RAPID: Connecting the historic 2011 Mississippi River flood to marsh sedimentation on the Delta

RAPID：将 2011 年密西西比河历史性洪水与三角洲沼泽沉积联系起来

• 批准号: 1140269
• 负责人: Douglas Jerolmack
• 金额: $ 5万
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-15 至 2012-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1140269&HistoricalAwards=false
• 关键词: RAPID; Connecting; historic; 2011; Mississippi

The project aims to determine the impact of a geologically significant flood event on coastal sedimentation patterns and rates. Determining transport pathways will enable researchers from University of Pennsylvania, University of Mississippi, and the U.S. Geological Survey to connect the dots between river dynamics, coastal dynamics, and marsh maintenance. Two contrasting river plumes will be studied?-that of the Mississippi River itself, which is expected to disperse sediment into the Gulf and not contribute greatly to wetland development because of its narrow, focused jet, and that of the Atchafalaya River, which is expected to spread diffusely across the landscape and be more prone to deposit sediment to nourish wetlands. The research will make use of satellite data, physical sampling, and numerical modeling. Measurement approaches are (1) analysis of satellite data on sea surface temperature, color, and height; (2) collection of sediment samples at the outlet of the Mississippi River using a boat survey with acoustic dopplar, surface sediment samples, and bed grab samples, and (3) measurement of marshland sediment accretion rates once the floodwaters begin to subside. New theory recently developed by two of the PIs for estimating mixing rates and sedimentation patterns in coastal Louisiana resulting from the flood will be captured in a model. The results of the model will be compared with measured plume dynamics off the Mississippi River, and sampled marsh sediments from the shelf bottom and marsh surfaces along the Mississippi and Atchafalaya Rivers, to enhance understanding of how the Mississippi Delta functions as a sediment dispersal system.There is consensus that protecting and expanding coastal marshes is vital for coastal Louisiana but much less agreement on how to do it. Scientific understanding of marsh building needs to be bolstered before it can inform this debate. This project seizes a unique opportunity to examine constrasting modes of sediment dynamics in two plumes from the historic 2011 Mississippi floods, and aims to enhance the scientific basis for delta restoration that will become increasingly important in the years to come.

该项目旨在确定地质上重大的洪水事件对沿海沉积模式和速率的影响。 确定运输路径将使宾夕法尼亚大学、密西西比大学和美国地质调查局的研究人员能够将河流动态、海岸动态和沼泽维护之间的联系联系起来。 两个对比鲜明的河流羽流将被研究？一个是密西西比河本身，预计它会将沉积物分散到海湾中，由于其狭窄而集中的射流，对湿地的发展不会有很大的贡献;另一个是阿查法拉亚河，预计它会在整个景观中扩散，更容易产生存款沉积物来滋养湿地。这项研究将利用卫星数据、物理采样和数值模拟。 测量方法有：（1）分析关于海洋表面温度、颜色和高度的卫星数据;（2）使用声学多普勒、表面沉积物样品和河床抓斗样品进行船测，在密西西比河出口处收集沉积物样品;（3）一旦洪水开始消退，测量沼泽地沉积物的堆积速率。 新的理论最近开发的两个PI估计混合率和沉积模式在路易斯安那州沿海造成的洪水将被捕获在一个模型中。 该模型的结果将与密西西比河外测得的羽流动力学以及密西西比河和阿查法拉亚河沿着陆架底部和沼泽表面的沼泽沉积物取样进行比较，以提高对密西西比三角洲作为沉积物扩散系统如何发挥作用的认识。人们一致认为，保护和扩大沿海沼泽对路易斯安那州沿海地区至关重要，但对如何做到这一点的共识要少得多。在为这场辩论提供信息之前，需要加强对沼泽建筑的科学理解。该项目抓住了一个独特的机会，研究从历史性的2011年密西西比洪水的两个羽流沉积物动力学的约束模式，并旨在加强三角洲恢复的科学基础，这将在未来几年变得越来越重要。