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

这项研究验证了沉积物输运动力学在控制地形格局中发挥作用的假设，地形格局对佛罗里达大沼泽地的山脊和斯劳景观的生态至关重要。也就是说，在历史水流条件下，假设沉积物从开放水域斯劳分布到植被山脊调节山脊宽度，但随着大沼泽地的排水和分隔，再分布的幅度减小，把山脊扩张成开阔的-将通过现场和实验室实验以及对水的数值模拟相结合的方式来测试项目假设。质量和动量平衡方程控制絮状沉积物运输动力学和流动在植被环境。絮凝体运输力学的实验分析将描述临界剪切应力和湍流强度，夹带在沉积床，平衡聚集体的大小分布和浓度，从不同的剪切参数，聚集体沉降速度，以及湍流和水流剖面的变化，发生在一个山脊/斯劳横截面的结果，植被和微地形的流量。为此，将在实验室和现场水槽中进行流量监测和一系列使用天然絮凝物的输送实验和示踪剂试验。基金还将赞助森林山高中环境科学磁铁项目学生执行补充科学公平项目，重点是利用快速评估光学技术建立一个跨越干旱/斯劳样带的有机物混合模型（可用作泥沙输运模式的验证措施）阐明了环境水质对絮凝有机泥沙输运特性的影响。拟议的研究建立在以前的研究表明存在的沉积物再分配从开放的水道到植被环境，通过产生一个模型来预测作为流速和水位的函数的沉积的大小和空间分布。在大沼泽地，沉积物主要以有机絮凝物的形式出现，其机理尚不清楚。同样，虽然絮凝在世界各地的河流、湿地和河口的悬浮泥沙动力学中起着主导作用，但关于流过植被环境对絮凝物沉积和运输的影响以及絮凝物动力学对景观形态和演变的预测模型的研究却不存在。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絮凝物运输力学的关键问题，以及这些力学如何影响絮凝物演变的原始模型。因此，拟议的研究将为改进对沉积物输运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、湿地科学和污染物输运产生影响。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迁移对景观动态的影响的特别会议，并随后出版一期特别期刊，（2）通过定期参加景观小组会议和大沼泽地生态系统恢复会议，参与实施大沼泽地综合恢复计划的政策制定者，以及（3）通过发表关于大沼泽地景观动态的科普文章，向公众宣传。此外，模型结果将影响政策和社会，导致改进的建议，流速和水文周期，应实施恢复山脊和斯劳景观。购买激光衍射粒度分析仪所带来的增强型基础设施将有利于K-12、本科和研究生阶段的课堂演示、实验室和实地研究。研究工作还将加强美国地质调查局、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调查局现有的关于海脊和泥沼景观中生物地球化学反馈机制和营养物质输送的项目。最后，本研究通过与佛罗里达西棕榈滩森林山高中的环境科学磁铁项目建立伙伴关系，并为当前的博士生提供研究支持，增强了向后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.