The Role of Snowmelt on the Hydrology and Carbon Dioxide Dynamics in Headwater Streams Across the East River Watershed, CO, USA
Presenter: Riley Scott Cole
Faculty Sponsor: Matthew Winnick
School: UMass Amherst
Research Area: Geology and Earth Sciences
Session: Poster Session 6, 4:15 PM - 5:00 PM, 163, C14
ABSTRACT
Snowmelt-dominated headwater streams play an important role in the global carbon cycle. Snowmelt provides large subsurface flushing events, mobilizing CO2 that eventually degasses in streams. However, the amount of CO2 entering headwater streams is difficult to predict and may depend on watershed carbon source limitations versus water transport controls. To understand the role of precipitation and water transport in watershed-scale stream CO2 emissions, we investigated hydrometeorological and geochemical datasets in the East River Basin (ERB) in the Rocky Mountains of Colorado over interannual scales. We used SNOTEL and PRISM precipitation to differentiate precipitation on snow versus bare ground. Additionally, the Lawrence Berkeley National Laboratory (LBNL) open-source dataset was used to compile stream discharge and geochemical data across 11 sites in the ERB during water years 2014 - 2021. Cumulative water year precipitation during snow‑cover periods produced a stronger relationship with discharge at 10 of the 11 sites. We modeled in-stream CO2 concentrations (pCO2) from available geochemical data and air-water gas exchange velocity for CO2 (kCO2) to calculate CO2 fluxes (FCO2) from these sites. Overall, the relationship between pCO2, kCO2, and FCO2 was compared with the precipitation and discharge data to investigate relationships across spatiotemporal scales. Our results demonstrate how robust geochemical datasets can be used to help relate snowmelt to stream CO2 degassing, which must be better characterized as climate and hydrology in watersheds change.