When constructing a check dam, the center should be how much lower than the outer edges?

The correct answer is six inches because a check dam is designed to slow down water flow in channels, allowing sediment to settle and preventing erosion. The design principle of having the center of the check dam lower than the outer edges creates a slight dip that facilitates water pooling behind the dam. This pooling effect increases the opportunity for sediment to settle as the flow velocity decreases when the water backs up slightly. A height difference of six inches is typically sufficient to achieve this equilibrium, striking the right balance between functionality and stability. This specification is derived from best management practices in erosion control, ensuring effective sediment capture while maintaining the structural integrity of the dam.