HEC-HMS
FreeVerified
The US Army Corps standard for rainfall-runoff modelling — event and continuous simulation, free to use.
Hydrology & Catchment AnalysisActiveHEC-HMSSCS Curve Number
CROPWAT
DormantFAO's classic tool for crop water requirements and irrigation scheduling from climate and crop data.
by FAO
- Pricing
- Free
- License
- FAO freeware
- Commercial use
- Permitted
- Ecosystem
- Standalone
- Platform
- Windows
About CROPWAT
CROPWAT is the FAO's decision-support tool for irrigation: it computes reference evapotranspiration (FAO-56 Penman-Monteith), crop water requirements through the growing season, and irrigation schedules under different supply assumptions, using climate data from the companion CLIMWAT database or your own records.
The software itself is old Windows freeware, but the methodology is the global standard for irrigation planning, and CROPWAT remains the reference implementation officials and lenders recognise. For scripted workflows, modern packages (pyet for ET, AquaCrop-OSPy for yield response) cover the same ground programmatically.
Where it fits in the workflow
TerrainCatchmentRainfallRunoffRoutingHydraulicsMappingReporting
Alternatives to CROPWAT
Other hydrology & catchment analysis tools covering similar workflow stages.
Browser-based rainfall frequency analysis — fit and rank 11 distributions with confidence intervals.
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HEC-ResSim
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Reservoir system simulation from HEC — operating rules, flood control and multi-reservoir networks, free.
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HEC-SSP
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Statistical hydrology from HEC: Bulletin 17C flood frequency, volume-duration and general frequency analysis.
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HydroMT
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Deltares' Python framework that builds ready-to-run hydrological models from global and local datasets.
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MIKE SHE
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DHI's integrated hydrological model — coupled overland, unsaturated, groundwater and channel flow.
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