9713206 House Extreme flooding in western Nevada in early January 1997 has provided a scientifically important opportunity to collect ephemeral field data that can serve to characterize the physical signature of large flood events in both fluvial and lacustrine environments in this region. Historical weather and streamflow records from affected river basins in western Nevada indicate that previous, comparably extreme events have resulted from analogous hydroclimatological and hydrometeorological phenomena. Thus, it is likely that the largest paleoflood events preserved in fluvial and lacustrine settings in the region resulted from generally similar circumstances. The proposed data collection effort will focus on high-water mark distribution and flood deposit characteristics in selected river reaches to evaluate both the fidelity of persistent flood features to peak flood stages and the sedimentological characteristics of extreme flood deposits in a variety of depositional settings. In selected lacustrine environments, water, ostracode, and mollusk samples are being collected at regular intervals to document time-dependent changes in geochemical characteristics of both biotic and abiotic lacustrine phenomena. The ultimate goal of the project is to develop robust geomorphic, sedimentologic, and geochemical analogs that can be used to discern similarly extreme events in the stratigraphic record in fluvial and lacustrine environments typical of this region. It is important to collect the field data as soon as possible because much of the flood evidence is either ephemeral, time-dependent, or subject to modification through ongoing mitigation efforts. Impending spring runoff provides an additional unique opportunity to compare and contrast the effects from distinctly different types of hydrologic events.
