Modeling Across Multiple Scales to Enable System-Level Understanding of a Watershed

Novel model structures allow advanced models of permafrost thermal hydrology to run at scale.

The Science

Field and laboratory observations and the models that are used to help understand the observed processes typically focus on relatively small scales, but the consequences of those processes must be evaluated at larger watershed or regional scales. An intermediate-scale modeling approach has been developed to bridge this gap in scales and improve confidence in simulations of Arctic hydrology and permafrost dynamics.

The Impact

Broadly applicable to hydrology modeling, the approach makes it possible to include more detail in process representations, thus providing direct links between detailed field investigations and larger-scale models. The resulting model improves the representation of permafrost dynamics, which directly affect cold-region hydrology, Arctic infrastructure stability, and biogeochemical cycles.

Summary

Motivated by results from fine-scale simulations, scientists from Oak Ridge National Laboratory and Los Alamos National Laboratory developed an intermediate-scale model. The new model replaces a fully three-dimensional (3D) system with a 2D overland thermal hydrology system and a family of 1D vertical columns, where each column represents a thermal hydrology system coupling the surface and subsurface but without lateral flow. This approach accurately approximates the fully resolved solution but can be solved at significantly less computational cost. The computational advantages will enable state-of-the-art models of permafrost dynamics to be applied across large swaths of the Arctic.  Furthermore, the approach supports the broader strategy of using local models and field observations to reduce uncertainty in watershed, regional, and global Earth System Model predictions.

Principal Investigator

Ahmad Jan
Oak Ridge National Laboratory
jana@ornl.gov

Program Manager

Paul Bayer
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
paul.bayer@science.doe.gov

Funding

This work was supported by Interoperable Design of Extreme-scale Application Software (IDEAS) project, through the U.S. Department of Energy (DOE) Advanced Research Projects Agency-Energy (ARPA-E), and by the Next-Generation Ecosystem Experiments (NGEE)–Arctic project, through the Office of Biological and Environmental Research within the U.S. Department of Energy Office of Science.

References

Jan, A., E. T. Coon, S. L. Painter, and R. Garimella, et al. "An intermediate-scale model for thermal hydrology in low-relief permafrost-affected landscapes". Computational Geosciences 22 163–177  (2017). http://doi.org/10.1007/s10596-017-9679-3.