I've tried searching through the existing questions but am struggling to find a succinct answer to what I am trying to achieve.
For background, I am running a flood model in TUFLOW to help support a residential development on greenfield land. Part of the site has been shown to flood in a given event and I now want to reprofile areas of the land to allow additional flood storage. The hope is that with the reprofiled land, the flood extents will be greatly diminished and so there will be more land available to the development.
I have drawn polygons in QGIS over the exact areas that will need to be lowered by specific amounts i.e. the land in one area varies from 66.42-66.73m AOD. This will now be a uniform 66.10m AOD.
Is there a way of simply modifying the existing raster DEM file using the polygons?