T103 Applications and Developments of Coupled Hydrologic Models

Monday, 28 October 2013
8:00 AM - 12:00 PM
Room 301

SIMULATION OF COUPLED SURFACE-SUBSURFACE HYDROLOGIC AND TERRESTRIAL ECOSYSTEM PROCESSES USING PFLOTRAN AND CLM

Paper number: T103-5
Program: Technical Sessions
Time: 9:15 AM – 9:30 AM

Authors

Abstract

Current Earth system models greatly simplify or completely omit some key physical processes, such as lateral flow of water and heat, surface-subsurface interactions, realistic groundwater-vadose zone interactions, and freeze-thaw dynamics. Capturing the effects of such processes is critically important for improving our understanding of climate change impacts on hydrology and associated climate feedbacks. Towards this end, we have added non-isothermal coupled surface-water groundwater interactions and a multi-phase ice model to PFLOTRAN--an open-source, massively parallel hydrologic flow and reactive transport model--and have developed a framework for coupling it with the Community Land Model (CLM), the state-of-the-art LSM component of the Community Earth System Model (CESM).

In the coupled CLM-PFLOTRAN model, PFLOTRAN replaces the CLM treatment of surface and subsurface thermal hydrology. CLM provides sources and sinks of water (evapotranspiration, snowmelt, and precipitation) and heat flux; while PFLOTRAN evolves the subsurface soil moisture and thermal states (including freeze-thaw dynamics). This allows a unified treatment of the unsaturated and saturated zones (which are decoupled in standalone CLM) and enables lateral redistribution of surface and subsurface water and heat. In addition to hydrologic coupling, we are developing a biogeochemistry linkage to enable interaction between CLM plant functional types and PFLOTRAN subsurface biogeochemistry.

We will describe the development of our model and demonstrate its application at two very different locations: The permafrost-affected landscape of the Barrow Environmental Observatory research reserve on the North Slope of Alaska, and the Walker Branch Watershed on the U.S. Department of Energy's Oak Ridge Reservation, located in the humid subtropical environment of the Valley and Ridge Appalachians of East Tennessee.