I am using QGIS 2.18.1 Las Palmas, in Windows 10, and that's the issue I want to clarify:
I've got 2 polygon shapes. 1- One with river basins, and 2- other one with different levels of dessertification risk:
In the attribute tables for each one, I've got names for each river basin in the first map, and in the second one, I've got 5 different levels (differenced by colors in the picture)
So, what I need is not only cut or intersect both of them. What I need is to know which level of dessertification risk is more predominant, within each river basin. In other words, I need a final shape similar as the river basins shape, but with an additional column saying the level of dessertification risk which occupies the biggest % of surface within each basin.
For example: I will zoom into one of the basins, setting the river basins without filling, so you can see the dessertification risk layer behind:
We see different colors within the polygon. Initially, it seems that the most predominant color is purple, or could be the light green.
What I need is to determine which one covers the biggest % of surface within this polygon, and set it as a new value for the river basins polygons.
I've tried different things but I don't find the solution.