1. Understanding Contours

2. What are Contour Lines
Contours Lines - are imaginary lines that join points of the same height above the datum (points of equal elevation)

4. What are Contour Lines
RL AHD
What is the datum ?

5. What are Contour Lines
RL AHD
What is the datum ?

6. What are Contour Lines
RL AHD
What is the datum ?

7. What are Contour Lines
RL AHD
What is the datum ?

8. Contour Interval
The contour lines represent the height of the land in the form of a Reduced Level above the datum.
Each contour will represent a Reduced Level, so an impression of the shape of the land can be formed the contours must be determined at a regular interval.
This is the Contour Interval.

9. Contour Interval
In this case the contours are at a regular interval of 10m of vertical elevation

10. Contour Interval Each Terrace represents a different Reduced Level
The difference in Vertical height is the contour interval

11. Gentle Slope
Plan View

12. Depressions

13. Top of Hill

14. Using Contours Lets us quickly draw a profile of the landRL RL
Contour Interval
Must be
regular RL RL RL

15. Contour line to each other the steeper the land
The Closer the
Contour line to each other the steeper the land RL RL
Horizontal Distances will be irregular