| Subject: |
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Web Soil Survey misuse |
| Name: |
|
David Harper |
| Date Posted: |
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Feb 22, 07 - 12:02 PM |
| Email: |
|
john.harper |
| Website: |
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http://www.vapss.org |
| Message: |
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The Web Soil Survey (WSS) is GREAT! Everyone I have spoken with has truly enjoyed using it. HOWEVER, the use of the data has been unknowingly abused by some.
USDA soil maps in Virginia were made at three main scales 1:24,000..1:15,840.. and 1:12,000. The WSS allows the user to zoom in to a larger scale which infers a higher level of accuracy than the original mapping scale intended. If the original mapper could of "zoomed in" he/she could draw in more delineations of similar or contrasting soils.
Then there is the line size issue. At 1:24,000 scale the line is approximately 100' wide on the true ground. Yet when a user zooms in to lets say 1:6,000, the line width remains the same on the map, yet may only be 40' wide on the ground.
The larger scale does not mean more accurate than the orginal scale the map was intended to be used.
If one wants to know what scale the map was originally created at, the second page of the PDF of the soils map displays the original scale it was made at.
There are many who know how to use this information properly; however, there are many that unintentionally use this information as fact at scales which were not meant to be used at. |
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