BeginnerTopic 23 of 112Civil & Structural
Contours and maps
Lines of equal elevation represent terrain.
In depth
Contour lines join points of equal elevation; closely spaced contours indicate steep slopes. Contour interval choice depends on scale and terrain. Maps include scale, grid, legends. Digital terrain models and GIS support volume, cut-fill and watershed analysis.
Key points
- Contours never cross except at cliffs
- V shapes point upstream
- Spot heights
ExampleEarthwork volumes between design and original surfaces are computed from contour data.
Contours show the shape of the ground on a map, so they are the basis for grading, drainage and route planning.
What is Contours and maps?
Lines of equal elevation represent terrain.
Why is it important to understand contours and maps?
Contours show the shape of the ground on a map, so they are the basis for grading, drainage and route planning.
What does a contour line show?
A line joining points of equal elevation, and closely spaced contours indicate steep ground.
How do you read a steep slope from a contour map?
Close spacing of contour lines means a steep slope, while wide spacing means gentle ground.
How is Contours and maps used in practice?
Typical applications include choosing a route for a road that avoids steep slopes, planning the drainage direction across a building plot and estimating the volume of earth to be moved for a platform.
What should I learn before Contours and maps?
Study "GPS and GNSS surveying" first (topic 22 of 112 in Civil & Structural). It covers the groundwork this topic builds on.
What are the key points of Contours and maps?
Contours never cross except at cliffs. V shapes point upstream. Spot heights.
Can you give an example of Contours and maps?
Earthwork volumes between design and original surfaces are computed from contour data.
What comes after Contours and maps?
The next topic is "Site investigation", which builds directly on this one.
How difficult is Contours and maps?
It is classed as Beginner in Civil & Structural (topic 23 of 112). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.