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.

该项目的非技术性描述，解释了该项目的重要性和重要性海平面上升和地面沉降的综合影响造成的沿海土地损失是 21 世纪的一个主要问题。上游大坝后面沉积物的滞留以及堤坝对主要河流的限制，导致输送到沿海地区的沉积物减少，从而加剧了地面沉降问题。在美国墨西哥湾沿岸，通过对密西西比河进行工程改道，将沉积物输送到三角洲平原的大部分地区，可以减少土地损失。模拟模型是规划此类改道和评估不同管理方案对海岸沉积和侵蚀速率影响的重要工具。然而，对造成沿海沉积物预算的不同过程的了解存在差距，可能会导致模型对这些速率的预测不准确。这些未知过程之一是沿海植被的茎和叶直接捕获颗粒，这在三角洲沼泽中可能会大大增加总体沉积率。这项研究将量化植被捕获对沿海沉积预算的重要性，从而改进对沿海生长或淹没的预测。该项目的技术描述该项目解决了记录细沉积物在沿海土地建设过程中的作用的三个突出主题：（i ）它通过植被的直接捕获，建立了水动力特性、生物膜和植被特性以及沉积之间的定量关系。 (ii) 它检验了植被阵列中生物膜的存在会显着增加沉降速率的假设。 (iii) 改进了三角洲陆地动力学模型中植被捕获颗粒的表征，并利用该模型评估颗粒捕获在大规模三角洲演化中的整体意义。将结合实验室和现场实验以及数值建模来阐明这些主题。生物地貌学研究与教学 (BRAT) 水槽中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积的影响。这些结果将在蜡湖三角洲（路易斯安那州海岸生长活跃的部分）完整植被群落周围建造的原位水槽内进行现场测试。在现场和实验室水槽中开发的功能关系将被纳入三角洲沉积动力学的代尔夫特 3D 模型中。使用该模型进行的敏感性分析将评估精细沉积物-植被相互作用对于大规模三角洲生长的重要性。该项目的教育部分包括开发使用 BRAT 水槽的体验式课程模块、在国家地球动力学中心开发关于精细沉积物与植被相互作用的夏季短期课程，以及为旧金山探索馆开发关于该作用的展览。土地建设过程中沿海沼泽的影响。三角洲建模工作将与沿海资源管理者合作开发，并广泛传播以用于路易斯安那州沿海沼泽恢复规划。