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CHAPTER 8 : Contouring (Characteristics (All points in a contour line have…
CHAPTER 8 : Contouring
Introduction
- Imaginary lines that connect points of equal elevation/height/altitude
- Obtain by joining points of equal elevation on the map
- Found in contour maps and topographic maps
Types of line
Index contour
- every 5th contour line is printed darker or thicker
- elevation printed on it
- every 50m, 100m elevation interval
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Contour interval
- four intermediate contour lines fall between the index contour
- no printed elevation on it
- equal spacing
- 10m, 20m interval
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Characteristics
- All points in a contour line have the same elevation.
- A uniform slope is indicated when the contour lines are uniformly spaced
- A plane surface when they are straight, parallel and equally spaced
- Flat ground & gentle slope is indicated where the contours are widely separated
- Steep slope (cerun curam) is where the contours lines run close together
- A series of closed contour lines on the map represent a hill, if the higher values are inside
- A series of closed contour lines on the map indicate a depression if the higher values are outside.
- If the higher values are inside the bend or loop in the contour, it indicates a ridge (rabung)
- If the higher values are outside the bend, it represents a valley
- Cannot merge or cross one another on map except in case of an overhanging cliff
- Never run into one another except in the case of vertical cliff.
- Depressions between summits is called a saddle. It is represented by four sets of contours as shown. It represents a dip in a ridge.
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