What is Topography?
to·pog·ra·phy -
A detailed description or representation on a map of the natural and artificial physical features of an area.
Its a gorgeous morning and you are out hiking on your favorite trail. The terrain is steep and the ground uneven. You manage to tip toe across a stream without getting your boots wet. You make it to the top and peer over the hills and valleys you have just risen above. You made it.
So just how do those rivers and steep trails translate onto paper?
Topographic maps represent the three-dimensional landscape in two dimensions. We can find out the location of peaks, valleys, ridges among other land features. These maps can also show you whether you will be traveling uphill or downhill on a particular road or trail.
Contour Lines
Elevations on a topographical map are marked with contour lines, which connect points of equal elevation. Imagine walking around a mountain in a circle, never going uphill and never going downhill but staying at the same altitude. If you traced the path you walked, you would have a contour line on a map. Contour lines are typically separated by 40 vertical feet, though you should check the map you're using to be sure, and every fifth contour line is usually marked with an actual elevation.
Land Features
The shape of the contour lines can tell you the shape of the landforms in a particular area. For example, concentric circles show a peak, with the smallest circle marking the summit. Contour lines that are close together indicate that the land is very steep, while contour lines that are spread apart show that the land is relatively flat.
Soil
Every project is unique and so is the earth beneath it. Soil type, Ground conditions and stability are essential to determine whether the property is suitable for a particular type of building as well as the best place for the structure to go. Topography also has a large impact on just how the soil is formed. Where does all that rain go? It doesn't just stay up on that mountain top. How does that effect the soil below? All of these details make up the topographical picture of our homes and businesses.
Topography and Your Site Plan
Did you know that the U.S. Geological Survey began surveying land in 1879 in order to create these commercially accessible topographical maps? There are more than 54,000 in existence today. We at mysiteplan.com use the information from these maps to add contour lines in 2-5 foot intervals on your custom siteplan.
Notice the contour lines in this image? The lines that are closer together indicate a steeper elevation and the lines farther apart indicate a wider plain.
The next time you step onto the road less traveled, you may start to see those rolling hills, valleys and streams a bit differently and understand just how every elevation and even the soil might effect your next building project.
- Heidi Chandler
