Saturday, August 15, 2015

More about washes

Mammatus clouds forming over the Mojave Desert
We've lived in the Mojave Desert going on two years now and have spent the time observing the natural processes around us. This involved a lot of sitting on the porch, and often beer. Now that we've been through two large rain events, here's what we've pieced together regarding washes.

Washes run to the roads.
All washes run to the roads. Most roads have been overgraded and so are lower than the roads. The only place I've seen roads at the same level as the desert is far out in Wonder Valley. Because of this the roads become flood channels. Instead of staying on the desert, water is diverted to flood channels and, I guess, eventually the ocean.

The water coursing in the middle is our driveway and the water is congregating there and running to the street.
Washes go wherever the hell they want to go.
You can doctor your washes: adding swales, one-rock dams, gabions, zuni ponds, whatever, but when that heavy rain comes, it's going to laugh at you. A flash flood may take a previous route, or cut a brand new route. It will wreak havoc with your permaculture designs.

Water pooling before it begins traveling in a wash.
To divert water away from this porch you might put a berm where the split rail fence is.
Rain and washes mound the plants.
As water cuts through the desert it cuts away the sand around plants, leaving the root ball and the sand it holds. Over time, more sand blows up against this and the plant looks like it grows on a mound.

Mounding has many causes: erosion from water and wind, sand drifting around plants, and displacement of earth under the plant from animals digging shelters.

The plant in the middle of the picture has had the sand washed away around its roots.
When this wash begins to flatten out, due to more wind and rain, the plant will remain on a mound.
Washes can be diverted, to a degree.
Rocks and berms will divert flooding to a degree, but it may be just the degree you need. Determine which direction the water comes to your cabin and gently angle the water away with a row of the biggest rocks you can find. Or you can rent a backhoe and build the biggest berm you can across from your cabin. This will not last forever as water laughs at sand.

We cut a swale to the left of this wash. The last storm filled it with sand, making it disappear entirely.
Washes are called washes because they wash stuff away. This seems obvious, right? I see plants on the sides of washes and plants IN washes. You can plant in washes but you might lose your plants. We did not lose the plants we planted in the washes, but they were hanging on for dear life and most lost their cages which is an easy fix. We'll see if they do any better for the placement.

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