[GRASS-user] raster reclassification or map calculator to simulate past sea-level change

[Maris Nartiss]

Hello Erik,
try this in r.mapcalc:
new_dem = if(old_dem < 25, null(), old_dem)

old_dem – name of map with input DEM;
null() – value to assign to cells below 25 (could be 0 too).

Keep in mind – your approach will put under water everything below a
specified level even if there is a natural or artificial dam
preventing water from intruding into the area. Use r.lake to perform
floodfill instead of simple water level rise (be ware – could be
memory hungry on large coputational regions).
Second thing – AFAIK Norway is experiencing intensive GIA. Thus simply
playing around with water level on dem is really primitive way how to
reconstruct palaeoenvironment or predict long term future.

Good luck,
Māris.