You could add some pea gravel,rock to repress the sand and form a river bed garden.plant bescborneria, agaves,asparagus,gladiolus,pulmonarya,yucca...and interplant hostas,rosemary...but some my friends often mess to plant them,careful.if need,I could take time to design some visual pics for you.

You will likely need an engineer to design the resulting 5 ft high retaining walls.

check the link below, there are several slopes done different ways. Austin, TX gets more rain than you do so you should rely on plants that grow well for your area.

click this link:
before and after photos page 2 has a good one

I did a search on this forum for "slope" and several threads showed up. Read through them all to get some ideas you might be able to use.

Here is a link that might be useful: Slope threads

Anyone recommending large soft leaved woodland habitat plants such as Hostas or Beschornerias for high desert conditions obviously doesn't have a clue about desert landscaping. Similarly thinking that a pond/waterfall feature so exposed to the elements seems futile, or at the least expensive in time and money to keep functioning. Water features would make much more sense in a protected from wind and brutal sun within a courtyard garden.

Erosion control in high desert conditions is as much about wind erosion and the sporadic torrential cloudburst which dumps intense rain over a short period of time. As such, local professional expertise and knowledge of your soil type is critical for efficiently addressing the best approach for ersion control. I'd recommend using adapted native and hardy exotic plants of lowest water use to stabilize those slopes with some grading to bank rainfall to percolate into the soil where possible. Again, visiting local water agency water conservation demonstration gardens would be most useful in helping be more pragmatic about landscaping your high desert back yard.