CSDMS 2024: Coastlines, Critical Zones and Cascading Hazards: Modeling Dynamic Interfaces from Deep Time to Human Time

Mesh independent flow direction modeling using HexWatershed 3.0

Chang Liao

Pacific Northwest National Laboratory, United States
Matthew Copper PNNL United States

HexWatershed is a hydrologic flow direction model that supports structured and unstructured meshes. It uses state-of-the-art topological relationship-based stream burning and depression-filling techniques to produce high-quality flow-routing datasets across scales. HexWatershed has substantially improved over the past two years, including support for the DGGRID discrete global grid system (DGGS).

This presentation will provide an overview of HexWatershed, highlighting its capabilities, new features, and improvements. Through hands-on tutorials and demonstrations, attendees will gain insights into the underlying philosophy of the HexWatershed model, and how to use HexWatershed products to run large-scale hydrologic models in watersheds worldwide. Specifically, this tutorial will cover major components in the HexWatershed ecosystem, including the computational mesh generation process, river network representation, and flow direction modeling. We will provide participants with resources to extend the tutorial problems and gain additional familiarity with the tools and workflows introduced.

Attendees are encouraged to bring their laptops with internet access and a functional web browser. Tutorials will involve scripting operations in the Python language, such as Jupyter Notebook. We will use the Conda utility to install dependency libraries and Visual Studio Code to run the notebooks.

Please acknowledge the original contributors when you are using this material. If there are any copyright issues, please let us know ( and we will respond as soon as possible.

Of interest for:
  • Terrestrial Working Group
  • Coastal Working Group
  • Hydrology Focus Research Group
  • Chesapeake Focus Research Group
  • Critical Zone Focus Research Group
  • Human Dimensions Focus Research Group
  • Ecosystem Dynamics Focus Research Group
  • River Network Modeling Initiative