BASINS
Gov-Public
EPA's watershed assessment suite — HSPF continuous watershed-quality modelling with GIS and data access built in.
QUAL2K
DormantThe classic river water-quality model — DO, nutrients and algae along a 1D stream network.
- Pricing
- Free
- License
- Freeware
- Commercial use
- Permitted
- Ecosystem
- Excel/VBA, Fortran
- Platform
- Windows
About QUAL2K
QUAL2K, by Steve Chapra and colleagues, modernised the venerable QUAL2E framework for steady-flow river water quality: dissolved oxygen sag, BOD, nutrient cycling, algae, pH and pathogens along a one-dimensional river, with diel temperature and light. Its transparent, spreadsheet-adjacent implementation made it the standard teaching and TMDL screening model for a generation.
Development has largely wound down (the QUAL2Kw fork from Washington State Ecology added auto-calibration and continued longer), but the methods remain textbook-standard, and for a steady low-flow waste-load allocation it still does the job it always did.
Where it fits in the workflow
TerrainCatchmentRainfallRunoffRoutingHydraulicsMappingReporting
Alternatives to QUAL2K
Ranked by the topics, categories and workflow stages they share with QUAL2K.
CE-QUAL-W2
Free
The standard 2D reservoir and stratified-river water-quality model — temperature, DO and eutrophication.
EFDC+
Freemium
Open-source 3D hydrodynamics and water quality — the EFDC lineage modernised, with a commercial GUI option.
SWAT+
Open Source
The USDA watershed model for land use, sediment and nutrients — continuous simulation at catchment scale.
WASP
Gov-Public
EPA's Water Quality Analysis Simulation Program — eutrophication, toxics and sediment in rivers and estuaries.
WEAP
Freemium
Integrated water resources planning and policy analysis framework for basin-scale supply and demand modeling.