Collaborative Research: P2C2: Extreme floods on the lower Mississippi River in the context of late Holocene climatic variability

密西西比河在美国经济中扮演着重要角色，洪水泛滥在经济和社会方面都造成了巨大的损失。2011年密西西比河下游发生的历史性洪灾造成了超过30亿美元的农业损失和基础设施破坏，2016年和2018年又发生了洪灾造成的额外损失。对密西西比河及其主要支流洪水的季节性和长期预测仍然是一个重大挑战，因为气候变化、温室压力和人类对河流的修改的影响很难利用跨度不到150年的测量站的短期记录来区分。该项目将开发描述过去一千年来密西西比河流域发生洪水的时间和规模的记录，并利用这些记录来了解气候变化对洪水活动的影响。这项工作将改善对密西西比河沿岸洪水的预测，这是一种影响数百万人的危险。这些发现将有助于计划和正在进行的减缓密西西比河三角洲沿海土地流失的努力。该项目将吸引三个机构的学生参与研究，其发现将通过密西西比河博物馆和水族馆的展览向公众传播。该项目的目标是利用保存在牛弓湖中的沉积档案重建过去一千年来密西西比河下游及其主要支流的漫滩洪水的频率和规模。我们能够创造这一新的水文记录是由于古洪水水文学的最新发展，这表明了泛滥平原湖泊沉积物记录单个洪水事件及其相关规模的独特能力。一旦开发完成，我们的重建将用于表征洪水活动的十年至百年尺度的变异性，与气候模式集合中模拟的极端流量进行比较，并确定与密西西比河下游及其主要支流极端洪水可能性增加相关的区域和半球环流模式。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The Mississippi River plays a fundamental role in the economy of the United States, and flooding along its course is costly in both economic and social terms. Historic flooding of the lower Mississippi in 2011 caused over $3 billion in agricultural losses and damage to infrastructure, with additional losses to flooding occurring again in 2016 and 2018. Seasonal and longer-term predictions of flooding along the Mississippi and its major tributaries remain a major challenge because the effects of climate variability, greenhouse forcing, and human modifications of the river are difficult to disentangle using short records from gauging stations that span less than 150 years. This project will develop records describing the timing and magnitude of flooding across the Mississippi River basin over the last millennium, and use these records to understand the influence of climate variability on flood activity. This work will improve predictions of flooding along the Mississippi River, a hazard that affects millions of people. The findings will be useful for planned and ongoing efforts to slow coastal land loss in the Mississippi River delta. The project will engage students at three institutions in research, and its findings will be disseminated to the public through an exhibit at the Mississippi River Museum and Aquarium. The goal of this project is to reconstruct the frequency and magnitude of overbank floods along the lower Mississippi River and its major tributaries over the last millennium using the sedimentary archives preserved in oxbow lakes. Our ability to create this novel hydrological record is due to recent developments in paleoflood hydrology that demonstrate the unique ability of floodplain lake sediments to record individual flood events and their associated magnitude. Once developed, our reconstructions will be used to characterize decadal- to centennial-scale variability of flood activity, to compare with simulated discharge extremes in climate model ensembles, and to identify the regional and hemispheric circulation patterns associated with increased likelihoods of extreme floods on the lower Mississippi River and its major tributaries.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.