## Contour and Contour Interval
Definition (1 mark)
A contour is an imaginary line joining points of equal elevation (reduced level) on the ground surface.
Factors Affecting Contour Interval (2.5–3 marks)
Contour interval is the vertical distance between two consecutive contour lines. It depends on the following factors:
1. Nature of Terrain
- Flat ground → small contour interval
- Steep ground → large contour interval
2. Scale of Map
- Large scale map → small contour interval (more detail)
- Small scale map → large contour interval
3. Purpose of Survey
- For detailed engineering work → small contour interval
- For general mapping → larger contour interval
4. Accuracy Required
- Higher accuracy → smaller contour interval
- Less accuracy → larger contour interval
5. Time and Cost
- Small contour interval → more time and cost
- Large contour interval → less time and cost
Key Concept
- The contour interval is kept constant throughout a map to maintain uniformity and clarity.
Conclusion (1 mark)
Contours represent equal elevations, and the selection of contour interval depends on terrain, scale, purpose, accuracy, and cost, ensuring proper representation of ground features.
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