Question: How Do You Read A Contour Survey?

What is a index line?

A contour line accentuated by a heavier line weight to distinguish it from intermediate contour lines.

Index contours are usually shown as every fifth contour with their assigned values, to facilitate reading elevations..

How many methods of contouring are present?

2 methodsHow many methods of contouring are present? Explanation: There are 2 methods of contouring: direct and indirect. In direct method, the points of elevation are located physically and then plotted on the map. Indirect method uses contouring with the help of grids.

What is the space between contour lines called?

Contour lines–usually curved, parallel brown lines–show the shape and elevation of the land by connecting points of equal elevation. … The space between the contour lines is called the contour interval and represents a specific (set) distance.

Why do contour lines never cross?

Contour lines can never cross one another. Each line represents a separate elevation, and you can’t have two different elevations at the same point.

What is meant by contour interval?

A contour interval is the vertical distance or difference in elevation between contour lines. Index contours are bold or thicker lines that appear at every fifth contour line. If the numbers associated with specific contour lines are increasing, the elevation of the terrain is also increasing.

How do you read contour lines on a site plan?

Closely spaced contour lines indicate steep slope. Widely spaced contour lines indicate gentle slope. Equally spaced contour lines indicate uniform slope. Closed contour lines with higher elevation towards the centre indicate hills.

What does it mean when contour lines are far apart?

Contour lines that are relatively close together indicate a slope that is fairly steep. Contour lines that are further apart indicates a slope that is relatively flat.

What is a depression contour line?

A closed contour, inside of which the ground or geologic structure is at a lower elevation than that outside, and distinguished on a map from other contour lines by hachures marked on the downslope or downdip side.

What are contours measured in?

A contour is a line drawn on a map that joins points of equal height above sea level. For 1:25 000 scale maps the interval between contours is usually 5 metres, although in mountainous regions it may be 10 metres.

What is the shape of contour lines in case of a valley?

What is the shape of contour lines in case of a valley? Explanation: Contour lines cross a valley line at right angles. They form sharp curves of V shape across it with the convex side of the curve towards the higher ground.

What are the 5 Rules of contour lines?

Rule 1 – every point of a contour line has the same elevation. Rule 2 – contour lines separate uphill from downhill. Rule 3 – contour lines do not touch or cross each other except at a cliff. Rule 4 – every 5th contour line is darker in color.

What are 3 types of contour lines?

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.More items…

What are the basic features of contour lines?

Other characteristics of contour lines are: – Horizontal distance between contour lines is inversely proportional to slope. – Uniform slopes have uniformly spaced lines. – Along plane surfaces, contour lines are straight and parallel. – Contour lines are perpendicular to lines of steepest slopes.

Why do we use contour lines?

The purpose of contour lines is to represent the tridimensional shape of the terrestrial surface on a bidimensional map. Contour lines are the intersection of an horizontal plane parallel to the reference level and the topographical surface to describe. Consequently: Contour lines are always closed curves.

What do you mean by contour lines?

Contour line, a line on a map representing an imaginary line on the land surface, all points of which are at the same elevation above a datum plane, usually mean sea level. map: contour lines. The diagram illustrates how contour lines show relief by joining points of equal elevation.

How do contour lines work?

Contour lines are lines drawn on a map connecting points of equal elevation, meaning if you physically followed a contour line, elevation would remain constant. Contour lines show elevation and the shape of the terrain. … In order to keep things simple, topographic maps show lines for certain elevations only.

How do you calculate contours?

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.