How do you select contour interval?

How do you select contour interval?

Divide the difference in elevation between the index lines by the number of contour lines from one index line to the next. In the example above, the distance 200 is divided by the number of lines, 5. The contour interval is equal to 200 / 5 = 40, or 40-unit contour intervals.

How does accuracy affect the choice of contour interval?

Accuracy need of surveying work also decide the contour interval. But in case of location surveys where the desired accuracy is less, higher contour interval should be used. Time and Cost. If the contour interval is small, greater time and funds will be required in the field survey, in reduction and in plotting the map …

What is the purpose of the contour interval?

A contour line is a line drawn on a topographic map to indicate ground elevation or depression. A contour interval is the vertical distance or difference in elevation between contour lines.

What types of contour intervals are there?

There are 3 kinds of contour lines you’ll see on a map: intermediate, index, and supplementary.

• Index lines are the thickest contour lines and are usually labeled with a number at one point along the line.
• Intermediate lines are the thinner, more common, lines between the index lines.

What is a contour interval and on what factors does it depend?

The contour interval depends upon the general topography of the terrain. In flat ground, contours at small intervals are surveyed to depict the general slope of the ground whereas high hills can only be depicted with contours at larger contour interval.

What are the methods of contouring?

There are basically 2 methods of contouring – Direct Method and Indirect Method.

• Direct Method of Contouring : High degree of precision is required for large-scale maps with small contour interval.
• Indirect Method of Contouring : It is suitable for undulated ground and hilly areas.

What are contour barriers?

Contour barriers are contour strips which intercept downslope flowing water and soil particles. These barriers slow down the water movement and reduce its erosive force. They also filter out and trap many of the suspended soil particles, keeping them from being washed out of the field.

What are the factors on which contour lines are based?

The contour interval is inversely proportional to the scale of the map. If the scale is small, the contour interval should be large and vice versa. The general terrain of the area determines the contour interval. For a flat area, the contour interval should be small.

What is a disadvantage of using a smaller contour interval?

Disadvantages of using contour to represent relief on the map. Contour fail to show some of the heights due to limitation of vertical interval.

What are the characteristics of Contour?

Characteristics of Contours

• Must close on themselves, on or off the map.
• Perpendicular to the direction of max.
• Slope between them is assumed uniform.
• The distance between them indicates the steepness of the slope, gentle or steep.
• Irregular signify rough, smooth signify gradual slopes.

What is contour gradient?

Explanation: Contour gradient is a line lying throughout on the surface of the ground and preserving a constant inclination to the horizontal. If the inclination of contour gradient is given, its direction from a point may be easily located either on the map or on the ground.

What is contouring and its characteristics?

Contours show distinct characteristic features of the terrain as follows: i) All points on a contour line are of the same elevation. ii) No two contour lines can meet or cross each other except in the rare case of an overhanging vertical cliff or wall. iii) Closely spaced contour lines indicate steep slope.