Tutorial: Process groundwater data in QGIS

4. Define the study area

4.1. Select a feature by expression

The first step is to select the Shire Valley Alluvial Aquifer from the aquifers layer.

1. Click right on the aquifers layer in the Layers panel and choose Open Attribute Table.

2. Click the Select features using an expression button .

3. In the Select by Expression dialogue expand in the middle of the window Fields and Values and double click on AQ_NAME. This will add "AQ_NAME" to the expression on the left side of the window. Then click to add = to the expression. Now on the right side click the button and search the list that appears for Shire Valley Alluvial Aquifer. Double click on Shire Valley Alluvial Aquifer to add it to the expression, which is now:

"AQ_NAME" = 'Shire Valley Alluvial Aquifer"

Select aquifer expression

This means: select from the field AQ_NAME (field names are in double quotes) the Shire Valley Alluvial Aquifer feature. Features are in single quotes.

4. Click to select the feature based on this expression.

5. Click Close to close the dialogue.

6. Close the attribute table.

In the map canvas you can now see the selected aquifer with a yellow boundary. Selections are yellow by default in QGIS.

Now we're going to export the Shire Valley Alluvial Aquifer.