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

该项目结合了密西西比河谷上游洪泛平原地质记录中的冲积地层和地貌证据，以高分辨率尺度(如事件、年份和数十到数百年)确定过去几千年的气候变化如何影响洪水的季节性和极端洪水事件的重复间隔。一项主要目标涉及量化和模拟气候过渡时期与气候极端时期之间洪水规模和复发频率的差异，以及气候变化的相对方向(例如，温暖/潮湿到温暖/干燥与温暖。潮湿到凉爽/潮湿等)。影响洪水的幅度和频率特性。研究结果将表明洪水频率分布的形状和分散度如何随洪水分布平均值的变化而变化。气候/洪水组合的地层记录将与精选的来自欧洲和中国黄河水系的长期历史气候/洪水记录进行比较。该项目对气候和水文系统之间的联系提供了重要的“事件尺度”理解，这些联系可以为未来的气候条件而预测，这些气候条件已经为大气温室气体负荷的各种情景进行了预测。这种“事件尺度”信息通常不能从目前的全球大气环流模式中获得。

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.