Free water engineering tools

Esri's free hydrology framework for ArcGIS Pro — terrain preprocessing and the data model behind many agency workflows.

ETH Zurich's free 2D hydraulics and morphodynamics simulator — rivers, sediment and hazard mapping.

The standard 2D reservoir and stratified-river water-quality model — temperature, DO and eutrophication.

FAO's classic tool for crop water requirements and irrigation scheduling from climate and crop data.

Deltares' operational forecasting platform — the shell running national flood-forecast centres worldwide.

Rapid flood modelling in the browser — steady-state inundation estimates in seconds, anywhere on earth.

Browser-based rainfall frequency analysis — fit and rank 11 distributions with confidence intervals.

Click anywhere on earth, get the upstream watershed in seconds — free delineation in the browser.

The US Army Corps standard for rainfall-runoff modelling — event and continuous simulation, free to use.

The world's most used hydraulic model: free 1D/2D river analysis, sediment, water quality and flood mapping.

Reservoir system simulation from HEC — operating rules, flood control and multi-reservoir networks, free.

Statistical hydrology from HEC: Bulletin 17C flood frequency, volume-duration and general frequency analysis.

The global hydrography reference — basins, river networks, lakes and hydro-environmental attributes, free.

CUAHSI's platform for sharing hydrological data and models — DOIs, collaboration and linked compute.

Free Spanish 2D hydraulic model — flow, turbulence, sediment and habitat modules behind a full GUI.

CDM Smith's free rainfall statistics and STORM-method screening model — IDF analysis, disaggregation, CSO planning.

Model-independent parameter estimation and uncertainty analysis — the calibration standard for groundwater models.

The classic river water-quality model — DO, nutrients and algae along a 1D stream network.

The US Bureau of Reclamation's free 2D river model — FHWA's preferred engine for bridge hydraulics.

The Watershed Bounded Network Model — free Australian runoff-routing hydrology for flood estimation.

Free web tool for building synthetic design-storm patterns — 560+ temporal patterns, exportable to SWMM and HMS.

Programmatic access to ERA5 and the Copernicus Climate Data Store — the world's reanalysis workhorse.