Laserfiche WebLink
<br />. <br /> <br />. <br /> <br />. <br /> <br />Friday, July 12 <br /> <br />1 :15 p.m.-2:45 p.m. <br /> <br />Bayesian Flood Frequency Analysis with <br />Paleohydrologic Bounds for Late Halocene Paleofloods, <br />Santa Ynez River, California <br /> <br />Dan O'Connell, Dan Levish, and Dean Ostenna <br />U.S. Bureau of Reclamation <br /> <br />Paleohydrologic bounds demonstrate that peak discharges exceeding 1980 mA3/s had not been <br />exceeded on the Santa Ynez River in 700 years and 2900 years, respectively. These <br />paleohydrologic bounds are combined with gage and historic data in a Bayesian approach to <br />estimate flood-frequency probabilities. The Bayesian analysis uses likelihood functions that <br />incorporate both parameter and data (discharge and geologic age) uncertainties. High-speed <br />workstations make it possible to calculate parameter and peak discharge frequency probabilities <br />using systematic parameter-space searches and direct numerical integration. Bayesian peak <br />discharge frequency calculations demonstrate the value of the paleohydrologic bounds for an <br />hydrologic risk analysis of Bradbury Dam. If only gage and/or historic data are available, an <br />inescapable conclusion is that a flow exceeding spillway capacity (4520m"3/s) is likely to occur <br />within a 10,000 year period. However, adding the paleohydrologic bounds to the Bayesian <br />capacity is less than 2 in 10 million. The bayesian analysis demonstrated the substantial <br />statistical gain provided by paleohydrologic bounds by putting large historic discharges in their <br />proper Holocene contexts and by substantially reducing the range of possible discharges <br />associated with long return periods. <br /> <br />A Paradox at the Rocky Mountain Arsenal, Colorado: <br />Benefits of Applied Research <br /> <br />Robert D. Jarrett, Joseph P. Capesius <br />U.S. Geological Survey <br />and <br />Mark A. Gonzales <br />University of Denver <br /> <br />The Rocky Mountain Arsenal (RMA), which is located north of Denver, Colorado, was a <br />manufacturing site for chemical weapons during World War II and pesticides for several decades <br /> <br />20 <br />