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<br /> <br />Figure 1. Stream cross section showing flood stage and various flood features (from <br />J arret!, 1991) <br /> <br />Flood Chronology <br /> <br />To place large paleofloods in the proper historical context, paleoflood deposits are dated <br />using a variety of quaternary stratigraphy and geochronology (Baker, 1987; Levish et aI., 1994), <br />The stratigraphic position of the flood deposit provides an indication of the relative age, <br />Absolute dating of paleoflood events is usually accomplished by radiocarbon dating, <br /> <br />Radiocarbon dating is the standard tool used for absolute dating of paleoflood deposits <br />(Baker, 1987), This technique uses organic carbon found in wood, charcoal, and decayed matter <br />to date the material. Use of tandem accelerator mass spectrometry has resulted in an ability to <br />produce age estimates within 100 years for samples less than 10,000 years old (National <br />Research Council, 1999), <br /> <br />Dendrochronology is a b01:anic approach for estimating the minimum age of paleofloods, <br />Tree ring data can be used to reconstruct a flood history, Trees produce annual growth rings <br />which can be counted to determine the number of years before present that a tree scar associated <br />with a paleoflood occurred, The ability to collect botanic information varies according to the life <br />span of the prevalent tree species, Trees typically produce annual rings for tens to several <br />hundred years, and, in some trees, for thousands of years (Hupp, 1988), <br /> <br />Hydraulic Modeling <br /> <br />Once paleostage indicators have been identified, the peak discharge is computed using <br />hydraulic flow models (Baker, 1987), The step backwater method has been used most often for <br />converting paleostage to peak discharge, One-dimensional computer programs are readily <br />available for modeling steady, gradually varied flow conditions and generally produce acceptable <br /> <br />4 <br />