The Science

Understanding water availability and quality for large-scale surface and groundwater systems requires simulation, and many numerical models have been developed by scientists to address these needs. A suite of common hydrologic benchmark challenges was developed, and seven different modeling teams from the United States and Europe exercised their models to achieve the benchmarks, and thereby to better understand how each of the models and model outputs agree and differ.

The Impact

Model intercomparison benchmark challenges build confidence in the choice of model used for a specific scientific question or application, and they illuminate the implications of model choice because they force modeling teams to better understand the strengths and weaknesses of their own and competing models. This understanding leads to more reliable simulations and improves integrated hydrologic modeling.

Summary

Following up on a first integrated hydrologic model intercomparison project several years ago, seven teams of modelers, including two teams supported by the Interoperable Design for Extreme-scale Application Software (IDEAS) project, participated in a second intercomparison project. Teams met at a workshop in Bonn, Germany, and designed a series of three model intercomparison benchmark challenges. The challenges were designed to focus on different aspects of integrated hydrology, including a hillslope-scale catchment, subsurface structural inclusions and layering, and a field study of hydrology on a small ditch with simple but data-informed topography. Parameters were standardized, but each team used their own model, including differences in model physics, coupling, and algorithms. Results were collected, stimulating detailed conversations to explain similarities and differences across the suite of models. While each of the codes shares a common underlying core capability, each of them is focused on different applications and scales and has its own strengths and weaknesses. This type of effort leads to improvement in all the codes and improves the modeling community’s understanding of simulating integrated surface and groundwater systems hydrology.

Principal Investigator

Ethan Coon
Oak Ridge National Laboratory
coonet@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

Funding was provided by the Subsurface Biogeochemical Research program (SBR) of the Office of Biological and Environmental Research (BER), within the U.S. Department of Energy (DOE) Office of Science, and the Interoperable Design for Extreme-scale Application Software (IDEAS) project of the DOE Advanced Research Projects Agency-Energy (ARPA-E).

References