Contents

Delineation (using GIS)

Here we use QGIS as the tool to delineate a watershed.

Note

The example follows the YouTube video Watershed Delineation in QGIS (Quickest & Easiest Tutorial). If you find this too difficult you may wish to consider a career in Cosmetology.

The fundamental workflow is:

  1. Download DEM file (from National Elevation Dataset or something similar). Then open the file (as RASTER).

  2. Select or accept the CRS (Coordinate reference system)

  3. Designate area of interest.

  4. Pit filling algorithm.

  5. Identify pour point(s).

  6. Delineate using flow-acculumation algorithms.

Where to get data?

For basemaps, OSM (Open Street Maps) is probably sufficient for most uses.

For DEMs:

  1. SRTM (NASA server) has 30-meter resolution, world-wide. Higher resolution for some areas.

  2. Higher resolution (1-meter) from USGS