What is the maximum spacing allowed between check dams when the top of the upstream dam is at the same elevation as the top of the downstream dam?

The maximum spacing allowed between check dams when the tops of the upstream and downstream dams are at the same elevation is determined by the need to effectively slow down water flow and capture sediment. When both dams are at the same height, the check dams function to control the runoff and sedimentation, but they are less efficient in terms of elevation change to create a significant drop for sediment trapping.

Therefore, setting the maximum spacing based on the bottom level ensures that water does not flow too freely, maintaining adequate control over sediment movement. This spacing allows for a more controlled flow path, preventing erosion and the potential for sediment to be carried away unchecked.

In practice, the spacing guideline is primarily concerned with maintaining effective sediment control while accounting for the hydraulic conditions set by the dam height. Thus, establishing the maximum spacing at the bottom level is essential for optimizing the performance of the check dams in sedimentation control scenarios.