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Steps in Constructing a Contour Map Using the Analytical Method

There are various types of contour maps and their basic function is to visually depict a gradient. A gradient is a shift or change in values, such as a change in temperature or elevation. Commonly, contour maps are used to show weather and temperature changes on news broadcasts or as topographic maps, showing the change in elevation over a given area of land. The same steps can be applied to any type of contour map.

Things You'll Need

List of data points or field area for measurement
Drawing (mapping) supplies

Instructions

- 1
  
  Contour maps can cover any scale of data area.
  
  Designate a field area for collection of data points. The field area of study can be any scale ̵2; as small as your back yard or as large as the the whole world. Once the data points are collected, analyze the data and determine the highest and lowest points. After identifying these points, calculate the total difference between them. This number will be used to determine your contour interval.
- 2
  
  The contour interval on this map is 20, because there are 5 contour lines between 400 and 500.
  
  Calculate the contour interval based on the difference between the highest and lowest measured data points. The contour interval determines how detailed the map is. For instance, if the difference between the highest and lowest points is a large number, such as 1,000, a small interval between contour lines, such as 10 or 20, would make the map too detailed. A contour interval of 50 or 100 would be more sensible. Decide how detailed the map should be and choose a contour interval. For example, if the difference is 1,000 and there should be 10 contour lines, 1,000/10 = 100; therefore, the contour interval should be 100 or vice versa, If the difference is 1,000, and the decision is to create a contour interval of 100, there will be 10 contour lines.
- 3
  
  This topographic map shows circular contours that represent mountains or basins.
  
  Connect equal values that are located in proximity to one another. Data points of the same values should be connected together with the contour lines. If the contour lines fall in between two data points, extrapolate the line relative to the data point to determine its position. For instance, if the contour interval is 100 and the data point is 125, the 100-value contour line will fall closer to the point than the 200-value line.
- 4
  
  Contour lines are 2D visual depiction of a 3D area.
  
  Evaluate the patterns to determine whether the contour lines are correct. Different types of contour maps display different types of patterns. A contour map of temperature may show a front of other meteorological phenomenon. Contour maps depict elevations of mountains and depressions as irregular circles that follow the pattern of the land. Consider if the patterns and shapes of the contours accurately describe the data.

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