Browse all tools

JAXA's 30m global DSM from PRISM stereo imagery — a strong third opinion alongside SRTM and Copernicus DEM.

Open-source 2D shallow-water modelling in Python from Geoscience Australia — strong for dam break and tsunami.

EPA's aquatic ecosystem model — fate and ecological effects of nutrients, toxics and stressors together.

The official portal for Australian Rainfall & Runoff design inputs — losses, temporal patterns and preburst.

Near-real-time scatterometer soil moisture from EUMETSAT — hours of latency, useful for operational monitoring.

A 30m global DEM reaching to 83° latitude — the go-to where SRTM/NASADEM have no coverage at all.

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.

EPA's watershed assessment suite — HSPF continuous watershed-quality modelling with GIS and data access built in.

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

Gauge-blended satellite rainfall at 0.05°, daily, since 1981 — the standard for drainage work in data-sparse regions.

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

GPU reimplementation of the CaMa-Flood global river routing model — continental flood simulation on PyTorch/Triton.

The open global large-sample hydrology dataset — thousands of catchments with forcing, attributes and streamflow.

ESA's TanDEM-X-derived global DEM — the most accurate free global surface model available today.

QGIS plugin for exploring mesh model results — animate TUFLOW, Telemac and HEC-RAS 2D outputs in the GIS.

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

Deltares' open flexible-mesh suite for rivers, estuaries and coasts — hydrodynamics to morphology.

Browser-based hydrology and hydraulics calculators for practising engineers — no install, report-ready output.

Near-real-time 10m land cover from Google/WRI, updated every Sentinel-2 pass — land cover that keeps up.

Open-source 3D hydrodynamics and water quality — the EFDC lineage modernised, with a commercial GUI option.

USGS R package for long-term water-quality and streamflow trends — home of the WRTDS method.

EPA's free tool for estimating site runoff reduction from green infrastructure, with climate scenarios.

EPA's toolbox for sanitary sewer overflow planning — RDII analysis with the SWMM engine underneath.

The public-domain engine of urban drainage: dynamic-wave pipe networks, runoff, LID and water quality.

The public-domain standard for water distribution modelling — hydraulics and water quality in pressurised networks.

Full MATLAB control of the EPANET engine — the standard bridge for control and optimisation research.

Multi-species water quality for EPANET — model chloramine decay, DBPs and reactive chemistry in networks.

ECMWF's hourly global reanalysis — the default gap-free climate forcing record for ungauged catchments worldwide.

A consistent annual global land cover record at 300m from 1992 — long enough to trend land-use change against.

The longest satellite soil moisture record available — merged active+passive retrievals back to 1978, free, no login.

Global 10m land cover from Sentinel-1/2 — the highest-resolution free global land cover map available.

Copernicus DEM with forests and buildings stripped out — the bare-earth DEM flood and drainage models actually want.

DHI's finite-element groundwater platform — unstructured meshes, density-driven flow, heat and mine dewatering.

A free bundle of FHWA drainage calculators: channels, weirs, curb & gutter, riprap, detention and more.

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

The Python interface to MODFLOW — build, run and post-process groundwater models entirely in code.

Jacobs' 1D/2D river and floodplain suite — a UK practice staple with a genuinely useful free tier.

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

NASA's 30-minute, 0.1° global precipitation record — the highest time resolution of any satellite rainfall product.

Monthly total water storage change from satellite gravity — the only direct signal of large-scale groundwater depletion.

GRASS GIS

Open Source

Four decades of geospatial engineering — r.watershed and the most battle-tested hydrology modules in GIS.

Build and read EPA SWMM models as QGIS layers — free GIS-based SWMM model construction.

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

Planetary-scale geospatial analysis in the cloud — the data catalogue and compute behind modern water remote sensing.

Veteran commercial MODFLOW GUI with deep PEST integration — a consultant favourite for calibration-heavy work.

Jupyter notebook suite for batch HEC-RAS and HEC-HMS runs — parallel execution and calibration statistics.

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.

FHWA's free culvert analysis program — the reference implementation of HDS-5 culvert hydraulics.

The standard for vadose-zone modelling — variably saturated flow and transport by Richards' equation.

A Python software stack for US hydrology data: NHD+ networks, gauges, DEMs, soils and climate via one API family.

Environmental data management and 3D visualization software for hydrogeologists and site investigation teams.

The US land-development standard for TR-55/TR-20 hydrographs and detention pond design.

Deltares' Python framework that builds ready-to-run hydrological models from global and local datasets.

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.

Autodesk's ArcGIS Pro-native distribution modelling — for utilities whose network data lives in Esri.

Autodesk's integrated catchment model — the heavyweight for large sewer networks and coupled 2D flooding.

