2024 Abstracts

Watershed Dynamics and Evolution Science Focus Area Theme 3: Organizational Controls on Stream Function Within and Across Mid-Order Watersheds with Heterogeneous Land Cover


Marie Kurz1* (kurzmj@ornl.gov), Natalie Griffiths1, Dan Lu1, Matt Cohen2, Lydia Zeglin3, Adam Ward4, Jesus Gomez-Velez1, Eric Pierce1


1Oak Ridge National Laboratory, Oak Ridge, TN; 2University of Florida, Gainesville, FL; 3Kansas State University, Manhattan, KS; 4Oregon State University, Corvallis, OR



Anthropogenic activities are altering watershed hydrology and land use-land cover with cascading effects on the storage, processing, and transport of water, nutrients, carbon, sediments, metals, and contaminants from watersheds. Theme 3 of ORNL’s Watershed Dynamics and Evolution science focus area seeks to resolve the large-scale organizational controls on emergent patterns and regimes in stream function (especially stream metabolism) within and across mid-orders stream networks with heterogeneous land cover. This presentation will provide an overview of results-to-date focused on evaluating the spatiotemporal controls on network-scale synchrony/asynchrony in stream metabolism and related metrics of watershed function. Building upon earlier site-selection efforts, the team instrumented 25 mid-order watersheds within the upper and middle Tennessee River Basin (TRB) selected to be representative of extant variation within the TRB based on previous cluster analysis. High-frequency in situ sensors were installed at the outlet of each watershed in March 2023, before leaf out, to track the response in flow, temperature, specific conductivity, and dissolved oxygen (DO) over time and across systems. Researchers are using this data to test the high-level hypothesis that patterns in watershed function can be predicted by key state and forcing variables. At the first intensive watershed, East Fork Poplar Creek (EFPC), researchers have been collecting a series of measurements at 14 core sites across the stream network, including high-frequency DO, temperature, conductivity, and depth timeseries; monthly water chemistry and discharge (often coinciding with Theme 1 and/or Theme 2 sampling campaigns); and bi-monthly measurements of organic-matter decomposition using cotton strips. This EFPC data is being used to evaluate synchrony/asynchrony in metabolic processes and drivers across the stream network.