Characteristics of contours

CHARACTERISTICS OF CONTOURS

1. All points in a contour line have the same elevation.

2. Contour lines are closed curves.

3. The spacing between contour lines depends upon the slope of the ground. In steep slopes, the spacing is small and for gentle slope, the spacing is large.

4. When contour lines are uniformly spaced, it indicates the uniform slope of the ground.

5. When contour lines are straight and parallel with equal spacing, it indicates plane surface.

6. Irregular contours denote uneven slopes, whereas smooth contours denote gradual slope.

7. The series of closed contours with increase in elevation from inside to outside in plan denotes a Depression. See Fig. 51.

8. A series of closed contours with increase in elevation from outside to inside in plan denotes a Hill. [Fig. 52.]

9. Contour lines cross a Valley line at right angles. The contour lines form V-shaped curves with their convexity towards the higher elevation, i.e., contours of lower elevations are inside the bend. The same contour appears

USES OF CONTOUR MAPS

1. Used to find the topography of the country.

2. Used to compute the quantities of earth work for any work.

3. Used to determine the catchment area of a river, lake or a reservoir.

4. Used to compute the storage capacity of reservoirs.

5. Used to select the most suitable projects such as a highway road, railway or canal, etc.

6. Used to trace out the drainage areas of a stream or a river.