Assignment 4 – DEM’s and Watersheds

The goal of this assignment was to familiarize ourselves with Digital Elevation Models (DEMs) and their processing utility in creating stream networks and

watershed basins. The data processing for this assignment primarily took place in the Spatial Analyst extension in ArcMap. In order to most effectively

carry out the process of creating these stream networks and watershed delineations, it is important to keep in mind the following list:

• Digital Elevation Model

• Pre-Processing the DEM

• Flow Direction Grid

• Flow Accumulation Grid

•Stream Identification Using a Threshold

• Identify Outlets

• Determine Watershed Boundaries

If each of the above steps is performed satisfactorily (i.e. accurately) then the resultant coverage will display watersheds at a user-defined scale (based on

the conditional threshold) and the associated stream network(s).

The following layout show a representative sample of some of the interim steps that were necessary in to create the final output,

which in this case was a rasterized watershed and stream network (including stream outlets) for the headwaters of the Rio Puerco.

We started with three (3) - 30-meter Digital Elevation Models (DEM) which were mosaiced together. The overall area of study is

a portion of the Middle Rio Grande Valley.