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What is a Topographic Survey?

B. Turner
B. Turner

A topographic survey is an engineering process used to map the surface of the earth. Topographic assessments differ from other types of surveys in that they are primarily concerned with mapping the shape of the earth, including land contours and elevations, rather than roads. Upon completion of a topographic survey, mapmakers can create a topographic, or contour map. These maps are then used for land planning, construction, mining, and agriculture. Hikers and campers may also rely on a topographic survey map when exploring trails or wilderness areas.

When completing a survey, engineers map the location of both natural and man-made structures within a defined area. This includes bodies of water, land contours, and even buildings or fences. The survey measures the distance between these elements, as well as changes in elevation between each one. A topographic survey generally won't show roads or very small man-made fixtures.

Topographic surveyors might use traditional measuring devices to do their work.
Topographic surveyors might use traditional measuring devices to do their work.

The surveying process begins as topographic surveyors divide an area of land into a grid pattern. Flags or other markers are used to create grid lines, which help surveyors stay organized throughout the process. Engineers may use traditional measuring devices or even satellites and aircraft to measure distance between different points within the grid. These professionals then rely on specialty surveying equipment to measure and calculate elevation changes and angles between each point.

A topographical surveyor is a professional who specializes in establishing the location of physical features and dimensions on the Earth.
A topographical surveyor is a professional who specializes in establishing the location of physical features and dimensions on the Earth.

Upon completion of the topographic survey, engineers create a topographical map, which uses contour lines to represent the shape of the earth. When lines are placed close together, this indicates a relatively steep area of land. Lines that are further apart represent shallow or moderate elevation changes. The lines are typically labeled to show the elevation, measured in feet or meters above sea level. To keep the map from appearing too complex, contour lines may be labeled intermittently.

Hikers often make use of topographical survey maps when exploring trails.
Hikers often make use of topographical survey maps when exploring trails.

Every fourth or fifth contour line may be darkened to help readers distinguish between different sets of lines. These darker contours are known as guide lines, and are labeled with the land elevation at that point. V-shaped areas within the lines represent streams or rivers, while concentric circles represent hills or mountains. These circles may also represent a pit or void in the earth, so users must read the related elevation information to avoid potential mistakes. The smallest circle within a group of larger circles typically represents the highest or lowest point within the surrounding area, while larger circles show slopes around this apex.

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    • Topographic surveyors might use traditional measuring devices to do their work.
      By: CandyBox Images
      Topographic surveyors might use traditional measuring devices to do their work.
    • A topographical surveyor is a professional who specializes in establishing the location of physical features and dimensions on the Earth.
      By: CandyBox Images
      A topographical surveyor is a professional who specializes in establishing the location of physical features and dimensions on the Earth.
    • Hikers often make use of topographical survey maps when exploring trails.
      By: blas
      Hikers often make use of topographical survey maps when exploring trails.
    • Topographic surveys are primarily concerned with land elevation, rather than roads.
      By: kez53
      Topographic surveys are primarily concerned with land elevation, rather than roads.
    • A inclinometer may be used to determine the slope of an incline or decline during a topographic survey.
      By: Petro Teslenko
      A inclinometer may be used to determine the slope of an incline or decline during a topographic survey.