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Title
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Contour Trenches_Design Manual
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Description
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Contour trenches are ditches dug along a hillside to follow a contour and run perpendicular to water flow. The soil excavated from the ditch is used to form a berm on the downhill edge of the ditch, which is planted with permanent vegetation to stabilize the soil and trap sediment. The purpose of contour trench construction is to reduce surface water flow velocity, promote infiltration, and prevent pollutants from draining into water bodies. To construct a properly functioning contour trench, it is important to accurately follow the hill's contour. A low-cost method to determine the contour is to build an A-frame level, which is marked with stakes for excavation. Contour lines are imaginary lines across a slope that are the same height at all places along the slope. To measure contour lines, an A-frame level can be made at no cost and used by one farmer. In areas with heavy storms, it may be dangerous to prevent water completely from flowing down a slope.
