Tree-Ring Reconstruction of Flood Dynamics on the Mississippi River and Its Principal Tributaries

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This research project will develop high-resolution, multi-century reconstructions of major flooding in the Mississippi River Basin based on analyses of tree rings and to use these reconstructions to help determine the true natural variability of large magnitude flooding prior to the modern period of direct flood measurements. These reconstructions will provide a long-term context for analyses of extreme flood events that have occurred in the modern period and allow the examination of the role played in destructive flooding by regional and large-scale climate variability and other natural and human-related factors. Results of the research project will greatly increase basic understanding of long-term flood variability in the region and help develop and refine techniques useful for the study of flood history in large-river systems in North America and elsewhere. Beyond meeting specific research objectives, the project will provide education and training opportunities for undergraduate and graduate students and will provide for improved teaching of undergraduate students and others based on project findings that demonstrate the relevance of atmospheric science as well as the importance of societal resilience to natural hazards.Destructive flooding long has long plagued many communities along major rivers, including the Mississippi River and its principal tributaries. For more than a century, scientists and engineers have attempted to determine the frequency and magnitude of flooding in this river system. Scientists also have sought to understand not only the links between flooding and natural climate variability but also how potential climate change and direct human modification of the hydrology of the river may affect future flood patterns. This project will address several methodological and theoretical issues. The principal methodological questions concern whether it is possible to quantitatively reconstruct and model extreme flooding prior to the instrumental period and to determine how well the observational record represents the envelope of natural variability. Answers to both of these questions are necessary to determine broader questions concerning the link between extreme flooding and climate variability, including the questions of whether and how changes in climate and other natural and human systems may affect flood behavior and the risk to those who reside in river basin. This project will answer these questions using both tree-ring records of flooding and hydrological models to estimate the occurrence, magnitude, and discharge of major pre-instrumental floods. This approach has rarely been used in the past, and it should provide the necessary long-term context for extreme events observed in the modern period and reveal relevant links to climate forcing that will help answer questions regarding the potential impact of climate and other changes on this river system. This approach holds great promise for being applied in other river basins and for use to address other natural-hazard questions.