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

这项研究项目将在树木年轮分析的基础上，对密西西比河流域的主要洪水进行高分辨率、多世纪的重建，并使用这些重建来帮助确定现代直接洪水测量时期之前大规模洪水的真实自然变异性。这些重建将为分析现代时期发生的极端洪灾事件提供长期背景，并使人们能够审查区域和大规模气候变化以及其他自然和人为因素在破坏性洪灾中所起的作用。该研究项目的成果将大大增加对该地区长期洪水变异性的基本了解，并有助于开发和改进有助于研究北美和其他地区大河流系统洪水历史的技术。除了实现具体的研究目标外，该项目还将为本科生和研究生提供教育和培训机会，并将根据项目结果改善本科生和其他人的教学，这些结果证明了大气科学的相关性以及社会对自然灾害的复原力的重要性。破坏性洪水长期以来一直困扰着包括密西西比河及其主要支流在内的主要河流沿线的许多社区。一个多世纪以来，科学家和工程师一直试图确定这一河流系统中洪水的频率和规模。科学家们不仅试图了解洪水和自然气候变异性之间的联系，而且还试图了解潜在的气候变化和人类对河流水文的直接修改可能如何影响未来的洪水模式。该项目将解决几个方法和理论问题。主要的方法论问题涉及是否有可能在仪器期之前对极端洪灾进行定量重建和建模，并确定观测记录在多大程度上代表了自然变率的包络。对这两个问题的回答对于确定有关极端洪水和气候变异性之间联系的更广泛问题是必要的，包括气候和其他自然和人类系统的变化是否以及如何影响洪水行为以及对居住在河流流域的人的风险的问题。这个项目将使用洪水的树轮记录和水文模型来回答这些问题，以估计主要仪器前洪水的发生、规模和流量。这种方法过去很少使用，它应该为现代观察到的极端事件提供必要的长期背景，并揭示与气候强迫的相关联系，这将有助于回答有关气候和其他变化对这一河流系统的潜在影响的问题。这一方法很有希望应用于其他河流流域，并用于解决其他自然灾害问题。

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.