I am performing watershed/drainage analysis using the Hydrology-Spatial Analyst toolset. I have a 2m DEM created from LIDAR for a portion of the area and ~18m DEM (freely available from GeoBase) for the surrounding area. I have tried simply using the Mosaic to New Raster tool to merge the 2 DEMs together. However, problems arise in the hydro analysis due to elevation discrepencies at the edge between the 2 surfaces. For example, there might be a 2m drop in elevation at the boundary between the 2 DEMs which will obviously cause problems with flow direction.
Has anyone encountered this type of issue and if so, what is the proper workflow to correct it?
Thank you!
Lisa
