QGIS
The free, open-source GIS that has become the default spatial platform for water engineers worldwide.
A consistent annual global land cover record at 300m from 1992 — long enough to trend land-use change against.
by European Space Agency (CCI)
ESA CCI Land Cover provides an annual global land cover map at 300m resolution from 1992 to 2015 (continued operationally through the Copernicus Climate Change Service since), built to a consistent methodology specifically so successive years are comparable — a property higher-resolution but sporadically-released products like WorldCover don't offer.
Where WorldCover and Dynamic World win on spatial detail and currency, CCI Land Cover wins on record length: it is the product to reach for when the question is "how has land use in this basin trended over 30 years," not "what is on the ground this month."
Other geospatial & hydro-gis tools covering similar workflow stages.
The free, open-source GIS that has become the default spatial platform for water engineers worldwide.

500+ fast geospatial analysis tools with the best DEM hydrology toolkit in open source.
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.
ESA's TanDEM-X-derived global DEM — the most accurate free global surface model available today.