How to Read Topographical Maps with Contour Lines

Topographical maps are important because they show details about the Earth's surface. One of the main features on these maps is contour lines, which help us see how high or low different areas are.

1. What Are Contour Lines?

• Definition: Contour lines are special lines that connect places that are the same height above sea level.
• Spacing: The space between these lines tells us how steep or flat the land is:
  • Close lines mean steep slopes.
  • Wider lines mean gentle slopes.

2. How to Read Contour Lines:

• Contour Interval: This is the height difference between two contour lines. On Swedish maps, this is usually between 5 and 50 meters.
  • For example, if the contour interval is 10 meters, each line shows a change of 10 meters in height.
• Index Contours: Every fifth line is darker or thicker. This is called an index contour, which makes it easier to see changes in elevation.

3. What These Features Mean:

• Peaks and Valleys:

  • Hilltops are shown by closed loops with no other lines crossing them. The height goes up as the loops get smaller.
  • Valleys look like V shapes that point uphill. The point of the V shows where water comes from.

• Plateaus: These are flat areas that may have slight height changes.

• Depressions: These are shown by lines with small ticks on the inside, indicating areas that are lower in elevation.

4. Analyzing Contour Maps:

• Calculate Steepness: You can find out how steep a slope is by using this formula:

$$\text{Steepness} = \frac{\text{Change in height}}{\text{Distance on the ground}}$$

If the contour lines are 10 meters apart and the distance on the ground is 100 meters, the steepness would be 0.1.

5. Tips for Reading Maps:

• Scale: Check the map scale, which shows how the map distance compares to actual ground distance. For example, a scale of 1:50,000 means that 1 cm on the map equals 50,000 cm (or 500 meters) on the ground.

• Legend and Symbols: Use the map's legend to understand what the symbols and lines mean. This can help you read the map better.

6. Real-Life Uses:

• Hiking and Outdoor Activities: Knowing how the land looks is important for hiking, planning where to go, and safety.
• Urban Planning: Understanding high and low areas helps in building houses, roads, and other projects.

By learning how to read contour lines, students can better understand the land around them, which helps with geography skills and problem-solving!