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Rebuilding Terrace Systems

Rebuilding Terrace Systems

by Craig T. Scheuerman, Civil Engineering Technician
Natural Resources Conservation Service
Hays, Kansas

Terrace rebuilding is a subject we hear a lot about, but lately some new questions have been raised.

Do I need to rebuild every terrace in the field or can I just rebuild every other one?

To decide about rebuilding you first need to know something about how a terrace system is designed. Terraces are designed to contain a 10-year rain without overtopping. This means they can hold the total runoff from a rain that would have a 10 percent chance of occurring in any one year for the drainage area above the terrace.

When terraces are rebuilt, every terrace in the system needs to be restored to original design height for the system to have adequate capacity and to work properly. If only every other terrace were rebuilt, the old terraces with their low capacity would overtop.

The overflow runs down the slope and is caught by the rebuilt terraces. Since these terraces are only designed to handle the runoff from the area above, the excessive runoff from the old terraces would cause the newly rebuilt terraces to overtop.

If terrace spacing is a problem, an entire new system may help. Spacing can be adjusted by installing new terraces with wider channels. In certain situations, a new system can improve alignment and farmability.

For more information about terraces, please contact your local Natural Resources Conservation Service (NRCS) office or conservation district office located at your local county USDA Service Center. To learn more about NRCS, visit the Kansas NRCS Web site at www.ks.nrcs.usda.gov.

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