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

该项目旨在确定地质上重大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点联系起来。两种对比鲜明的河流羽流将被研究。——密西西比河本身，由于其狭窄、集中的射流，预计会将沉积物分散到海湾，对湿地的发展没有太大的贡献；以及阿查法拉亚河，预计会在整个景观中扩散，更容易沉积沉积物来滋养湿地。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)分析卫星海面温度、颜色和高度数据；(2)利用声学多普勒船测法在密西西比河出口处收集沉积物样本、地表沉积物样本和河床取样；(3)在洪水开始消退时测量沼泽地沉积物的增加速率。其中两个pi最近开发了一种新理论，用于估计路易斯安那州沿海地区由洪水引起的混合率和沉积模式，该理论将被纳入一个模型。该模型的结果将与密西西比河外测量的羽流动力学，以及从密西西比河和阿查法拉亚河沿岸的陆架底部和沼泽表面取样的沼泽沉积物进行比较，以加强对密西西比河三角洲作为沉积物分散系统如何发挥作用的理解。人们一致认为，保护和扩大沿海沼泽对路易斯安那州沿海地区至关重要，但在如何做到这一点上却没有达成一致意见。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，研究了2011年历史性的密西西比河洪水中两股沉积物动力学的对比模式，旨在加强三角洲恢复的科学基础，这在未来几年将变得越来越重要。

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.