Model:HexWatershed

HexWatershed

Also known as
Model type	Single
Model part of larger framework
Note on status model
Date note status model

Incorporated models or components:

Spatial dimensions	2D
Spatial extent	Global, Continental, Regional-Scale, Landscape-Scale, Watershed-Scale
Model domain	Terrestrial, Hydrology, Coastal, Ecosystems, Cryosphere
One-line model description	A watershed delineation model based on hexagonal mesh grid
Extended model description	HexWatershed is a C++ program to define flow direction and other watershed characteristics at regional to global scale. The unique feature of HexWatershed is that it uses a hexagon and hexagon-alike unstructured mesh. Because of that, it have many advantages: It can represent adjacency uniformly It eliminates ``island effect due to the differences in D4 and D8 neighbor definitions It can effectively represent a spherical topology such as Earth

Keywords:	Watershed delineation, Unstructured, hydrology, flow routing, Hexagon,

Name	Chang Liao
Type of contact	Model developer
Institute / Organization	Pacific Northwest National Laboratory
Postal address 1
Postal address 2
Town / City	Richland
Postal code	99354
State	Washington
Country	United States
Email address	chang.liao@pnnl.gov
Phone
Fax

Supported platforms	Unix, Linux, Mac OS
Other platform
Programming language	C++
Other program language
Code optimized	Single Processor, Multiple Processors
Multiple processors implemented	Shared memory
Nr of distributed processors
Nr of shared processors	20
Start year development	2017
Does model development still take place?	Yes
If above answer is no, provide end year model development
Code development status	Active
When did you indicate the 'code development status'?	2020
Model availability	As code, As teaching tool
Source code availability (Or provide future intension)	Through web repository
Source web address	https://github.com/pnnl/hexwatershed
Source csdms web address
Program license type	GPL v3
Program license type other
Memory requirements	Depend on study domain and spatial resolution
Typical run time	Depend on study domain and spatial resolution, a few minutes for a typical watershed.

Describe input parameters	DEM raster and Hexagon shapefile, stream segment threshold
Input format	ASCII
Other input format	Input and output workspace, etc.
Describe output parameters	Hexagon DEM, flow direction, flow accumulation, stream grid, stream segment, stream order, stream confluence, subbasin, watershed boundary, etc.
Output format	ASCII, Binary
Other output format	NetCDF and VTK
Pre-processing software needed?	Yes
Describe pre-processing software	QGIS may be needed to generate the hexagon mesh grid shapfile.
Post-processing software needed?	No
Describe post-processing software
Visualization software needed?	Yes
If above answer is yes	ESRI
Other visualization software	VisIt if use the version 2.0

Describe processes represented by the model	DEM resampling; Depression filling; Flow direction; Flow accumulation;
Describe key physical parameters and equations	Terrain analysis. One equation is the resolution of a hexagon can be estimated using its area instead of edge length.
Describe length scale and resolution constraints	It is best performance for high resolution (<100m) simulation. With the version 2.0, coarser resolution is supported through stream burning feature.
Describe time scale and resolution constraints	None
Describe any numerical limitations and issues

Describe available calibration data sets	National Hydrography Dataset (NHD) flowline datasets were used to evaluated the model.
Upload calibration data sets if available:	Media:Please refer to the paper
Describe available test data sets
Upload test data sets if available:
Describe ideal data for testing

Do you have current or future plans for collaborating with other researchers?	Yes, I plan to use this model with other hydrology models, both regional and global scale.

Is there a manual available?	Yes
Upload manual if available:	Media:The manual will soon available online
Model website if any	https://www.hexwatershed.org
Model forum / discussion board	We currently use Github issue for discussion. https://github.com/pnnl/hexwatershed

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Model info

Authors

Zhou

Source code

Model citations

Other models by author

Featured publication(s)	Year	Model described	Type of Reference	Citations
Liao, Chang; Tesfa, Teklu; Duan, Zhuoran; Leung, L. Ruby; 2020. Watershed delineation on a hexagonal mesh grid. Environmental Modelling & Software, 128, 104702. 10.1016/j.envsoft.2020.104702 (View/edit entry)	2020	HexWatershed	Model overview	12
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