New Meshing Strategy Reduces Computing Usage and Enables Modeling of Narrow River Channels

The Science

Stream channels are vital regions where water, nutrients, sediments, and energy from hillslopes converge, supporting diverse ecosystems. Large-scale watershed models struggle to accurately represent these narrow, dynamic regions without requiring highly detailed mesh and excessive computational power. A team of researchers introduced a novel stream-aligned meshing technique that effectively models stream channels, resulting in realistic inundation patterns near streams and rivers. This method maintains the accuracy of a highly detailed mesh while reducing computational cost.

The Impact

This research addresses the critical problem of balancing accuracy and computational efficiency in modeling of large or entire watersheds. A team from Oak Ridge National Laboratory (ORNL) developed a meshing technique that significantly reduces computational costs while maintaining accuracy. Resolving the stream corridor with stream-aligned meshing achieves more realistic flow, inundation, and connectivity patterns in the stream network. This advancement unlocks new opportunities for representing river-specific hydrodynamics, biogeochemistry, and management infrastructure in broader, basin-scale hydrology models at a lower computational cost, and it also paves the way for understanding basin-scale watershed behavior emerging from intricate stream hydro-biogeochemistry.

Summary

A new study from researchers at ORNL addresses the challenge of accurately representing stream corridors in large watershed models, where traditional methods using triangulated or raster-based meshes require extensive refinement and excessive computational effort. The team developed a new meshing technique that aligns long quadrilateral cells with streams, meshes the remainder of the land surface with a coarser triangle-based mesh, and extrudes vertically to form a 3D mesh. This approach maintains the accuracy of highly refined models while drastically reducing computational resources—achieving a 96.4% reduction in mesh size and a 99.7% reduction in computational costs.

Simulations using the Advanced Terrestrial Simulator demonstrate this technique produces more realistic flow, inundation, and connectivity patterns in the stream network. An optional hydrologic conditioning process, tailored specifically for stream corridor cells, eliminates erroneous obstructions and generates more reliable water depth representations. The method is integrated within the Watershed Workflow tool, a Python-based library for watershed simulation, and significantly enhances the capacity to represent stream processes. By lowering computational costs, the method makes stream-specific hydrodynamics and related processes accessible for large-scale hydrological applications.

Principal Investigator

Scott Painter
Oak Ridge National Laboratory
[email protected]

Co-Principal Investigator

Ethan Coon
Oak Ridge National Laboratory
[email protected]

Program Manager

Paul Bayer
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
[email protected]

Funding

This study was funded by the Biological and Environmental Research program within the U.S. Department of Energy’s Office of Science and is a product of the Interoperable Design of Extreme-scale Application Software (IDEAS)–Watersheds project.

References