I have a shapefile of a country with the 29 provinces. I also have shapefiles with the areas which are protected from construction (there are 4 categories for protection, within 4 shapefiles. Some of the protected areas belong to more than one category). I have also created a shapefile which is the buffer of the electrical transmission lines.
I would like to work out the area within each province which is maximum 20km from transmission line, minus the protected areas. (This is so I can eventually work out the maximum area available for solar panels.)
I am using QGIS.
My method is like this:
Dissolve the shapefiles for protected areas (as they are broken up by name, etc, but I am not interested in this, only the total area). I have done this by creating a new column ("One") in the attribute table that has the value "1" for each entry and dissolved by this attribute because I cannot figure out a better way. I have then deleted all other attributes since I think they are slowing things up when I am doing other things (maybe this is wrong?)
Merge the 4 dissolved protected areas. With the new layer I dissolve again to get rid of any overlapping features. I am now left with a shapefile of the protected areas which has an empty attributes table.
The next step is where I am getting stuck. This is what I expected to work:
- Clip The protected areas layer by the transmission buffer layer. I hoped that this would leave me with a shapefile that has only the protected areas that lie within transmission line buffer area. However this does not work because the resulting layer has an empty attribute layer and therefore cannot be seen.
What am I doing wrong here?
I would eventually like to: - Create a shapefile of the non-protected area within the transmission buffer area (I expect this would be by using Difference?) - Split this by province (I have tried to use Join by Attribute but it is not working)