safety of critical structures <br />is to identify and assign ages to geomorphic surfaces adjacent to a river that serve as limits for <br />the paleostage of large floods over thousands of years. These paleostage limits can then be input <br />onto a step-backwater model to calculate the maximum discharge that would not significantly <br /> <br />18 <br />