Swales on less than 4° slope

Hello all,

Recently purchased a large piece of land (160 acres) that over time we hope to restore, build soils, soak and store the little rain water and run off we receive per year (Average 7in annually)

The land in red surrounding the house is irrigated with sprinklers. The area in green is actually sub irrigated by underground water canals (this area is geothermal). It never needs water, even in the summer. I want to add swales to both these areas to help slow the water we have coming in and increase water storage as well as start my food forest on the red areas around the yard by continuing the expand on the trees we already have around the house. on contour is where I had planned each swale.

In the more densely sage brush wilderness areas the soil shows signs of clear erosion and run off.

Just looking for a little insight on swale depth and width, or maybe even an alternative for the desert climate!

Cheers,
Jesse

Coupla points to consider;
- that erosion will need to be stopped, it always gets worse. Control is both simple and hard, you need to slow the water speed down so it no longer erodes.
  Small stone walls, special grass, I have just forgotten its name. management of roadways and culverts.
- swales may cause problems with underground water action, ask around or observe things.
- Irrigating in the desert can cause salting if the area is susceptible to salting.

As for water storage, I think open dams would be wasteful, large and pricey tanks are really the only way to keep it.
I use 250,000L tanks costing in Australia $Au 18,000.

With 7 inch rainfall a lot of roofing would be needed to catch that.
Look at the link in my signature, its discussed there.
All the best.