I'm digitizing land use and I want to be able to calculate the land use percentage of area in three different areas (circles). I.e. I want to know the land use percentage in each of the three different circles.

How could I do that effectively?

One problem might be that the circles overlap, but that is intentional so that's part of the question. The image shows the three different circles that are my areas of interest and I will start to digitize every land use category in them.

I will then divide the area of each circle with the land use categories area, but is there some way of delimitate it by each circle?


1 Answer 1


Unfortunately, it is impossible to visualize your attachment. I try to suggest you what I would do.

Try creating a new polygon shapefile in a UTM RS (the unity must be km) and draw the limits of the different land-use areas in the whole region. Pay attention to create a field that will allow you to classify each polygon in accordance to its land-use.

Then, I'd make three different shapefiles for each circle. And use each one of them to crop the land-use shapefile, creating three separated new layers (let's say l-u_circle1, l-u_circle2, l-u_circle3).

Finally, you open the attributes table of each one of the new layers and open the field calculator. You ask it to create a new field and to calculate for each polygon its area. You must look inside the geometry formulas and insert


in the expression field.

At this point, I would open the .DBF file of each of the l-u_circle shapefile in Excel and save it as a new .XLS file.

You will now use the calculated areas of each polygon to make the statistics you need. That means: you sum all the areas for each land-use category and then you calculate the percentage. You can also make a nice diagram to represent the results.


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