Pixel-level surface water history since 1984, built from the entire Landsat archive — where water has been, and when.

The Bristol raster flood model behind global flood maps — open source with GPU-accelerated solvers.

NASA's satellite-era atmospheric reanalysis — hourly global fields from 1980, the default alternative to ERA5.

DHI's integrated hydrological model — coupled overland, unsaturated, groundwater and channel flow.

DHI's unified platform for rivers, urban drainage and distribution networks — successor to MIKE 11/MIKE URBAN.

The USGS groundwater model — the world standard for aquifer simulation, rebuilt as a modular multi-model framework.

Global actual ET from MODIS, 500m, 8-day/monthly/annual — a Penman-Monteith water-balance term, ready-made.

1km daily/8-day land surface temperature from MODIS — the standard thermal input for energy-balance ET and snowmelt.

250m, 16-day global vegetation index composites — the standard input to crop-coefficient ET and drought indices.

500m daily/8-day global snow-cover extent from MODIS — the standard optical snow product for basin-scale tracking.

USGS particle tracking for MODFLOW — pathlines, travel times and capture zones from flow solutions.

Precipitation that optimally blends gauges, satellites and reanalysis at every grid cell — 3-hourly, 0.1°, global.

Multi-species solute transport for MODFLOW — advection, dispersion, sorption and reactions in aquifers.

eWater's stormwater-quality model — the WSUD assessment standard across Australian councils.

MATLAB (and Python/LabVIEW) co-simulation with SWMM — built for real-time control research.

A STAC API and Jupyter environment over petabytes of satellite data — Sentinel, Landsat, MODIS, ERA5, CHIRPS and more.

The USGS's free graphical interface for MODFLOW — grid-independent model design without a commercial GUI.

The unified search portal across every NASA Earth-observation archive — SRTM, MODIS, SMAP, GPM, GRACE and more.

SRTM reprocessed with modern algorithms and merged with ASTER/ICESat — a quiet accuracy upgrade, same footprint.

Neyman-Scott stochastic rainfall generation in Python — synthetic series and disaggregation, single or multi-site.

The US precipitation-frequency standard — point rainfall depths for any duration and return period, free.

NCEP's coupled atmosphere-ocean-land reanalysis, sub-daily, 1979–present — strong where ocean coupling matters.

Transform elevations between vertical datums — the essential fix-up for US coastal flood and drainage models.

Free viewer and exporter for NEXRAD radar, satellite and climate data — out to GeoTIFF, Shapefile and NetCDF.

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

Deep-learning rainfall-runoff modelling — the LSTM framework behind much of ML hydrology research.

An open-source take on Google Flood Hub — per-gauge neural network streamflow forecasting you can self-host.

Bentley's transient analysis package — the commercial standard for surge studies on pumping mains.

Bentley's sanitary and combined sewer modelling suite, integrated with CAD and GIS environments.

Bentley's flagship distribution suite — design, optimisation and criticality on EPANET-compatible hydraulics.

CHI's commercial GIS front-end for SWMM — the most direct productivity upgrade for serious SWMM users.

A neural-network satellite rainfall climate data record, daily, 0.25°, purpose-built for long-term trend studies.

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

USGS geochemical modelling — speciation, batch reactions, 1D reactive transport and inverse modelling.

USGS Precipitation-Runoff Modeling System — distributed continuous simulation with strong snow physics.

Time-series analysis of groundwater heads in Python — transfer-function models instead of full aquifer simulation.

USGS software for Bulletin 17C flood-frequency analysis of annual peak-flow records.

Python interface to the SWMM engine — step through simulations, read state, and control gates in real time.

Python water-resource network simulator — fast LP-based allocation for reservoir systems and supply networks.

QGIS

Open SourceVerified

The free, open-source GIS that has become the default spatial platform for water engineers worldwide.

A QGIS plugin that turns the free GIS into a water-network modelling environment for EPANET.

The QGIS interface for SWAT+ — delineate, discretise and build a watershed model without leaving the GIS.

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

Python automation for HEC-RAS 6.x: batch runs, parallel execution and HDF results extraction.

Stochastic storm transposition in Python — probabilistic extreme rainfall scenarios from remote-sensing data.

A flexible hydrological modelling framework — emulate GR4J, HBV, HMETS or build your own model structure.

High-performance DEM conditioning — Priority-Flood depression filling at scale, C++ with Python bindings.

SAGA GIS

Open Source

The geomorphometry powerhouse — hundreds of terrain and hydrology modules behind a free desktop GIS.

Deltares' reduced-complexity compound flood model — coastal, fluvial and pluvial drivers in one fast solver.

NASA's L-band radiometer soil moisture mission — 9km/36km near-surface moisture, daily, since 2015.

NOAA's modelled snow depth and SWE for the CONUS — 1km daily grids from satellite, airborne and station data.

