Information

What is "HexWatershed"?

HexWatershed is a mesh independent flow direction model for hydrologic models.

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;

4. It cannot be coupled with other unstructured mesh-based models such as the oceanic models.

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 rewrote all the core watershed delineation algorithms on a completely different data structure.

What is the current status of "HexWatershed"?

We are adding more features to the HexWatershed ecosystem:

• The zonal resampling within the unstructured mesh is supported and other geostatistics are supported as well;

• HexWatershed is ready for continental and global scale simulation (e.g., through the MPAS mesh);

• HexWatershed uses the state-of-art topology method to conduct stream burning and depression filling;

• We are evaluating hydrology simulations using the HexWatershed routing maps.