Goal: In this lesson you will build upon maps created in Activity 1. These maps will help answer questions about the interrelationships of the physical and human environment of Africa by examining relief, precipitation, and population data.
GIS Skills Involved: Symbolization and spatial queries.
Materials: To complete this lesson you will need ArcGIS software and the Africa Lesson data (Download the Data for Activities 1-3).
Step 1. Let's look at population distributions in Africa. Open the ArcMap project you saved in Activity 1 using the File menu, then navigate to your folder and open Relief.mxd.
Step 2. Select the Add Data tool and add cities.shp.
Make the cities layer visible by checking the box.
Step 3. Double click on the cities.shp layer to access the Layers Properties and click on the Symbology tab. Click on "Quantities" and select "Graduated Symbols." Under Value Field, select "Population." Click on the "Template" box to open the Symbol Selector and choose the symbol that is a circle with a dot in the middle, and change the color to a light green. Finally, change the size range of your cities symbols from 2 to 24. Click OK and close the layer properties.
Step 4. Answer these questions using this map setup:
A) In which relief area (ex: Glaciers, High Mountains, etc) are the largest number of cities located? Why?
B) In which relief area are the fewest number of cities located? Why?
Step 5. The real power of GIS is to be able to answer geographic questions.
Let’s perform a simple query to find the cities with the largest populations in Africa. At the top of the screen click "Selection" —> "Select by Attributes". Make sure Cities is the layer selected, then double-click "Population" and click on the greater than (>) symbol. Click the "Get Unique Values" button and scroll down to 3000000 and double-click on it. Click Apply and close the Select by Attributes box. Notice that the selected cities now appear in blue. These are the cities with a population over 3,000,000.
Step 6. Use the Identify tool to click on the highlighted cities one by one.
C) Identify the cities with populations over 3,000,000. List them by name and population below:
Step 7. Repeat steps 2 and 3 but this time using Precip.mxd you made in Activity 1. If you don't have the Precip view, create it using the directions from Activity 1.
D) In which precipitation areas are the least number of cities located (areas of low precipitation or high precipitation)?
Step 8. Repeat steps 2 and 3 but this time using Climate.mxd you made in Activity 1.
E) Do you think climate has an effect on city size? Why or why not?
Save your map and exit ArcGIS.
*** End of Africa Activity 2 for ArcGIS ***
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