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，地下水和地表水的相互作用历来是由海狸的存在决定的，海狸大坝储存并将水重新引向泛滥平原。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一直在没有海狸的溪流河段安装海狸水坝模拟物(BDAS)，这是一种模仿天然海狸水坝形状的溪流恢复结构。由于其简单性和预期的好处，BDA正在美国西部得到广泛的关注和实施，尽管缺乏明确的科学数据来评估其对河流尺度水文学的影响。拟议的项目旨在解决这一知识差距，以便通过监测位于美国怀俄明州的一个包含几个生物圈保护区的研究点，确定生物圈保护区改变地下水和地表水水位、地下水-地表水交换和蒸散的程度。该项目将与怀俄明州自然保护协会(TNC-WY)密切合作，后者是研究网站的所有者和管理人。虽然拟议工作的目的是在生物多样性发展区部署的背景下提高对水文过程的了解，但观察也将为生物多样性发展区相关的几个管理目标提供信息(包括降低水流速度、重新连接河道与泛滥平原、支持河岸植被作为野生动物栖息地和牛的饲料)。调查人员将与西北大西洋渔业中心密切合作，评估这些管理目标，与当地和区域从业人员和利益攸关方分享研究结果，并利用研究地点作为BDA的示范点。该项目的主要目标是理清与流域尺度上实施BDA相关的溪流、大气(通过蒸散)和含水层(通过地下水位动态)之间的复杂反馈。为实现这一目标，将每年在研究地点收集实地和现场观测以及通过无人驾驶飞行器(无人机)获得的高分辨率图像，并结合对河流-含水层-大气反应的综合模拟来限制项目期间及以后的行为。将利用观测和数值模拟来确定生物圈保护区与蒸散、径流和地下水位之间相互作用的水文机制，以实现对生物圈保护区结构如何影响河流河段物理水文学的充分了解。本研究所采用的实证分析和基于模型的方法将直接评估研究站点对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生物多样性指标对水文过程的影响以及如何与参考范围进行比较的可转移性的见解。由于评估BDAS的机制和影响的文献几乎不存在，这项工作将为气候和人类造成变化的美国西部流域提供急需的背景。最后，这项工作将为更广泛的科学界提供一个使用无人机收集环境数据的模板，从而显著推进通过无人机收集水文和生态科学数据的领域。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.