SGER: Hurricane Katrina Storm Surge Deposition on Deltaic Wetlands

SGER：卡特里娜飓风风暴潮沉积在三角洲湿地

• 批准号: 0612501
• 负责人: Robert Turner
• 金额: --
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2007-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0612501&HistoricalAwards=false
• 关键词: SGER; Hurricane; Katrina; Storm; Surge

(1) Technical description A small exploratory grant is proposed to collect sediments deposited on wetlands by Hurricanes Katrina and Rita. The amount of sediments that hurricanes leave in wetlands has been documented at a few discrete locations along this coast, but there are no coast wide measurements of this deposition, and no post-deposition studies of their stability. The paleo-chronology of sediment cores from this coast demonstrates the coincidence of peaks in inorganic concentration when hurricanes occur. A conservative estimate is that the net annual accumulation of sediments from a hurricane storm surge is 30X higher than once arrived from overbank flooding of the formerly levee-free Mississippi River, and 200 times greater than from either of the two river diversions meant to restore wetlands (built @$100 million each). This is a timely opportunity to quantify the amounts delivered by strong storms in a systematic way and to contribute to the science infrastructure necessary to efficiently and effectively restore this highly degraded coast. The general purpose of the field sampling is to: 1) estimate the sediment volume brought to wetland environment by these hurricanes, 2) collect sufficient material to characterize (with other funding instruments) its content and subsequent movement into soils or re-mobilization; and, 3) discern relationships, if any, between sediment deposition and both plant composition and wetland geomorphology. Samples will be collected using a helicopter for up to 4 days, for approximately 6 hours daily (weather permitting). Data collection will consist of site photographs, measurements of sediment depth, various sediment collections, and archiving material of representative plants and easily accessible invertebrates such as snails and crabs. The sample collection volume will be sufficient to conduct analyses of particle size, CNS stable isotopes in soils and plants, and routine soil and plant analyses (e.g., salinity, % organic, C/N ratios, trace metals, exchangeable cations, etc. (2) non-technical explanation of the broader significanceA small exploratory grant is proposed to collect sediments deposited on wetlands by Hurricanes Katrina and Rita. The tidal surges moving inland through the St. Bernard estuary and into the New Orleans area left significant amounts of sediments in the urbanized portion of the watershed, and unknown amounts elsewhere. These sediments may be of significant factor in wetland stability because of either their volume or the nutrients attached to them. The amount of sediments that hurricanes leave in wetlands has been documented at a few discrete locations along this coast, but there are no coast wide measurements of this deposition amount, or post-deposition studies of their stability. A rapid response sample collection is necessary before visual identification of the layer is much more difficult, if not impossible. The main purposes of this proposed sample collection are to quantify the amount of sediments introduced to these wetlands by these hurricanes, to understand how the deposition rate varies across the landscape, and to estimate their importance to wetland stability. The archived samples must be analyzed using other funding instruments.An analysis of dated sediment cores from this coast demonstrates the coincidence of peaks in inorganic concentration when hurricanes occur. A preliminary analysis of these data, and using conservative parameter values, suggests that the net annual accumulation of sediments from a hurricane storm surge is much higher than once arrived from overbank flooding of the formerly levee-free Mississippi River or from either of the two river diversions (built @$100 million each) meant to restore this severely degraded coast. The available restoration approaches bringing sediments and nutrients to wetlands are neither trivial nor homogenous endeavors; they are a heterogeneous mixture of size, cost : benefit ratios, predictability and consequences. There are, therefore, significant management implications of this proposed work. These results will have an immediate application to the evaluation of restoration strategies, which are currently focused on the large scale diversions of sediments in the Mississippi River to theoretically 'sediment deprived' and 'nutrient stressed' wetlands. Additional benefits of this sample collection and subsequent analyses include being able to trace the movement of sediment-bound nutrients into plants, to offer data to calibrate sediment transport models and carbon sequestration in wetlands, and to establish permanent plots to follow soil evolution.

(1)建议提供一笔小额探索赠款，收集卡特里娜和丽塔飓风在湿地上沉积的沉积物。 飓风在湿地中留下的沉积物数量在沿着的几个离散地点都有记录，但没有对这种沉积进行海岸范围的测量，也没有对其稳定性进行沉积后研究。 该海岸沉积物岩心的古年代学表明，飓风发生时无机物浓度的峰值重合。 据保守估计，飓风风暴潮造成的沉积物年净积累量比以前无堤坝的密西西比河漫滩洪水造成的沉积物年净积累量高30倍，比旨在恢复湿地的两条河流改道（每条改道耗资1亿美元）的沉积物年净积累量高200倍。 这是一个及时的机会，可以系统地量化强风暴带来的数量，并为有效恢复这一高度退化的海岸所需的科学基础设施做出贡献。 实地取样的一般目的是：1）估计这些飓风给湿地环境带来的沉积物量，2）收集足够的材料（与其他供资工具一起）说明其内容和随后进入土壤或重新动员的情况;以及3）辨别沉积物沉积与植物组成和湿地地貌之间的关系（如果有的话）。 将使用直升机采集样本，最多持续4天，每天约6小时（天气允许）。数据收集将包括现场照片、沉积物深度测量、各种沉积物收集以及代表性植物和容易获得的无脊椎动物（如蜗牛和螃蟹）的档案材料。 样品采集量将足以进行土壤和植物中的颗粒大小、CNS稳定同位素分析以及常规土壤和植物分析（例如，盐度、%有机物、C/N比、微量金属、可交换阳离子等。 (2)一个小的探索性赠款，建议收集沉积在湿地上的卡特里娜飓风和丽塔的非技术性解释。 潮汐潮通过圣伯纳德河口向内陆移动，进入新奥尔良地区，在流域的城市化部分留下了大量沉积物，其他地方的沉积物数量不详。 这些沉积物可能是湿地稳定性的重要因素，因为它们的体积或附着在它们上面的营养物质。飓风在湿地中留下的沉积物数量在沿着的几个离散地点都有记录，但没有对这种沉积量进行海岸范围的测量，也没有对其稳定性进行沉积后研究。 在对层进行视觉识别之前，快速响应样品收集是必要的，如果不是不可能的话，也要困难得多。 这一拟议的样本收集的主要目的是量化这些飓风引入这些湿地的沉积物的量，了解沉积速率如何在景观中变化，并估计其对湿地稳定性的重要性。 存档的样本必须使用其他资助工具进行分析。对该海岸的过时沉积物岩心的分析表明，飓风发生时无机物浓度的峰值重合。 对这些数据的初步分析，并使用保守的参数值，表明从飓风风暴潮沉积物的净年度积累是远远高于以前的无堤密西西比河的漫滩洪水或从两个河流改道（每1亿美元）旨在恢复这一严重退化的海岸。 现有的恢复方法，使沉积物和营养物质的湿地既不是微不足道的，也不是同质的努力，他们是一个异构的混合物的大小，成本：效益比，可预测性和后果。 因此，这项拟议的工作涉及重大的管理问题。 这些结果将有一个直接的应用恢复策略，这是目前集中在大规模改道沉积物在密西西比河理论上的“沉积物剥夺”和“营养强调”湿地的评价。 这种样本收集和随后分析的其他好处包括能够追踪沉积物结合的营养物质进入植物的运动，提供数据以校准沉积物迁移模型和湿地中的碳固存，并建立永久性地块以跟踪土壤演变。