Responses of Flood Magnitudes and Frequencies to Climatic Changes Since c. 2000 years B.P.

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This project incorporates the use of alluvial stratigraphic and morphologic evidence in the geologic record of Upper Mississippi Valley floodplains to determine at a high resolution scale (e.ge., event, years, and decades to centuries) how climatic changes of the last few thousand years have influenced the seasonality of floods and the recurrence intervals of extreme flood events. A major objective involves quantifying and modelling how flood magnitudes and recurrence frequencies differed between times of climatic transition versus time of climatic extremes, and how the relative direction of climatic change (e.g. warm/moist to warm/dry versus warm.moist to cool/moist etc.) influences flood magnitude and frequency characteristics. Results of the research will indicate how the shape and dispersion of a flood frequency distribution change with changes in the mean of a flood distribution. The stratigraphic record of climate/flood associations will be compared with selected long historical climate/flood records from Europe and from the Yellow River system of China. The project provides important "event scale" understandings of linkages between climatic and hydrologic systems that might be anticipated for future climatic conditions that have been projected for various scenarios of atmospheric greenhouse gas loadings. This type of "event scale" information generally is not available from present global atmospheric circulation models.