Food for thought ~
Dew capture might be possible, it is surprising how much dew capture happens in drylands. Seems rather invisible, however stone structures or gravel based on top of soil can harvest dew in the night. Any air moisture will get trapped the rocks and as they cool they collect water on the bottom side that is hidden from the open air. If one can incorporate the dew capture materials with your swales or rain capture pattern you get better benefit-as when it does rain the dew capture structure will hold moisture longer by the same shading effect adding more air moisture right there-to be re-captured in the night.
Hypothetically, on a larger scale, if there was a way to arrange dew capture features continuously just below peaks and ridges (that are now barren) those ridges and peaks could be replanted with the right species(perhaps a native tree or shrub combo), these are selected because they also harvest and enhance dew capture, if this is done at scale it might actually increase localized rain potential and for every storm event that passes. The system will harvest dew from the air even if only traces of rain occur.
If situated in a valley and the wind blows generally sideways across the valley bottom, one could add contours shaped exactly against the predominant wind (like a series of long loess dunes) Snow or rain capture fencing is added to the cornice side of each ridge, effectively scraping the wind and creating a small pressure drop on those ridges. If in snow country, the fencing really does it's thing! Add dew capture features below the wind scraping fences and native dew enhancing tree/shrubs near the top edge of the ridge.
On a an even larger scale, really really big! if the above methods worked... Then perhaps an enormous contour system of rain capture lakes/ponds is installed generally at the toe of the slope around an entire valley.
Very heavy lifting for the bigger stuff.
