Information

What is "HexWatershed"?

HexWatershed is a hydrologic routing model based on the hexagon/unstructured mesh framework.

Why do we develop HexWatershed?

Spatial discretization is the cornerstone of all spatially-distributed numerical simulations including watershed hydrology. Traditional square grid spatial discretization has several limitations:

  1. It cannot represent adjacency uniformly;

  2. It leads to the "island effect" and the diagonal travel path issue in D8 scheme;

  3. It cannot provide a spherical coverage without significant spatial distortion.

Therefore, we developed a watershed delineation model (HexWatershed) based on the hexagon mesh spatial discretization.

We further improve HexWatershed to fully unstructured mesh-based to support variable-resolution meshes such as the MPAS mesh.

We propose that spatially distributed hydrologic simulations should consider using a hexagon grid spatial discretization.

How we did it?

We basically rewrote all the core watershed delineation algorithms, just on a completely different data structure.

What is the current status of "HexWatershed"?

We are finalizing a few core components in the HexWatershed ecosystem:

  • A special designed resampling tool for HexWatershed will be available soon;

  • HexWatershed is ready for continental and global scale simulation;

  • HexWatershed is supporting MPAS mesh;

  • We are evaluating hydrology simulations using HexWatershed routing maps.

References:

Chang Liao, Tian Zhou, Donghui Xu, Richard Barnes, Gautam Bisht,

Hong-Yi Li, Zeli Tan, Teklu Tesfa, Zhuoran Duan, Darren Engwirda, and L. Ruby Leung. Advances in hexagon mesh based flow direction modeling. Advances in Water Resources (2021). https://doi.org/10.1016/j.advwatres.2021.104099

Liao, C., Tesfa, T., Duan, Z., & Leung, L. R. (2020). Watershed delineation on a hexagonal mesh grid. Environmental Modelling & Software, 104702. https://doi.org/10.1016/j.envsoft.2020.104702