Hydrology & Catchment Analysis

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

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

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

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.

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

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

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

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

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

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

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.

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

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

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

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

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

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.

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

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

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

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

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

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.