SAGA GIS — The Complete Guide: Free Terrain, Hydrology and Elevation Model Analysis
SAGA GIS (System for Automated Geoscientific Analyses) is an open-source GIS built around analysis rather than map production — which is what separates it from QGIS. It is particularly strong with rasters and elevation models.
SAGA GIS
SAGA Development Team
Advanced spatial analysis, especially on elevation models and terrain.
Get it from the vendorWhat you get
- Terrain — slope, aspect, curvature and landform classification.
- Hydrology — sink filling, flow accumulation, catchment delineation and wetness indices.
- Visibility and radiation — viewsheds from a point and solar radiation over a surface.
- Geostatistics — interpolation and kriging from measurement points.
- Remote sensing — image classification and indices.
How to use it
Many engineers never open SAGA itself: its tools are available in the QGIS processing toolbox (in recent versions through a plugin) and run directly on the open layers. The standalone program is worth opening when you need a tool that QGIS does not expose, or for fast work on large rasters.
Related tools
For more raster and hydrological analysis — GRASS GIS. For LiDAR and elevation models in large files — WhiteboxTools. For basin hydrology after delineation — HEC-HMS.
QGIS
QGIS.org
Open-source GIS for spatial analysis, layer work and map production.
Get it from the vendor
GRASS GIS
OSGeo
GIS with strong raster and terrain analysis — catchments, slope, visibility and elevation models.
Get it from the vendor
WhiteboxTools
Whitebox Geospatial
Hundreds of geospatial analysis tools, especially strong on terrain and LiDAR point clouds.
Get it from the vendor
HEC-HMS
US Army Corps of Engineers
Rainfall-runoff hydrological model — infiltration, unit hydrograph and routing. Pairs with HEC-RAS.
Get it from the vendorThe bottom line
SAGA is a free, powerful toolbox for terrain analysis. Most users will benefit from it through QGIS, without learning a new interface.