I have a DEM for a region over which I want to simulate an ecological process. I would like to run several simulations for the same region but I want to alter the topography for the simulations. Most important, I would like to alter the slope (and probably aspect) in various ways. I am working in ArcGIS and I extracted the slope from the DEM but I have not found any way to manipulate the slope or even access the slope values with their coordinates. Running the process requires several other layers so I would like to remain within the parameters (coordinates, datum, ellipsoid, etc.) of the original DEM. Is there a way I can alter the slope output, which is currently a raster? Could I, for example, make the whole region 30% slope with a south aspect? Is there some other way to generate custom slope files that will be consistent with the other layers?
I am using an ArcGRID DEM from the NED. Perhaps a different starting point is more appropriate, such as a contour map?