Watershed Delineation GIS Checklist

Watershed boundaries from a DEM are sensitive to sinks, outlet placement, and stream burning. The final boundary should be checked against maps and field logic.

1. Use an appropriate DEM

Select a DEM resolution that matches the project scale. Very coarse DEMs can miss small diversion channels and local ridges.

2. Fill sinks carefully

Run sink filling, but review flat areas because aggressive filling can modify drainage paths.

3. Snap the outlet

Place the outlet on the derived stream line, not just visually near the river.

4. Compare with known rivers

Overlay stream network, satellite imagery, and topographic maps to verify whether the boundary makes sense.

5. Export with metadata

Record DEM source, date, CRS, sink-fill method, and threshold area used for stream generation.