Types of Terraces

Bench Terraces

Bench terraces reduce land slope and allow run off from the upper side of the terrace to go into a lower portion where it spreads out and infiltrates. This BMP is most often brought to mind when the word terrace is used, and is employed most often in various mountain regions around the world.

Contour Terraces

Contour terraces have point rows and grassed waterway outlets that follow the lay of the land.

Parallel Terraces

These BMPs are so named because they are constructed parallel to each other, and where possible, in the direction of field operations. Parallel terraces eliminate the production losses associated with point rows and minimize the interference to farming operations when spaced at multiple widths of planting and harvesting equipment. A more specialized form of the parallel terrace includes the parallel tile outlet terrace.

Parallel Tile Outlet Terrace

Terraces that are constructed in parallel and discharge runoff through subsurface drains are known as parallel tile outlet terraces. With PTO terraces, water that is stored behind a terraced ridge is discharged through a surface inlet into a subsurface drain. The surface inlet, which is called a riser, has a restricted section to control the discharge rate, causing some of the runoff to be temporarily stored. This storage period is long enough for the sediment to settle out of the water, but not so long as to damage the crops.

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