Contour buffer strips are strips of prairie grass or other perennial vegetation placed along topographic contours. They are used to intercept overland flow and prevent sediment from running off into natural waterways. They can be placed at specific spacing along the slope or at the foot slope.

Contour Buffer Strip example

The concept is similar to terracing, although slope steepness is usually the reason for distinguishing between contour buffers or terraces where terraces are commonly used in steeper-sloped areas.

Practice Spacing

NRCS has suggested certain spacing for contour buffer strips and terraces within a field. The tool uses these recommendations for siting contour buffer strips and for the appropriate spacing of them within the ACPF.

By finding the 3rd quartile slope within each field, we determine which possible contour intervals will be applied to that field.

There are three steps to the process. The contour interval selected will result in a spacing approximately equal to the NRCS recommendation.

The tool begins to place contour buffer strips by first masking out 4%–15% slopes by field within row-crop agricultural land, this does not include pasture. The mask is smoothed by majority filter so that holes within the mask are filled.
Contours are then generated within each field using the defined contour interval that was based on the slope of that field.
Concentrated flow paths greater than 2 acres in drainage area are buffered by 10 meters and are removed from the contour buffer strip output. Contour buffer strips are not intended to intercept concentrated flow paths.

Note: Only contours greater than 100 meters in length are maintained and then added to the output. This output is then buffered to a user-specified width, which as a default is set to 15 feet.