Maybe not online, but check out Pelle Soeborg’s articles in MR. Yeah, I know, it’s not Utah, but his scenery techniques can be adapted for anywhere in the southwest.
Note that the photos you linked to are not technically in the “desert” but are either in the Wasatch Mountains (various parts of the Price River canyon) or the very eastern fringe of the Wasatch Plateau around Utah Railway’s Martin yard. These places may have a pretty harsh climate but aren’t dry enough to qualify as desert. Of course to modelers living in the East or Pacific Northwest they still look pretty barren.
I like these places so much that i went on vacation to these exact places and took tupperware bowls full of soil samples that will be used on my layout after sifting them thru a tea strainer…The soil from Utah is the best…it’s an orange tan color and is perfect for southwest scenery modeling…Chuck