CAREER: Active Learning Across Interfaces: Controls on Flow Intermittency and Water Age in Temporary Streams

超过三分之一的美国人口依靠临时溪流——并不总是有水流入的渠道——来获得水的供应。美国最高法院和环境保护署最近都注意到了解这些河流的重要性，以确保全国各地都有可捕鱼、可游泳和可饮用的水。令人惊讶的是，预测何时何地河流会干涸，以及哪些河流最有可能从全年流动转变为干旱期间偶尔干涸，仍然是一项挑战。该项目将通过绘制河流流向地图，并将这些地图与预期控制（包括降雨、融雪、植物用水和地下特征）联系起来，解决这一差距。我们会收集水样，以测试这些不同的流量控制是否会影响水质。这些样本还将表明溪水以雨或雪的形式落下的时间，这可能会影响溪流干涸的频率。此外，该项目还将培养从小学到研究生的尖端临时河流科学的多元化学生。将开发新的课程，培训大学生掌握环境领域的方法，并让河流向导与激流爱好者分享临时的溪流科学。最后，该项目将与流域管理者合作，对他们管理的临时河流进行更廉价、更科学的研究。临时流？有间歇或短暂流动的河道？为美国约三分之一的人口供水，并在许多水源系统中维持河流生态健康。需要研究具有流动地表水的渠道的动力学-主动排水网络-以及该网络对气候和土地利用变化的敏感性。这项工作考察了一系列地点的主动排水网络动态的潜在控制，包括多个NSF关键区域观测站。该项目将绘制主动排水网络的地图，以及将降水、蒸散发和推断的透过率模式与主动排水网络联系起来的模型，包括间歇性对水质的潜在影响。该研究的核心假设是，透过率是水流持久性的主要控制因素，主动排水网络的空间变化反映了水力导电性、几何形状和水龄。该项目将通过培训不同的本科生和研究生群体进行临时溪流科学的教学和研究，并通过密集的环境实地方法课程，指导本科生研究，以及与美国爱达荷州麦考尔户外科学学校合作，与K-12学生和河流向导进行外展，使他们参与实地研究。最后，该项目将通过与当地流域管理者进行有针对性的联合研究和修复工作的反复合作，改善区域河流管理成果。

Over 1/3 of the United States' population relies on temporary streams--channels that do not always have water flowing in them--for their water supply. The U.S. Supreme Court and the Environmental Protection Agency have both recently noted the importance of understanding these streams to ensure fishable, swimmable, and drinkable waters throughout the country. Surprisingly, it remains challenging to predict where and when streams will run dry, and which streams will be most likely to shift from flowing year-round to occasionally running dry during droughts. This project will address that gap by mapping where streams are flowing, and linking these maps to expected controls including rainfall, snowmelt, plant water use, and below-ground characteristics. We will collect water samples to test whether these different controls on flow affect water quality. These samples will also indicate how long ago the stream water fell as rain or snow, which may affect how often a stream dries up. In addition, the project will train a diverse group of students from elementary school through graduate school in cutting-edge temporary stream science. New courses will be developed to train college students in environmental field methods and to engage river guides in sharing temporary stream science with whitewater enthusiasts. Finally, the project will work with watershed managers to develop cheaper and better scientific insight into the temporary streams they manage.Temporary streams ?channels with either intermittent or ephemeral flows ? supply water for ~1/3 of the US population and sustain stream ecological health in many headwater systems. Research is needed on the dynamics of channels with flowing surface waters--the active drainage network--and the sensitivity of this network to changes in climate and land use. This work examines potential controls on active drainage network dynamics across a suite of sites, including multiple NSF Critical Zone Observatories. This project will lead to mapped active drainage networks as well as models linking precipitation, evapotranspiration and inferred transmissivity patterns to the active drainage network, including potential effects of intermittency on water quality. The central hypothesis is that transmissivity is the primary control on flow permanence, and that spatial variations in the active drainage network reflect hydraulic conductivity, geometry, and water age. This project will integrate teaching and research by training a diverse undergraduate and graduate student population in temporary stream science, and by engaging them in field research through an intensive environmental field methods course, mentored undergraduate research, and outreach with K-12 students and river guides in collaboration with the U. Idaho McCall Outdoor Science School. Finally, the project will improve regional stream management outcomes through iterative collaboration on targeted joint research and restoration efforts with local watershed managers.