There are two important aspects of terrain analysis that are not handled in the methodology described by class Exercise 2 above or by the Watershed Delineation Application. A simple methodology for burning-in streams is to rasterize the digitized stream network and then assign all stream cells a value of zero while maintaining the elevation of land surface cells. Burning streams is a very useful technique for identifying stream locations in flat areas where high resolution DEMs are not available, but this technique should be used with caution. Filling pits is typically the first processing step taken after a DEM is projected into the chosen map projection. Pits are cells or groups of cells which are completely surrounded by cells of higher elevations.
Some pits are artificial while others represent real inland drainage basins.
It is sometimes difficult to distinguish between real pits and artificial pits automatically by using the DEM alone. Two criteria that are useful for identifying real pits are the pit depth and area. I will post information on my web site about when and where the final version of the AV3 Delineation Application can be obtained. Other questions regarding this application should be directed to Dean Djokic or Zichuan Ye. These materials may be used for study, research, and education, but please credit the authors and the Center for Research in Water Resources, The University of Texas at Austin.