A contour may be defined as a line of intersection of a level surface with the surface of the ground. This means every point on the contour line has the same altitude as that of the assumed intersecting surface.
The process of tracing contour lines on the surface of earth is called contouring. A contour map gives the idea of the altitudes of the surface features as well as their relative positions in a plan.
Uses of Contour Maps
- A civil engineer studies the contours and finds out the nature of the ground to identify.
- Suitable site for the project works to be taken up.
- By drawing the section in the plan, it is possible to find out profile of the ground along that line. It helps in finding out depth of cutting and filling, if formation level of road/railway is decided.
- Intervisibility of any two points can be found by drawing profile of the ground along that line.
- The routes of the railway, road, canal or sewer lines can be decided so as to minimize and balance earthworks
- Catchment area and hence quantity of water flow at any point of nalla or river can be found. This study is very important in locating bunds, dams and also to find out flood levels.
- From the contours, it is possible to determine the capacity of a reservoir.