15 PRINCIPAL CHARACTERISTICS OF CONTOUR LINE

A contour line is an imaginary line which connects points of equal elevation. Such lines are drawn on the plan of an area after establishing reduced levels of several points in the area. The contour lines in an area are drawn keeping difference in elevation of between two consecutive lines constant.

Characteristics of Contours

The principal characteristics of contour lines which help in plotting or reading a contour map are as follows:

1. Contour lines must close, not necessarily in the limits of the plan.
2. The horizontal distance between any two contour lines indicates the amount of slope and varies inversely on the amount of slope.
3. Widely spaced contour indicates flat surface.
4. Closely spaced contour indicates steep slope ground.

   

5. Equally spaced contour indicates uniform slope.

   

6. Irregular contours indicate uneven surface.
7. Approximately concentric closed contours with decreasing values towards centre indicate a pond.

   

8. Approximately concentric closed contours with increasing values towards centre indicate hills.

   

9. Contour lines with U-shape with convexity towards lower ground indicate ridge.
10. Contour lines with V-shaped with convexity towards higher ground indicate valley.

    

11. Contour lines generally do not meet or intersect each other. If contour lines are meeting in some portion, it shows existence of a vertical cliff.

    

12. Contours of different elevations cannot cross each other. If contour lines cross each other, it shows existence of overhanging cliffs or a cave.

    

13. The steepest slope of terrain at any point on a contour is represented along the normal of the contour at that point.
14. Contours do not pass through permanent structures such as buildings.

    

15. A contour line must close itself but need not be necessarily within the limits of the map.