Contour line
It
is an imaginary line which passes through points having same elevation or same
RL (reduced level). It is also called contour.
For
example:- A contour map of 90m indicate that all the points on that contour
line have an elevation of 90cm. Similarly, a contour line of 80cm indicates
that all points on that line are at an elevation of 80cm.
This
figure is the map of ground surface (like hill) which gives the elevation or
reduced level (RL) of different points on that particular ground surface.
Contour interval
It is the vertical distance between any two consecutive
contour intervals. The contour interval of the figure given above is 10 m.
What we did -
We
just subtracted the RL of contour having lower value (80m) from the RL of
contour having higher value (90cm).
Note:-There
is always a constant contour interval for a map or plan.
Horizontal equivalent:-
The horizontal distance between any two consecutive contour
lines is called horizontal equivalent.
The horizontal equivalent varies from point to point for a
ground. It depends upon the nature of the ground.
