Hi John,

I assume that you want to this for BATS simulation, after you create your domain specifications using "terrain" go to input directory you will find a file named Something_LANDUSE. Something = the name of your simulation. The file is a text file which contains the description of the land use. You can change there, just try to figure out the right place.

Another way, I haven't done it my self but you could try it, before you run terrrain, go to the directory DATA/SURFACE, where you have the surface data and try to impose the changes you want in the file GLCC_BATS_30s.nc and then create your terrain and follow up the rest of the steps. 

Peace