Tutorial: GIS for adaptation

4.1. Find open places

• Have a look at the original land-use map (LGN2022_Rotterdam) and check which land-use classes are potentially suitable for developing climate adaptation measures.

Let's assume that the land-use classes 23 (grass in primary built-up areas) and 28 (grass in secondary built-up areas) are potentially suitable. Let's create a a boolean raster that is true for these classes and false for all other classes. We can do this with the Raster Calculator.

1. In the main menu go to Raster | Raster Calculator....

2. Under Raster Bands, double-click on LGN2022_Rotterdam@1 to add it to the expression. Then complete the expression so it states:

"LGN2022_Rotterdam@1" = 23 OR "LGN2022_Rotterdam@1" = 28

Tip: click on the operators instead of typing them.

• Why do we use OR and not AND?

3. Save the result in the project folder and call it open.tif.

4. Click OK.

• The result is a boolean raster. Which renderer do we use to style a boolean raster?

5. Go to the Layer Styling panel and make sure the open layer is active.

6. Use the Paletted/Unique values renderer and click Classify.

7. Change the Color for 0 to red and change the Label to Not open. In the same way, change the Color for 1 to green and change the Label to Open.

Now we see in green all the open patches in the city (based on our simple assumption).

However, we do not distinguish individual patches. Let's fix that in the next section.