Dynamics of interconnected surface-subsurface flow and reactive transport processes across the hillslope-riparian zone-river corridor continuum of cold, high-latitude watersheds
Active Dates | 9/1/2023-8/31/2026 |
---|---|
Program Area | Environmental Systems Science |
Project Description
The Arctic is warming almost four times faster than the rest of the world, in the process thawing large stores of
permafrost
soil carbon. The thawing amplifies
climate change
if the carbon is released to the atmosphere as greenhouse gases like
carbon dioxide
and
methane.
The conversion of
soil carbon
to greenhouse gases occurs in
watersheds,
and this process is largely controlled by how water flows through the soils from the hillslopes to valley-bottoms and into streams. The hydrologic processes within watersheds are shifting in response to dramatic changes in extreme weather events like heat waves, flooding and storms, and more frequent
tundra
wildfires, along with a shorter cold season and longer summer thaw season. However, scientists do not know how the concurrent thawing of permafrost soils and changes in watershed hydrology will affect greenhouse gas emissions. There is a clear need to improve models of cold-region watershed hydrology in order to predict how warming and permafrost thaw now will affect greenhouse gas release in the future. This research will use state-of-the-art mathematical models of watershed hydrology and advance them to provide the first integration of highly-dynamic water flow over the landscape, through soils, and to rivers with key physical, biological and chemical processes that control greenhouse gas generation and transport. Realistic coupling of the
hydrology,
biology, and chemistry in these models will be validated by key field observations. Our expectations are that (1) hydrological flow patterns from hillslopes through valley bottoms control the landscape export of carbon from soils to rivers and the relative production of greenhouse gases (carbon dioxide versus methane); (2) variability in extreme events, freeze-thaw cycles, and day-to-day weather will alter the magnitudes of biological and chemical reactions through the hillslope to valley-bottom and then to the river; and, (3) watershed-scale carbon exports are controlled by valley-bottom processes, but hillslope and stream processes can dominate as climate change alters weather patterns and hydrology. We will test these ideas under scenarios of shifting cold- and warm-season climate, by adding novel physics and chemistry to two coupled DOE models, the Advanced
Terrestrial
Simulator (ATS) model for thermal hydrology and PFLOTRAN for reactive chemical transport.
Award Recipient(s)
- The University of Texas at Austin (PI: Cardenas, Meinhard)