Gabion = Rocks. Lots of them. In the course of the four days it took to build the gabion, I hauled approximately 6-tons of rock from a nearby mountain. Lots of fun :)
I then began to construct the gabion. I dug-down about 6-inches into the wash then across about one foot into each side of the bank. The width of the gabion thus was about 10-feet.
I had a roll of heavy-duty wire mesh left-over from another project and used it to contain the rocks. I created two 3'-diameter cylinder with the mesh (each 5-foot in length), laid them in the trench dug in the wash and filled them with rocks. See photos below showing the first section in place.
This wire mesh can be purchased at a building materials store and comes in rolls. WARNING: The wire wants to stay rolled as you try to unroll it flat. Be careful here. If not secured adequately, the end can spring-back at you and cause serious injury. Wear heavy duty gloves and eye protection.