Contour Analysis | Guide to Surveying and Levelling

Importance of Contouring in the field of Surveying

Contouring is an imaginary line on the ground obtained by joining points having same elevation.

Characteristics of Contours

Contour lines are closed, however they may be close on the map itself or outside the map depending upon the topography.

The spacing between contour lines depends upon the slope of the ground.

In steep slopes, the spacing is small, for gentle slopes the spacing is large.

If the contour lines are equally spaced, they indicate uniform slope.

If the contour lines are parallel, straight or equally placed, they represent plane surface.

In a series of contour lines on the plan or map indicates either a hill or depression.

In case of the hill, the values of the elevation go on increasing towards the centre whereas in case of depression, the values go on decreasing towards the centre.

Uses of Contours

• Selection of suitable site
• Earth work
• Area of drainage basin
• Intervisibility between two points

• Location of a route
• Military operation