Collaborative Research: Where does the water go: Improving understanding of stream-aquifer-atmosphere interactions around Beaver Dam Analogues

在干旱的美国西部，由于海狸的存在，地下水和地表水的相互作用在历史上已经形成，海狸大坝储存并将水重新引导到洪泛区。随着海狸数量的减少，当地市政当局、州政府机构和私人土地所有者开始在没有海狸的河流流域安装类似海狸坝（BDAs）的河流修复结构，模仿天然海狸坝的形式。尽管缺乏明确的科学数据来评估bda对河段尺度水文的影响，但由于其简单性和预期的效益，bda在美国西部得到了广泛的关注和实施。拟议的项目旨在解决这方面的知识差距，以便通过监测位于美国怀俄明州的一个含有几个bda的研究地点来确定bda改变地下水和地表水水平、地下水-地表水交换和蒸散作用的程度。该项目将与怀俄明州自然保护协会（TNC-WY）密切合作，该协会拥有并管理该研究地点。虽然拟议的工作旨在提高对BDA部署背景下水文过程的理解，但观测结果也将为与BDA相关的几个管理目标提供信息（包括降低流速，重新连接河道与洪泛平原，支持河岸植被为野生动物栖息地和牲畜饲料提供支持）。调查人员将与TNC-WY密切合作，评估这些管理目标，与当地和区域从业人员和利益相关者分享调查结果，并利用研究地点作为bda的示范地点。该项目的主要目标是解开河流、大气（通过蒸散）和含水层（通过潜流交换和地下水位动力学）之间复杂的反馈，这些反馈与流域尺度上BDA的实施有关。为了实现这一目标，每年将在研究地点收集现场和原位观测以及通过无人驾驶飞行器（UAV）获得的高分辨率图像，并与河流-含水层-大气响应的综合建模结合使用，以约束项目期间及以后的行为。将利用观测和数值模拟来确定控制BDA与蒸散、河流流量和地下水位之间相互作用的水文机制，以充分了解BDA结构如何塑造河流流域的物理水文。本研究采用实证分析和基于模型的方法，直接评估研究地点对BDA安装的反应。此外，经验分析和基于模型的分析都将产生关于bda对水文过程的影响以及如何将其与参考河段进行比较的可转移见解。由于评估bda机制和影响的文献几乎不存在，这项工作将为美国西部流域提供急需的背景，那里由于气候和人类的变化正在发生碰撞。最后，通过为更广泛的科学界提供使用无人机进行环境数据收集的模板，这项工作将显著推进通过无人机进行水文和生态科学数据收集领域。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In the arid western US, groundwater-surface water interactions have been historically shaped by the presence of beavers, with beaver dams storing and redirecting water into the floodplain. As populations of beavers have declined, local municipalities, state agencies, and private landowners have been installing beaver dam analogues (BDAs), a stream restoration structure that mimics the form of natural beaver dams, in beaver-less stream reaches. Due to their simplicity and expected benefits, BDAs are gaining extensive attention and implementation across the western US, in spite of the absence of clear scientific data to assess their impacts on reach scale hydrology. The proposed project aims to address this gap in knowledge in order to determine the extent to which BDAs alter groundwater and surface water levels, groundwater- surface water exchange, and evapotranspiration by monitoring a research site containing several BDAs located in Wyoming, USA. The project will be performed in close collaboration with The Nature Conservancy of Wyoming (TNC-WY), who owns and manages the research site. While the proposed work aims to improve understanding of hydrological processes in the context of BDA deployment, observations will also inform several management goals associated with BDAs (including reducing stream velocity, reconnecting the stream channel to the floodplain, and supporting riparian vegetation for wildlife habitat and forage for cattle). Investigators will work in close collaboration with TNC-WY to evaluate these management goals, to share findings with local and regional practitioners and stakeholders, and to leverage the research site as a demonstration site for BDAs.The primary objective of this project is to disentangle the complex feedbacks between the stream, atmosphere (via evapotranspiration), and aquifer (via hyporheic exchange and water table dynamics) associated with BDA implementation at the watershed scale. To address this objective, field and in situ observations as well as high resolution imagery via unoccupied aerial vehicle (UAV) will be collected annually at research sites and used in combination with integrated modeling of stream-aquifer-atmosphere responses to constrain behavior during the length of the project and beyond. Observations and numerical modeling will be leveraged to determine the hydrological mechanisms governing interactions between BDAs and evapotranspiration, streamflow, and groundwater levels to achieve a full understanding of how BDA structures shape the physical hydrology of stream reaches. Empirical analyses and model-based approaches employed in this study will directly assess the responses of the research site to BDA installation. In addition, both empirical and model-based analysis will yield transferrable insight regarding the impacts of BDAs on hydrological processes and how this compares with reference reaches. As the body of literature assessing the mechanisms and impacts of BDAs is virtually nonexistent, this work will provide much-needed context for western US watersheds where changes due to climate and humans are colliding. Finally, this work will significantly advance the field of data collection via UAV for hydrological and ecological sciences by providing the broader scientific community with a template to use UAVs for environmental data collection.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.