DEMs are provided at 1 km grid cell size for the entire world and 30 meter cell sizes for the entire United States. Figure 2.2 shows an example of a 30 meter DEM terrain representation in Austin, Texas.
Figure 2.2: 30 Meter DEM
DEMs are used in water resources engineering to identify drainage related features such as ridges, valley bottoms, channel networks, and surface drainage patterns. DEMs are also useful in quantifying subcatchment and channel size, length, and slope. The accuracy of this topographic information is a function of the quality and resolution of the DEM, in addition to the DEM processing algorithms used to extract this information (Garbrecht et al., 1999).
One solution to reduce the errors associated with DEMs, as described by Garbrecht et al. (1999a), is to use a high resolution DEM produced by more