Dynamics of interconnected surface-subsurface flow and reactive transport processes across the hillslope-riparian zone-river corridor continuum of cold, high-latitude watersheds

The Arctic is warming almost four times faster than the rest of the world, in the process thawing large stores of permafrost

permafrost

Any ground that remains completely frozen—32°F (0°C) or colder—for at least two years straight. These permanently frozen grounds are commonly found in regions with high mountains and near the North and South Poles.

Source: USGS Source

soil carbon.  The thawing amplifies climate change

climate change

A change in the average conditions — such as temperature and rainfall — in a region over a long period of time.

Source: NASA Climate Kids Source

if the carbon is released to the atmosphere as greenhouse gases like carbon dioxide

carbon dioxide (CO2)

An important heat-trapping gas, also known as a greenhouse gas, that comes from the extraction and burning of fossil fuels (such as coal, oil, and natural gas), from wildfires, and natural processes like volcanic eruptions.

Source: NASA Source

and methane.

methane

A hydrocarbon that is a primary component of natural gas. Methane is also a greenhouse gas (GHG), so its presence in the atmosphere affects the earth’s temperature and climate system

Source: EPA Source

  The conversion of soil carbon

soil carbon

The measurable amount carbon dioxide stored in soil. It is the primary indicator of soil health, and it impacts the chemical, physical, and biological characteristics of the soil.

Source: Science Direct Source

to greenhouse gases occurs in watersheds,

watershed

An area of land that channels rainfall and snowmelt to creeks, streams, and rivers, and eventually flows to the lowest point in a basin.

Source: USGS Source

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

tundra

A type of ecosystem dominated by lichens, mosses, grasses, and woody plants. Generally located at high latitudes (arctic tundra) and high altitudes (alpine tundra).

Source: NASA earth observatory Source

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,

hydrology

The science that deals with water, its properties, circulation, or distribution on Earth's surface, and in the atmosphere through evapotranspiration.

Source: NASA earth observatory Source

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

terrestrial

The geographical and biological features that are associated with the Earth's solid, rocky surface, residing on or resembling the land or terrain found on our planet.

Source: NASA Source

Simulator (ATS) model for thermal hydrology and PFLOTRAN for reactive chemical transport.