Geospatial & Hydro-GIS

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

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.

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.

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

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

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.

GRASS GIS

Open Source

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

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.

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

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

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

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

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.

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

QGIS

Open SourceVerified

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

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

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.

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

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

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

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

WhiteboxTools

Open SourceVerified

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

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

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

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