A contour line is a 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.
Contour maps are extremely useful for various engineering works:
- 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.