In the demo above, every point in the graph has an x and y value. Contour lines aren't just limited to giving us info about mountains though, they can help us visualise a surface described by a mathematical function. These are known as contour lines, and every point on the line is at the same height. Line 1 starts with the contour interval, not the projection point.If you've ever looked at a map, particularly of a hilly or mountainous region, you may have noticed groups of lines like this: Slope Worksheet - Use the information from the example above and complete the slope worksheet. 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. A contour line is a line drawn on a topographic map to indicate ground elevation or depression.
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