Collaborative Research: The Role of Flocculent Organic Sediment Transport as a Feedback Mechanism that Controls Landscape Dynamics and Restoration Success in the Everglades

拟议的研究验证了一个假设，即沉积物运输动力学在控制地形模式方面发挥作用，而地形模式对佛罗里达大沼泽地的山脊和沼泽景观的生态至关重要。也就是说，在历史流动条件下，假设沉积物从开放水域的沼泽到植被覆盖的山脊的再分配调节了山脊的宽度，但随着沼泽地的排水和分区化，再分配的幅度减小，允许山脊扩展为开放水域的沼泽和地形异质性的丧失。项目假设将通过现场和实验室实验以及控制絮状沉积物运输动力学和植被环境中流量的质量和动量平衡方程的数值模拟相结合进行测试。对絮体输运力学的实验分析将描述在沉积床中导致粒径偏离的临界剪应力和湍流强度，由不同剪切参数的流动引起的平衡粒径分布和浓度，聚集体沉降速度，以及由于植被和微地形而发生在山脊/沼泽横截面上的湍流和流动剖面的变化。为此目的，将在实验室和现场水槽中使用天然絮体进行流量监测和一系列运输实验和示踪剂测试。基金还将资助森林山高中环境科学磁体项目的学生执行补充科学博览会项目，该项目将重点关注使用快速评估光学技术开发跨山脊/沼泽样带的有机物质混合模型（可用作沉积物运输模型的验证措施），并阐明环境水质对絮状有机沉积物运输特性的影响。知识价值。提出的研究建立在先前的研究基础上，通过建立一个模型来预测沉积的大小和空间分布，作为流速和水位的函数，表明存在从开放水域渠道到植被环境的沉积物再分布。在沼泽地，沉积物主要以有机絮凝体的形式存在，其机制尚不清楚。同样，尽管絮凝作用在世界各地河流、湿地和河口的悬沙动力学中起着主导作用，但关于流经植被环境对絮凝物沉积和运移影响的研究以及絮凝动力学对景观形态和演化的预测模型尚不存在。本研究开发了一套实验室和现场实验，旨在解决模型开发所需的关于絮体运输机制的关键问题，并建立了这些机制如何影响景观演化的原始模型。因此，拟议的研究将为改善沉积物运输和景观动力学的预测开创先例，这将对河口科学、河流地貌学、湿地科学和污染物运输产生影响。更广泛的影响-本项目的结果将广泛传播给(1)该领域的研究人员，通过在ASLO会议上组织一次关于絮凝剂沉积物输送对景观动力学影响的特别会议，并随后出版一期特刊；(2)通过pi定期参加景观小组会议和大沼泽地生态系统恢复会议，参与实施“沼泽地综合恢复计划”的决策者；(3)通过发表一篇关于沼泽地景观动态的科普文章，向公众开放。此外，模型结果将对政策和社会产生影响，导致对流速和水期的改进建议，这些建议应该被实施，以恢复山脊和沼泽景观。由于购买激光衍射粒度分析仪而增强的基础设施将有利于K-12、本科和研究生水平的课堂演示、实验室和实地研究。研究工作还将加强美国地质勘探局、科罗拉多大学和K-12教育之间的合作，并将协同补充美国地质勘探局现有的关于生物地球化学反馈机制和山脊和沼泽景观内营养物质运输的项目。最后，这项研究通过与佛罗里达州西棕榈滩森林山高中的环境科学磁体项目建立坚定的合作伙伴关系，并通过为当前的博士生提供研究支持，增强了对未来几代科学家的知识转移。

The proposed research tests the hypothesis that sediment transport dynamics play a role incontrolling the topographic patterning that is crucial to the ecology of the ridge and slough landscape inthe Florida Everglades. Namely, under historical flow conditions, it is hypothesized that sedimentredistribution from open-water slough to vegetated ridge regulated ridge width but that, with drainage andcompartmentalization of the Everglades, the magnitude of redistribution has decreased, permittingexpansion of ridges into open-water sloughs and loss of topographic heterogeneity.Project hypotheses will be tested through a combination of field and laboratory experimentationand numerical modeling of the mass and momentum balance equations governing flocculent sedimenttransport dynamics and flow in vegetated environments. Experimental analysis of floc transportmechanics will describe the critical shear stresses and turbulence intensities that entrain size classes offloc in a deposited bed, equilibrium aggregate size distributions and concentrations resulting from flowwith different shear parameters, aggregate settling velocities, and changes in turbulence and flow profilesthat occur across a ridge/slough cross-section as a result of vegetation and microtopography. To this end,flow monitoring and a series of transport experiments and tracer tests using natural floc will be performedin laboratory and field flumes. Funds will also sponsor the execution of complementary science fairprojects by Forest Hill High School environmental science magnet program students, which will focus onusing a rapid-assessment optical technique for developing an organic matter mixing model across aridge/slough transect (which can be used as a validation measure for the sediment transport model) and onelucidating the effects of ambient water quality on flocculent organic sediment transport properties.Intellectual merit. The proposed research builds upon previous research showing the existence ofsediment redistribution from open-water channels to vegetated environments by producing a model topredict the magnitude and spatial distribution of sedimentation as a function of flow velocity and waterlevel. In the Everglades, sediment occurs primarily in the form of organic floccules, the mechanics ofwhich are not well understood. Similarly, although flocculation plays a dominant role in the suspendedsediment dynamics of rivers, wetlands, and estuaries throughout the world, studies on the impacts of flowthrough vegetated environments on sedimentation and transport of floccules and predictive models of flocdynamics on landscape morphology and evolution are nonexistent. This research develops a set oflaboratory and field experiments designed to address the critical questions about floc transport mechanicsrequired for model development and an original model of how these mechanics influence landscapeevolution. Thus, the proposed research will set a precedent for improved predictions of sedimenttransport and landscape dynamics that will have implications for estuarine science, fluvialgeomorphology, wetlands science, and contaminant transport.Broader impacts - Results of this project will be broadly disseminated to (1) researchers in the field,through organization of a special session at an ASLO meeting on implications of flocculant sedimenttransport for landscape dynamics and subsequent publication of a special journal issue, to (2) policymakers involved in implementation of the Comprehensive Everglades Restoration Plan through regularparticipation of the PIs in Landscape Subteam meetings and the Greater Everglades EcosystemRestoration conference, and to (3) the general public, through publication of a popular science article onEverglades landscape dynamics. Further, model results will impact policy and society by leading toimproved recommendations of flow velocities and hydroperiods that should be implemented to restore theridge and slough landscape. Enhanced infrastructure resulting from the purchase of a laser diffractionparticle size analyzer will benefit classroom demonstrations, laboratory, and field research at the K-12,undergraduate, and graduate levels. Research efforts will also enhance collaborative efforts between theUSGS, University of Colorado, and K-12 education and will synergistically complement an existingUSGS project on biogeochemical feedback mechanisms and nutrient transport within the ridge and sloughlandscape. Finally, this research enhances the knowledge transfer to future generations of scientiststhrough a committed partnership with the environmental science magnet program at Forest Hill HighSchool in West Palm Beach, Florida and by providing research support to a current Ph.D student.