Understanding Contours
What are Contour Lines
•Contours Lines - are imaginary lines that joinpoints of the same height above the datum(points of equal elevation)
What are Contour Lines
RL 10.000 AHD
What is the datum ?
What are Contour Lines
RL 20.000 AHD
What is the datum ?
What are Contour Lines
RL 30.000 AHD
What is the datum ?
What are Contour Lines
RL 40.000 AHD
What is the datum ?
Contour Interval
•The contour lines represent the height of theland in the form of a Reduced Level above thedatum.
• Each contour will represent a Reduced Level,so an impression of the shape of the land canbe formed the contours must be determinedat a regular interval.
•This is the Contour Interval.
Contour Interval
In this case thecontours are at aregular interval of 10mof vertical elevation
Contour Interval
Each Terrace represents adifferent Reduced Level
The difference in Verticalheight is the contour interval
Gentle Slope
Plan View
Depressions
Top of Hill
Using Contours
RL 47.400
RL 47.200
RL 47.000
RL 46.800
RL 46.600
Lets us quicklydraw a profileof the land
ContourInterval
Must be
regular
RL 47.400
RL 47.200
RL 47.000
RL 46.800
RL 46.600
The Closer the
Contour line toeach other thesteeper theland
RL 46.400
RL 46.200
RL 46.000
RL 45.800
RL 45.600
Horizontal Distances will be irregular