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Best Management Practices (BMPs) can prevent or minimize the impact of forestry activities on rivers, lakes, streams, groundwater, wetlands, and visual quality.
There are a variety of measurement tools that can assess a woodland. The tools can be sophisticated equipment items purchased from vendors or they can be homemade devices. This fact sheet will describe how to make and use a homemade tool for determining slope.
Slope is the change in elevation between two points. It is expressed as a percent change in elevation per unit of distance traveled. Loggers and foresters need to determine slope when constructing roads and determining the spacing of water bars and broad-based dips. Water bars and broad-based dips help prevent erosion and keep sediment from reaching water.
You can determine slope using a measurement tool made with two wooden dowels or stakes, string, a felt marker or tape, a line level, and a ruler. While the dowels or stakes do not need to be the same length, they may be easier to use if their length is equal. To make the tool:
To measure the slope:
% slope = (change in elevation/horizontal distance) x 100
As an example, assume the dowels are 100 inches apart and the string had to be moved 10 inches to make it level. The slope is then calculated as:
% slope = (10 inches/100 inches) x 100 = 10% slope
Once you determine slope, you can determine the spacing between water bars and broad-based dips by referring to the appropriate table(s) in your state’s water quality BMP manual.
Homemade tools for calculating slope are less expensive than commercially available tools. They provide accurate enough estimates of slope to determine the spacing of water bars and broad-based dips.
Homemade tools are less accurate than commercially available tools. They may be more difficult to use, too. Also, they are limited to measuring slope, whereas commercially available tools may have additional capabilities.
For more information about the spacing of water bars and broad-based dips, see your state’s water quality BMP manual.
University of Minnesota Extension Service, Minnesota Department of Natural Resources, Minnesota Logger Education Program, Michigan Department of Natural Resources, Michigan State University Extension, and Wisconsin Department of Natural Resources.
In accordance with the Americans with Disabilities Act, this material is available in alternative formats upon request. Please contact your University of Minnesota Extension office or the Extension Store at (800) 876-8636.