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.

Water quality data management, geochemical plotting, and statistical analysis software for hydrogeologists.

Pumping, slug, and packer test analysis software for hydrogeologists to calculate aquifer hydraulic properties.

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.

Storm and foul water drainage design and 1D hydraulic modelling software for UK and Irish civil engineers.

Browser tool for estimating point terrain elevations globally by address, coordinates, or map click.

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.

Browser-based urban stormwater and drainage modeling powered by OpenSWMM 6 compiled to WebAssembly.

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.

A modern Python interface for HEC-RAS project parsing, simulation automation, and result visualization.

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.

3D groundwater flow and transport modeling environment for MODFLOW, SEAWAT, and PEST calibration workflows.

Hydrologic modeling software for urban and rural stormwater management, master drainage planning, and pond design.

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.

Integrated water resources planning and policy analysis framework for basin-scale supply and demand modeling.

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.