The reference R implementation of SPEI and SPI from the index's own authors.

Python toolbox for calibrating and uncertainty-analysing any environmental model — SCE-UA, DREAM, GLUE and more.

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

The original free global DEM — 30m/90m elevation from an 11-day shuttle radar mission, still a baseline today.

USGS operational ET at Landsat resolution — 30m actual evapotranspiration for water-rights and irrigation accounting.

The USDA watershed model for land use, sediment and nutrients — continuous simulation at catchment scale.

EPA's Climate Adjustment Tool for SWMM — apply downscaled climate projections to rainfall and evaporation inputs.

Free 10-20m multispectral imagery, 5-day revisit — the imagery backbone under WorldCover and Dynamic World.

Dewberry's open tool for building STAC catalogs of storms and gauge data — inputs for stochastic storm transposition.

Open-source water hammer simulation in Python — method-of-characteristics transients on EPANET networks.

Benchmark-setting commercial 1D/2D flood engine with GPU acceleration — dominant in AU/UK flood studies.

Utah State's parallel terrain-analysis suite — D-infinity flow modelling and objective stream-network extraction.

Analytic element groundwater modelling in Python — multi-layer steady flow with no grid at all.

USGS's merged surface-water and groundwater statistics program — baseflow separation, flow duration, low flows.

USGS web tool for basin delineation and regression-based flow statistics at any US stream point.

The Variable Infiltration Capacity model — macroscale land-surface hydrology for big basins and climate studies.

Virginia DEQ's official Excel workbooks for stormwater compliance via the Runoff Reduction Method.

EPA's Water Quality Analysis Simulation Program — eutrophication, toxics and sediment in rivers and estuaries.

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

Sandia/EPA's Python toolkit for water network resilience — EPANET simulation plus disaster scenarios and metrics.

Deltares' distributed hydrological model in Julia — gridded rainfall-runoff with kinematic-wave routing.

WhiteboxTools

Open SourceVerified

500+ fast geospatial analysis tools with the best DEM hydrology toolkit in open source.

NRCS's official implementation of TR-55 small-watershed hydrology: peaks, hydrographs and storage.

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

INRAE's GR rainfall-runoff models (GR4J family) plus CemaNeige snow, packaged for R.

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

Reference Python implementations of SPI, SPEI and Palmer indices for drought monitoring.

The USGS R package for pulling NWIS and Water Quality Portal data — gauge records as tidy data frames.

Fast global watershed delineation in Python — the MERIT-Hydro engine behind the Global Watersheds web app.

Statistical downscaling and bias correction of climate projections in R — part of the climate4R framework.

EPANET in the browser — build, import and run distribution models on a map with zero installation.

Canadian government R package for streamflow analysis — trends, frequencies and summaries from HYDAT.

Python + Google Earth Engine without the pain — interactive mapping and analysis of petabyte-scale water data.

Python automation for HEC-HMS — batch and parallel runs, design storms, and DSS handoff to HEC-RAS.

R workhorse for hydrological time series — aggregation, summaries and hydrologically-aware plots in a few calls.

A tiny Python package that computes NSE, KGE and friends correctly — the metrics layer of model evaluation.

A friendly Python client for USGS NWIS streamflow data — request, cache and plot gauge records in a notebook.

EDF's open-source finite-element suite for free-surface flow — 2D/3D rivers, estuaries, waves and sediment.

Python framework for PEST/PEST++ workflows — programmatic setup, ensembles and uncertainty analysis.

Python control and post-processing for 2D hydraulic models — SRH-2D and HEC-RAS 2D results to VTK and beyond.

Reference and potential evapotranspiration in Python — 20+ published methods, FAO-56 included, on pandas/xarray.

Build RORB, WBNM and URBS model files straight from GIS shapefiles — with companion QGIS plugins.

Watershed delineation in pure Python — DEM conditioning to catchment boundary in a dozen lines.

Benchmark scenarios for smart-stormwater control — test real-time control algorithms on curated SWMM systems.

Read HEC-RAS HDF5 geometry and results into GeoPandas/xarray — built for FEMA's flood-risk data pipelines.

R client for the UK National River Flow Archive — catalogue, gauged daily flows and catchment metadata.

Pure-Python reading, editing and running of SWMM INP, RPT and OUT files — the full file-format toolkit.

Pandas-powered reading, editing and version-diffing of SWMM models — the model-management side of the stack.

Run and read EPA SWMM from R — model execution, results import and GIS conversion on CRAN.

Python CLI and library for extracting time series from SWMM binary output files.

The open library for weather-radar rainfall processing — from raw volumes to engineering-ready rainfall fields.

Climate indices and bias adjustment on xarray — the operational-grade library for climate-data engineering.