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.

该项目旨在确定一次具有重大地质意义的洪水事件对海岸沉积模式和速率的影响。确定运输路径将使来自宾夕法尼亚大学、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力学、海岸动力学和沼泽维护之间的联系联系起来。将研究两条截然不同的河流羽流--密西西比河本身的羽流，预计将把沉积物分散到墨西哥湾，由于其狭窄而集中的喷流，对湿地开发不会有太大贡献；阿查法拉亚河的羽流预计将扩散到整个景观，更容易沉积沉积物，滋养湿地。这项研究将利用卫星数据、物理采样和数值模拟。测量方法包括：(1)分析关于海洋表面温度、颜色和高度的卫星数据；(2)利用声学多普勒仪、表层沉积物样品和抓床样品，在密西西比河入海口收集沉积物样品；(3)测量洪水开始消退后沼泽沉积物的沉积速率。最近由两个PI开发的用于估计洪水导致的路易斯安那州沿海混合率和沉积模式的新理论将被捕获在一个模型中。该模型的结果将与密西西比河附近测量的羽流动态以及密西西比河和阿查法拉亚河沿岸陆架底部和沼泽地表面的采样沼泽沉积物进行比较，以增强对密西西比河三角洲作为沉积物扩散系统的功能的理解。人们一致认为，保护和扩大沿海沼泽对路易斯安那州沿海至关重要，但在如何做到这一点上分歧很大。需要支持对沼泽建设的科学理解，然后才能为这场辩论提供信息。该项目抓住了一个独特的机会，研究了2011年密西西比州历史性洪水中两个羽流中沉积物动力学的约束模式，旨在加强三角洲恢复的科学基础，三角洲恢复在未来几年将变得越来越重要。