INDEX

Assignment 4



1. For this assignment, I downloaded three 15 minute quad Digital Elevation Models (DEMs) of a portion of the Albuquerque area from the New Mexico Resource Geographic Information System program (rgis.unm.edu).
2. I imported the interchange files using the ArcView 8x toolbar in ArcCatalog, and then added the data to a new map in ArcMap.
3. Using the Spatial Analyst Raster Calculator, I mosaiced the three DEMs together so that they appeared continuous. Then I used the "focal mean" expression in the Raster Calculator to fill the cells with no data.
4. I again used the Raster Calculator to create the following expressions in order to delineate the stream network and watersheds in the DEM.

• Calculation 1 (Flow direction) - flowdirection([Albuquerque DEM])
  
• Calculation 2 (Flow accumulation) - flowaccumulation([Calculation 1])
  
• Calculation 3 (Streams with > 1 km² drainage area) - con([Calculation 2] > 278,1)
  
• Calculation 4 (Stream links) - streamlink([Calculation 3], [Calculation 1])
  
• Calculation 5 (Zonal max of flow direction for stream links) - zonalmax([Calculation 4], [Calculation 2])
  
• Calculation 6 (Outlets) - con([Calculation 5] = = [Calculation 2], [Calculation 4])
  
• Calculation 7 (Watersheds) - watershed(Calculation 1], [Calculation 6])

5. The layout above depicts the Albuquerque DEM, as well as a small section of the DEM that shows watersheds and streams with a drainage area greater than 1 km².