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起着至关重要的作用，其沿岸的洪水在经济和社会方面都是昂贵的。2011年密西西比河下游的历史性洪水造成了超过30亿美元的农业损失和基础设施破坏，2016年和2018年再次发生的洪水造成了额外的损失。对密西西比河及其主要支流的季节性和长期洪水预测仍然是一个重大挑战，因为气候变化、温室效应和人类对河流的改造的影响，很难用跨度不到150年的监测站的短记录来解开。该项目将开发描述过去一千年中密西西比河流域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，这是一个影响数百万人的危险。这些发现将有助于减缓密西西比河三角洲沿海土地流失的计划和正在进行的努力。该项目将让三所机构的学生参与研究，其研究结果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轭湖的沉积档案，重建过去一千年来密西西比河下游及其主要支流河岸洪水的频率和规模。我们创造这种新的水文记录的能力是由于古洪水水文学的最新发展，它证明了洪泛区湖泊沉积物记录单个洪水事件及其相关规模的独特能力。一旦得到发展，我们的重建将用于表征洪水活动的年代际到百年尺度的变化，与气候模型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。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.