Collaborative research: Linking scales of geomorphology and solute transport in river corridors

作者：Aaron Packman（西北大学），Douglas Jerolmack（宾夕法尼亚大学），Jud Harvey（美国地质调查局）概述：河流中的溶质运移是一个复杂的问题，受水文和地貌动力学的影响。预测水文动力学、地貌动力学和溶质运移之间的相互作用，对于提高对河流水系长期平均生物地球化学加工速率的评价具有重要意义。河流-地下水文相互作用受地表形态的调节，强烈影响河流和孔隙水中的溶质运输，从而控制着非常广泛的生物地球化学过程。在这里，我们建议获得一个独特的新数据集，包括河流形态动力学和溶质输运在一个频繁的高流量和沉积物输运事件的沙床河流的观测。我们还建议发展新的理论，将以前在地貌学和地表水-地下水相互作用中观察到的尺度关系纳入河流长期平均溶质运输的模型中。该模型将通过结合观察到的河流流量变化和河道形态的统计数据应用于研究地点，并将通过直接观察溶质渗透到地下和净下游溶质在一定时间尺度上的平均迁移来进行测试。知识价值：这项工作的知识价值在于促进了对河流水文学、河流形态动力学、地表水-地下水相互作用和河流溶质运输之间联系的基本理解。这是一个非常复杂的问题，因为它不仅涉及湍流边界相互作用，而且涉及高度非均质近流环境中的沉积物输运和孔隙流体流动。在这里，我们将综合最近在水文学和地貌学中单独发展的许多观察和假设，以确定河流中流动动力学和形态动力学之间的联系如何在不同的空间和时间尺度上控制溶质运输。虽然现在普遍认识到，为了以综合方式评价环境系统的行为，需要进行这种综合，但在实践中很少实现这种综合。通过开发利用地貌和水文尺度关系共性的新理论，我们能够明确评估河流廊道中各种时空尺度上控制溶质运移动力学的综合过程。更广泛的影响：拟议的努力将对环境科学以及水资源和水生生态系统的相关管理作出非常广泛的贡献。此外，通过各种协同活动，我们还将在人力资源开发和整个科学界实现许多更广泛的影响。该项目的结果将为评估河流系统中各种重要溶质的迁移提供重要的、必要的能力。迫切需要能够用于预测形态变化（例如，土地利用变化）和可变水文强迫（自然流量变率和备选气候变化情景）下长期平均运输行为之间联系的工具。因此，项目结果不仅有助于详细了解河流动态，而且在支持分析河流系统中碳、营养物质、污染物和一系列其他重要物质的迁移和加工方面具有非常广泛的影响。从本质上讲，项目努力是朝着以科学为基础的淡水资源可持续管理迈出的关键一步。我们将通过支持更广泛的科学界在这些问题上的工作，进一步加强这些一般性贡献。我们将把我们将获得的独特的现场数据集存档，并将其公开提供给其他理论家和建模者，以促进更广泛的开发和测试河流走廊的流量和运输模型。我们还将通过在主要技术会议上召集多个直接的跨学科会议，以及将项目成果直接转化为目前由美国国家科学基金会赞助的更广泛的水文综合活动，促进科学论述，特别是科学成果的综合，以解决政策和管理问题。最后，我们将通过这项工作培训许多年轻的研究人员，通过参与协同和协作的国际活动，并通过利用项目成果进一步努力鼓励大学预科学生，特别是来自代表性不足的少数民族的学生进入科学事业，从而实现对人力资源开发的广泛贡献

PIs: Aaron Packman (Northwestern University), Douglas Jerolmack (University of Pennsylvania), Jud Harvey (U.S. Geological Survey)Overview: Solute transport in rivers is a complex problem influenced by both hydrologic and geomorphic dynamics. It is important to be able to predict the interactions of hydrologic dynamics, geomorphic dynamics, and solute transport in order to improve assessment of long-term average biogeochemical processing rates in river systems. Stream-subsurface hydrologic interactions are modulated by surface morphology and strongly affect solute transport in both streams and pore waters, thereby controlling a very wide range of biogeochemical processes. Here we propose to obtain a unique new data set encompassing observations of both fluvial morphodynamics and solute transport in a sand-bed river subject to frequent high-flow and sediment-transport events. We also propose to develop new theory to allow scaling relationships previously observed in both geomorphology and surface-groundwater interactions to be incorporated into a model for long-term average solute transport in rivers. The model will be applied to the study site by incorporating observed statistics of stream flow variations and channel morphology, and will be tested using direct observations of both solute penetration into the subsurface and net downstream solute transport averaged over a range of time scales.Intellectual Merit: The intellectual merit of this work lies in advancing fundamental understanding of the linkage between stream hydrology, fluvial morphodynamics, surface-groundwater interactions, and solute transport in rivers. This is an exceedingly complex problem as it involves not only turbulent flow-boundary interactions, but also sediment transport and pore fluid flow in the highly heterogeneous near-stream environment. Here we will synthesize numerous recent observations and hypotheses developed separately in hydrology and geomorphology in order to ascertain how the linkage between flow dynamics and morphodynamics in rivers controls solute transport over various spatial and temporal scales. While it is now generally recognized that such synthesis needs to be done in order to assess the behavior of environmental systems in an integrated fashion, such integration has rarely been achieved in practice. By developing new theory that takes advantage of commonality in geomorphic and hydrologic scaling relationships, we enable explicit evaluation of the integrated process that control solute transport dynamics over a variety of spatial and temporal scales in river corridors.Broader Impacts: The proposed effort will contribute very broadly to environmental science and the associated management of water resources and aquatic ecosystems. Further, through a variety of synergistic activities we will also realize numerous broader impacts in human resource development and in the scientific community at large. The project results will provide significant, necessary capability to evaluate the migration of a wide range of important solutes in river systems. There is a critical need for tools that can be used to predict the linkage of morphological variations (e.g., land-use changes) and long-term average transport behavior under variable hydrologic forcing (natural flow variability and alternative climate change scenarios). Therefore the project results can be expected to not only contribute detailed understanding of river dynamics, but also to have very broad impacts in supporting analysis of the migration and processing of carbon, nutrients, contaminants, and a range of other important substances in river systems. Essentially, the project efforts provide a critical step towards scientifically based sustainable management of freshwater resources. We will further enhance these general contributions by supporting the broader scientific community working on these problems. We will archive the unique field data set that we will acquire, and make it publicly available to other theoreticians and modelers to facilitate broader development and testing of models for flow and transport in river corridors. We will also facilitate scientific discourse, and particularly synthesis of scientific results to address policy and management questions, by convening multiple, directed interdisciplinary sessions at major technical conferences, and by translating project results directly into the broader Hydrologic Synthesis activity currently sponsored by NSF. Finally, we will realize broad contributions to human resource development by training numerous young investigators through this work, by engaging in synergistic and collaborative international activity, and by using project results to further our ongoing efforts to encourage pre-college students, and particularly students from under-represented minorities, to enter careers in science