My 70 acre property is in a sand/sandy loam/glacial rock region (the rocks are almost all smaller than your fist). I have a ravine running east/west through my property terminating in a 6 acre pond, and on the south side of this ravine (north facing slope), I have several deeply eroded gullies, each with 4-10 acres of drainage feeding it. The property has ~70' elevation drop over 3,000' running west to east. The ground is typically sand/sandy/loam small rocks for 1-4' then red clay below it. It was a 90% loblolly pine forest with some oaks/eastern cedars/hickory scattered in it until about 1.5 years ago when a drought+forest fire (Bastrop Complex Fire) destroyed 95% of all the trees. I heavily seeded it with cover crops which have held most of the soil in place since then. Other parts of my property lack the small rocks and I already have 3,200' of hugelkultur/swales in place there.
I want to start doing water retention projects on this north facing slope and am considering doing a lot of smaller 20-50' swale structures which cascade into each other in the drainage areas.
My question though is concerning the gullies. They range from 150 to 250' in length, with widths starting at 5' ranging up to 70' (at the top) at the outflow to the ravine. Their depths are 20-30' at the ravine from the bank above, with very steep slopes of 45-60 degrees. Today they are shady microclimates, and you see mostly mosses and ferns growing in them.
My thought has been to make multiple dams within the gullies to slow the water down and let it soak in and percolate out over time. The primary challenge I see is that the terrain is not great for equipment given these slopes, and manually doing this is quite daunting! I can see how it might be done with heavy equipment by building equipment travel ways in/out of the ravine at every dam to be built, but I'm hoping to avoid that amount of soil disturbance.
Perhaps Sepp or someone else here has experience with this particular problem and can share their experiences?
Build alot of ponds to stop the waters that are feeding the gullies.
At the start of the gullies where they are small build dams out of log/trees and stones.
You can also build gabion dam. mesh filled with rocks.
Howdy Gordon, I have a gully on my property that is about 20 ft deep and I have been slowly throwing rocks and logs down in there at a point where it narrows. Each year the soil, that erodes with the spring thaw , has been settling out. I hope to build up a dam, maybe 10 ft or so, and have a relatively flat area upsstream of it, to at least slow the erosion some.
This question is quite impossible to give a sure answer to without seeing the property for yourself. You have to see the plants that are growing, where on the landscape the area of concern is, and the land forms.
With big erosion gullies and canyons the problem is usually above the gully, and this is where the problem needs to be addressed. Restoring the hydro-logical balance helps mitigate this kind of erosion. It is important for the surface of the earth to be in shade, so that when moisture comes it is able to absorb it. If the ground is warmer than the falling rain it will reject the water. This causes the water to run down hill causing erosion and flooding. Then because the water has not been stored there are concerns about drought and fire later in the year.
The best example of this is to go outside and experiment with it for yourself. Leave some soil exposed to bake in the sun and some covered by leaf mulch and observe the difference. Pour water on each and see how much the different soils absorb. Experience is the best teacher, from observing nature we can learn everything we need to know. A greater level of understanding is reached when you experience something, far greater than any periodical or video.
For those that tend to be more couch inclined here are some videos that illustrate the point.