Hello.
I want to create a layer with mannings n values on my map. In the manual it seems the only way of doing this is creating a LandUse layer, drawing on polygons manually and assigning them respective mannings n values.
I have a raster file that contains mannings n values for my entire map area and it would be far quicker to extract n values directly from this layer than go through the whole process manually (creating a new land use layer). However, I cannot find an explanation of how to do this anywhere, or if it is possible! Has anyone else tried this? My raster file is not complex and just consists of many shapes with assigned n values (there are only 6 different n values in total on the map). The only alternative I can think of is to trace around these areas and create the LandUse file as in the manual but it will be incredibly time consuming!
Any thoughts would be much appreciated
Many thanks, Kate.
