Arizona is certainly not a water rich wonderland. With all our up and down terrain, when we do get rain (often in short but sweet torrents), paths are quickly cut into the earth. Forest roads are maintained minimally at best; evidence of last season's moisture is almost always present. This is a section of the Senator Highway near Crown King.
Even my street, one of the town's last dirt roads, is quickly eroded by water. The recent run-off has cut down to a thin caliche (lime) layer two or three inches below the surface.
No surprise that steep road cuts are open invitations to rapid erosion. Now that I look at all my pictures, the most evident erosion takes place where road builders have been at work.

The white sluice (above) from a higher road does not stop the rain from making its own paths through this Verde Valley alluvial soil.
The best example of how fast water can work is at the Lowe's Open Pit. Take a look the next time you speed by on SR69 -- that poor hillside has been gouged by recent rains despite the grid of erosion control measures.
Apparently this device is a fiber matrix log, installed to slow run-off down a small wash on a slope over at Embry Riddle. (I got the terminology from the Erosion Control Technology Council -- believe me, I was fumbling for the right words.)
The Japanese-style stone stream next the sidewalk at Prescott College is a working erosion control measure. Miller Valley Road is sloping down toward Butte Creek at this point. Most such stonework I've seen around town is similarly practical, not just decorative.
More matrix logs, here protecting a construction site on the Yavapai rez on the south side of SR69. Not that erosion is necessarily a Bad Thing. After all, consider the crowds who visit the Grand Canyon or Oak Creek Canyon. Now that's Big Time Erosion.Note: I just read Lucy's soliloquy on the seasons. Lovely pictures, thoughtful. Visit her at Box Elder.