\n Speaker: Dr. Jim Dungan Smith of USGS at the University of Colorado. Sponsored by the Miles Lowell and Margaret Watt Edwards Endowm ent\, College of Engineering. Seminar begins at 4:00\, followed by\n socia l and refreshments at 5:00. http://cce.oregonstate.edu/\n
\n\nDTSTART:20080118T000000Z DTEND:20080118T023000Z X-OSU-CONTACT-DEPT:Civil & Construction Engineering X-OSU-CONTACT-PHONE:541-737-8057 X-OSU-LOCATION:Memorial Union X-OSU-ROOM:Powell Leadership Room X-OSU-SUBTITLE: - The 4th Edwards Lecture LAST-MODIFIED:20080910T161141Z CREATED:20070925T210156Z DTSTAMP:20070925T210156Z CONTACT:Prof. Harry Yeh END:VEVENT BEGIN:VEVENT UID:20080118T003000Z-16544@calendar.oregonstate.edu CLASS:PUBLIC SUMMARY:Learn more about the University Honors College DESCRIPTION:Please join us to learn more about the amazing opportunities th e UHC has to offer. Current students and staff will be available to answer questions\, tours of our space will be given\, and light\nrefreshments will be provided. DTSTART:20080118T003000Z DTEND:20080118T013000Z X-OSU-ADDRESS:170 SW Waldo Place X-OSU-CITY:Corvallis X-OSU-CONTACT-DEPT:University Honors College X-OSU-CONTACT-EMAIL:leeann.baker@oregonstate.edu X-OSU-CONTACT-PHONE:541-737-6400 X-OSU-COST:Free X-OSU-LOCATION:Strand Agriculture Hall X-OSU-ROOM:233 X-OSU-STATE:OR LAST-MODIFIED:20071207T000641Z CREATED:20071207T000641Z DTSTAMP:20071207T000641Z CONTACT:LeeAnn Baker END:VEVENT END:VCALENDAR\n During the past century rivers were treated primarily as conve yances for water and were modeled by empirical equations developed for irri gation canals. This thinking still serves as the unstated\n basis for mo st field investigations and modeling studies of natural channels. Unfortuna tely\, the overwhelming characteristic of most rivers is the irregularity o f their beds\, banks\, paths\, and\n floodplain surfaces. When concerned only with water discharge\, this irregularity was treated using a single e mpirically adjusted roughness parameter\, such as Manning’s coefficient. The use of a\n quantitatively unpredictable empirical roughness coeffici ent\, however\, makes accurate predictive modeling of discharge impossible. It also makes high-flow sediment transport and geomorphic\n adjustment calculations too inaccurate to be of much scientific or engineering value. This talk will describe how predictive models for water discharge can be co nstructed using basic fluid\n mechanical techniques and simple field mea surements of channel shape and the physical and biological roughness elemen ts on the beds\, banks and floodplains of rivers. It also will describe how \n these measurements make possible the accurate modeling of the compone nt of boundary shear stress responsible for sediment movement.\n
\n < p>\n The presentation will then show comparisons of empirically generate d and predictive-model-derived rating curves with data from many USGS gagin g stations in the Western United States and describe\n the multitude of scientific and engineering advantages of model-derived rating curves over e mpirical ones. These advantages include substantially increased accuracies and significantly lower\n costs per gaging station. Our predictive flow model makes it possible to calculate (1) velocity fields\, (2) turbulence f ields\, (3) bed-load transport fields\, (4) bed\, bank\, and floodplain ero sion\n fields\, and (5) bed and floodplain morphological rearrangement\, if any\, throughout the measurement reach at a full range of river stages. It also makes it possible to calculate (1) size-by-size\n suspended sed iment concentration and flux fields from a single time series of size-by-si ze sediment concentrations procured at a near-bed point\, (2) size-by-size sediment discharges from that\n single near-bed time series\, and (3) sp ecies-by-species sorbed contaminant discharge from chemical analyses of the sorbed material on the various sizes of sediment in near-bed sediment samp les.\n Owing to the lower cost of model-based water-discharge gaging sta tions\, they can be used in large numbers to gage river networks (1) for fl ash-flood prediction and\, (2) in conjunction with\n multi-parameter rad ar rainfall measurements\, for comprehensive scientific regional hydrologic and hydrometeorological investigations\, such as ultimately will be motiva ted by CUHASI and supported\n by NSF.\n \n\n In flood-conse quence-prediction and river-restoration problems it is essential to be able to calculate accurately (1) cut-bank erosion rates resulting from high flo ws\, and (2) deposition on\n floodplains resulting from the fluid-mechan ical drag on floodplain plants with specific allometries (particularly thos e with woody stems and branches)\, verses unbounded downward erosion due to \n above critical boundary shear stresses produced by overbank flows. Fu lly predictive procedures for calculating overbank flows on vegetated flood plains will be described and reconstructions of two\n multi-century-recu rrence-interval floods using these fully predictive algorithms will be pres ented. In one case\, dense willows penetrating the overbank flow caused app roximately 0.3 meters of\n highly contaminated mine tailings to be depos ited over many tens of kilometers during a five-day flood in Montana\, and in the other case\, downstream of beaverpond- supported dense willow carrs\ , a\n cottonwood-tree and small-shrub-covered floodplain was completely washed away. In the first case\, the river channel was hardly affected by t he flood and in the second case the river channel\n became almost straig ht\, its width increased by a factor of ten\, and antidunes planed the new channel bottom (now composed of sand from the old floodplain) into an excee dingly flat surface. Ten\n years ago accurate reconstructions of such fl oods were impossible owing to the lack of fully predictive river channel an d floodplain flow models.\n
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