CAREER: The role of organic particulates in controlling the growth of river deltas: a field, experimental, and numerical modeling study

职业：有机颗粒在控制河流三角洲增长中的作用：现场、实验和数值模拟研究

• 批准号: 1455362
• 负责人: Laurel Larsen
• 金额: $ 69.75万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-01 至 2020-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1455362&HistoricalAwards=false
• 关键词: CAREER; role; organic; particulates; controlling

A non-technical description of the project, which explains the project's significance and importanceCoastal land loss through the combined effects of sea-level rise and land subsidence is a major concern of the 21st century. The retention of sediment upstream behind dams and confinement of major rivers by levees have resulted in diminished sediment delivery to coastal regions, exacerbating problems of land subsidence. Along the US Gulf Coast this loss of land may be lessened through engineered diversions of the Mississippi River that would deliver sediment to a larger portion of the delta plain. Simulation modeling is an essential tool for planning such diversions and evaluating impacts of different management scenarios on rates of coastal sedimentation and erosion. However, a gap in knowledge of the different processes contributing to coastal sediment budgets could lead to inaccurate model predictions of these rates. One of these unknown processes is the direct capture of particles by the stems and leaves of coastal vegetation, which in deltaic marshes might add substantially to overall sedimentation rates. This research will quantify the importance of vegetation capture for coastal sedimentation budgets, leading to improved prediction of coastal growth or submersion.A technical description of the projectThis project addresses three outstanding topics in documenting the role of fine sediment in coastal land building processes: (i) It develops a quantitative relationship between hydrodynamic properties, biofilm and vegetation properties, and sedimentation through direct capture by vegetation. (ii) It tests the hypothesis that the presence of biofilm within vegetation arrays substantially increases sedimentation rates. (iii) It improves the representation of particle capture by vegetation in models of delta land dynamics and uses the model to evaluate the overall significance of particle capture in large-scale delta evolution. A combination of laboratory and field experimentation and numerical modeling will be used to elucidate these topics. Laboratory experiments in the Biogeomorphology Research and Teaching (BRAT) flume will test emerging theory about the functional relationship between flow conditions, particle characteristics, and vegetation canopy structure. Biofilms cultivated within the flume will enable testing of the effects of different surficial properties on sedimentation. These results will be tested in the field, within in situ flumes constructed around intact vegetation communities in the Wax Lake Delta, an actively growing portion of the Louisiana coast. Functional relationships developed in the field and laboratory flumes will be incorporated into a Delft 3D model of delta sedimentation dynamics. Sensitivity analyses conducted with the model will evaluate the importance of fine sediment-vegetation interactions for large-scale delta growth. Educational components of the project include development of experiential course modules that use the BRAT flume, development of a summer short course on fine sediment-vegetation interactions at the National Center for Earth Dynamics, and development of an exhibit for the San Francisco Exploratorium on the role of coastal marshes in land building processes. Delta modeling efforts will be developed in collaboration with coastal resource managers and disseminated broadly for Louisiana coastal marsh restoration planning.

对该项目的非技术描述，通过海平面上升和土地沉降的综合影响来解释该项目的重要性和重要的土地损失，这是21世纪的主要关注点。在大坝后面的上游的沉积物保留和堤防对主要河流的限制导致沉积物递减到沿海地区，加剧了土地沉降的问题。在美国墨西哥湾沿岸，通过密西西比河的工程改道可以减少土地的损失，这将为三角洲平原的大部分地区提供沉积物。仿真建模是规划这种转移和评估不同管理方案对沿海沉积和侵蚀速率的影响的重要工具。但是，了解导致沿海沉积物预算的不同过程的知识差距可能导致对这些速率的模型预测不准确。这些未知的过程之一是沿海植被的茎和叶直接捕获颗粒，在三角洲沼泽中可能会大大增加整体沉积率。这项研究将量化植被捕获对沿海沉积预算的重要性，从而改善对沿海生长或沉浸的预测。该项目的技术描述涉及记录精细沉积物在沿海土地建设过程中的作用的三个杰出主题：（i）它通过蔬菜和植物的捕获与蔬菜的捕获与蔬菜之间的定量关系来建立，并通过捕获蔬菜，并通过蔬菜和种如用物进行了实现。 （ii）它检验了以下假设：植被阵列中生物膜的存在大大增加了沉积率。 （iii）它在三角洲土地动力学模型中改善了植被捕获的粒子捕获的表示，并使用模型来评估大规模三角洲进化中粒子捕获的总体意义。实验室和现场实验和数值建模的组合将用于阐明这些主题。生物地球化学研究与教学（BRAT）的实验室实验将测试有关流动条件，颗粒特征和植被冠层结构之间功能关系的新兴理论。在水槽内培养的生物膜将能够测试不同表面特性对沉降的影响。这些结果将在田间进行测试，围绕在路易斯安那州海岸积极生长的蜡湖湖湖中的完整植被群落建造。在现场发展的功能关系，实验室水肿将纳入DELTA沉积动力学的DELFT 3D模型中。使用该模型进行的灵敏度分析将评估精细沉积物蔬菜相互作用对大规模增长的重要性。该项目的教育组成部分包括开发使用小型水槽的体验式课程模块，在国家地球动力学中心开发有关精美沉积物蔬菜相互作用的夏季短期课程，以及开发旧金山探险家展览在沿海地区在土地建筑过程中的作用。三角洲建模工作将与沿海资源经理合作开发，并为路易斯安那州沿海沼泽恢复计划进行广泛传播。