Good morning everyone.
What will be the best method to calculate from a DEM and a shapefile with the polygons of communes the total surface of each commune that is below sea level, please?
Thank you in advance for your help!
1- raster calculator (in Spatial Analyst Tools/Map Algebra) with [original DEM] <= 0 which produce a new raster with two categories, one above sea level and another below sea level
2- Tabulate area (in Spatial Analyst Tools/Surface/Zonal/) which calculate the surface of each previous categories within the polygons of the shapefile.
3- in the table created, create a new field for the total surface of the two categories.
4- in the same table, create a new field for the percentage of submerged land with surface of submerged land / total surface. Click on properties on the percent field, then click percentage, then Numeric, then all frequencies are percentage, adjust the number of decimals.
5-Spatial join the table to the original table of the shapefiles of the communes. End