This also made me think of a neighbor farmer that has a couple fields that are parallel terraced.
Parallel terraces can be used in fields that the slope is such that the terraces "almost" run in a parallel. The advantage of farming parallel is that all farming practices can be farmed with the terraces (like contour farming) without the hassle of point rows like contour farming. By not farming across terraces they last a lot longer....... but I digress.
The reason they are important to this discussion is that rarely do parallel terraces end up draining perfectly to the end of the field. To rectify this, pipes are buried in strategic locations to carry the low point of one terrace to the next down slope terrace. These are essentially underground culverts that have risers (and trash shields similar to trash risers built for pond overflow pipes) that the water drains out of the bottom of the terrace and discharge to where ever the water is desired to go.
A person could do this with a terrace going into a pond. It might not drain all the water in a big rain event, but a riser in the bottom of a terrace that could be capped (or slide gate) then under ground drainage to take the water down hill to an exit point. You can do a search for parallel field terraces for some pictures of the risers and construction.
