Watershed Dynamics and Evolution Science Focus Area Theme 2: Stream Corridor Processes

Authors

Scott C. Brooks¹* ([email protected]), Erin R. Hotchkiss², Eric M. Pierce¹

Institutions

¹Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN; ²Department of Biological Sciences, Virginia Tech, Blacksburg, VA

URLs

• https://www.esd.ornl.gov/programs/rsfa/

Abstract

Within Oak Ridge National Laboratory’s Watershed Dynamics and Evolution (WaDE) SFA, Theme 2 will characterize stream corridor processes at the reach scale using a combination of field experiments, laboratory mesocosm studies, and modeling. This work is motivated by the knowledge that mid-order streams are reactive conveyors that receive, process, and transport carbon, nutrients, and other solutes from upstream and the surrounding uplands. Furthermore, these mid-order streams are a vital link between low-order headwaters and larger rivers. Nevertheless, they are noticeably underrepresented in the research literature, so quantitative understanding of their roles in watershed function is lacking. These experiments and data analyses are designed to address specific questions and hypotheses related to (1) quantifying the contributions of water column gross primary production and ecosystem respiration to net ecosystem production across gradients in land cover, (2) elucidating the effects of organic matter burial in the stream benthos on aerobic versus anaerobic metabolism, and (3) assessing the resistance and resilience of reach-scale gross primary production and ecosystem respiration to disruption by transient high-flow events.

To address these research focuses, scientists will establish three long-term observation stations in the Theme 2 research watershed, the location of which will be selected to coincide with dominant land cover categories in the region. Each station will be equipped with multiparameter sondes, including dissolved O₂ and CO₂ sensors, as well as pressure transducers in stilling wells to measure and record high–temporal resolution water quality and discharge data. Observations and experiments will be tiered in spatial and temporal scale from individual bottle experiments (hours) to laboratory flume experiments (weeks to months) to long-term observation records in the field (months to years). Experimental design will be informed by data from WaDE SFA Theme 1 and provide results used in Theme 3 (please see accompanying posters). The Theme 2 team will collaborate with microbiologists and microbial ecologists to inform data interpretation and analysis. Additionally, data will be used to inform development of a virtual watershed, which will be applied to data interpretation and the design of new experiments.