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

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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.