what is contour and their use

Upendra Kumar

10 m interval contour

The line of intersection of the level surface with the surface of the ground is called contour line. or the imaginary line joining at the same elevation above the datum surface. A level surface is a curved surface that has every point on which is equidistant from the center of the earth. A level line is a line on a surface at all the points.

Contour Interval:-The vertical distance between any two consecutive contours is called contour interval.

Horizontal Equivalent:-The horizontal distance between any two consecutive contours is called horizontal equivalent.

Uses of contour

1. In civil work-(a) For information about the tract of the region, which is flat, undulating or mountainous, etc.

(b) For observation of suitable areas for engaging works, Such as reservoir, canal, sewer line, the road may be approximately selected.

(d) To determine the area of the drainage basin and the capacity of the reservoir.

(e) To visibility of the given point can be estimated.

2. In mining - (a) Any change in level, flat or inclined seams, the anticlines or synclinal structures, domes or basins, etc. can be asserted from a contour map, and direction of dip can be calculated.

(b) it is a line of the strike and the amount

(d) To mark the highest flood level line.

(e) To determine the gradient of the proposed haul and haulage road in an opencast and underground mine.

(f) It is used for the installation of a pump head from the contour map.

(g) To determine cover over coal seams from stratum contour and surface contour.

(h) Tracing of the outcrop of the seams

(I) To the analysis of geological disturbance.

Locating of contours-There are two methods for locating contours.

1. Direct Method 2. Indirect Method

1. Direct methods very slow and tedious, but it is more accurate and is utilized for a small area in countering. In this method, the level of the points on the ground is exactly marked by level instrument or total station, and the position of the points is marked by theodolite, compass, plane table, or total station. The position of the points plotted on the plan and contour drawn by joining them by dotted curve lines.

2. Indirect methods - In this method, the spot of the points are taken in a series of the line along the cross-section or on the corner of the square. The position of spot Height was taken by the use of the total station, D GPS, or tachometer. Then the position of points plotted in the plan contours are drawn by interpolation.