I am working with a Digital Elevation Model for the area in and around a small city, attempting to delineate watersheds using the Hydrology tools in the Spatial Analyst extension.
The problem is that there are quite a large number of artificial drainage structures (e.g. storm sewers and culverts), not reflected in the DEM, that are preventing me from getting accurate results.
I think I could improve the accuracy of my watersheds if I could modify the DEM by "re-instating" these drainage channels (I have a vector layer containing the locations of the drainage structures, currently as line features that can easily be buffered and exported as polygons).
Does anyone have any experience doing this (or similar) and would like to share the method they used? I believe it is possible to use the Raster Calculator to modify elevations in a DEM within a specific area using a mask, but I do not have experience with this kind of operation and I have not been able to find any example scripts or tutorials just from searching the web.
Thanks in advance for any help or pointers you might be able to provide.