![]() ![]() The run is 1000 feet and the rise in elevation is 120 feet. Step 4. Use the slope percent equation and solve. Set up the cancellation table so all units will cancel, except the desired unit, feet. Step 2. Use the appropriate conversion factor to convert the horizontal map distance to horizontal ground distance. The horizontal map distance measures 0.5 inches. Step 1. Measure the horizontal map distance between points A and B to get the vertical ground distance. The horizontal distance between points A and B can be measured with a scaled ruler and used to determine the slope percent.Įxample 4 - What is the slope percent in Exercise 2 above?įor this computation, the rise, or vertical ground distance, and run, or horizontal ground distance, are needed. Notice the tick marks pointing toward lower elevation. The figure above illustrates a depression and its representation using contour lines. (b) Notice how a mountain saddle, a ridge, a stream, a steep area, and a flat area are shown with contour lines. The figure above illustrates various topographic features. Contour lines that are very close together indicate a steep slope. Widely separated contour lines indicate a gentle slope. The peak is normally considered to be located at half the interval distance. ![]() Note: The intervals are increasing, therefore, the contours indicate a hill. From the contour map, a profile can be drawn of the terrain.Įxample 2 - Draw a profile showing the elevations of the contours. The even spacing indicates the hill has a uniform slope. The contour lines in this figure are equally spaced. Pick two contour lines that are next to each other and find the difference in associated numbers. Sharp contour points indicate pointed ridges.Įxample 1 - In the graphic below, what is the vertical distance between the contour lines? Contour lines tend to enclose the smallest areas on ridge tops, which are often narrow or very limited in spatial extent. A rounded contour indicates a flatter or wider drainage or spur. They then cross the stream and turn back along the opposite bank of the stream forming a "v". As a contour approaches a stream, canyon, or drainage area, the contour lines turn upstream. If the numbers associated with the contour lines are decreasing, there is a decrease in elevation. If the numbers associated with specific contour lines are increasing, the elevation of the terrain is also increasing. Index contours are bold or thicker lines that appear at every fifth contour line. A contour interval is the vertical distance or difference in elevation between contour lines. Some industries that use topographic maps extensively are: engineering, exploration, construction, natural resource management, recreation, and public works.A contour line is a line drawn on a topographic map to indicate ground elevation or depression. If the contours have wide spaces in between - or aren’t there at all - then the terrain is relatively flat. If the contours are placed close together, then you’re looking at a steep slope. To determine the gradient of elevations, observe the amount of space in between the lines. Elevations are marked on the index contour lines only. The index contours are a darker or wider line in comparison to the regular contour lines. The index contour lines are the only ones labeled. To make topographic maps easier to read, every fifth contour line is an index contour. This spacing is called the contour interval. Topographic maps show contour lines for only certain elevations. Many of you who hike outside are familiar with this type of map. Topographic MapsĪ contour map is another name for a topographic map, illustrated from contour lines.Ī topographic map is a two-dimensional representation of a portion of the three-dimensional surface of the earth. Contour lines show both the elevation and illustrate the shape of the terrain. Some of the contour maps look like outlines of animals such as fish, or butterflies.Ĭontour lines are lines drawn on a map connecting points of equal elevation. Every contour map is unique! Some are jagged, others are almost perfectly symmetrical. We enjoy viewing the black and white contour lines that are generated from each pile measured just as much as the color images. It is wonderful to view sunny stockpile images with blue skies, especially when the weather is dreary here in the Pacific Northwest. Our team views color images from stockpiles that have been measured from exotic locations such as Australia, India, South America, Chile, New Zealand and more. Stockpile Reports has customers located all over the world. Our stockpile reports also feature a black and white topographical map of the pile, rendered using contour lines. Fascinating Contour Lines and How They WorkĪuthor: Stockpile Reports Every stockpile measured by our customers generates a Stockpile Report with the stockpile’s photo and measurement video. ![]()
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