I have done this with vector before, but now I have 2 raster layers:

1 raster layer that refers to land use: urban, forest, water, agriculture

1 raster layer that was classified in 3 classes for flood risk: low, medium, high.

What steps I have to do to get a new raster layer of only urban land use which is situated in high flood risk?

And how to find the most land use that is situated inside the high risk zone?

I spent days thinking of this but I don't really have any experience with spatial analysis using rasters.

  • 1
    What research have you done so far on the topic? Have you considered vectorizing the rasters? If so, why didn't you proceed?
    – Erik
    Commented Sep 10, 2019 at 10:21

1 Answer 1


you can reclassify both rasters and sum them. Example: Reclassify Urban to 1 and others to 0. Same for the 2nd layer. High flood 1, others 0. So if you sum rasters the area under 2 value will be both urban and high flood.

For the 2nd question, you reclassify the second layer High flood 1, others NoData. Then Mask the 1st layer to the 2nd and only areas with High Flood will show up.


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