Recently at Milkwood Farm, Craig Sponholtz led a course in Applied Watershed Restoration, and taught us all a bit about how to tackle on-farm erosion control with human-scale solutions.
One of the things we constructed as part of the workshop was a media luna, a simple but effective rockwork structure that can be used to subtly manipulate sheet flow in a number of ways to prevent erosion…
This media luna was constructed at the toe of an eroded gully we selected for this workshop, which had other rockwork erosion control features installed above it.
The media luna itself is actually a double-ended one (so to speak) and in the shape of a subtle ‘S’ – one end of it is dispersing sheet flow, the other end concentrating sheet flow, as the situation requires…
The effect of this rockwork feature should hopefully result in the water running down this gully becoming subtly managed to become less erosive as the water slows down. Slow water means a more active seed bank in the soil below, so in time more grasses and sedges should pop up to hold the fragile soils together.
This rockwork was made like a jigsaw puzzle, one rock placed at a time. The result is a wider interlocking band of rubble, one rock high, in a slight but carefully surveyed concave (or convex) arc. It looks so simple. And it is (in some ways), once you get the hang of it.
The implications for the landscape down slope from this media luna, however, are joyfully complex. With the water slowed and directed towards being non-erosive, we should see some good improvement in this gully, with little extra intervention.
Big thanks to Craig Sponholtz of Dryland Solutions, to the Central West CMA and to our comrades at RegenAG for making this workshop possible. Thanks also to all the workshop participants and crew who made the whole thing flow.