For extreme drought, which is anything under 350mm rain a year.
I think you need extensive alternative methods, when there really isn't enough rain.
1st, above surface storage is the lest effective storage, due to evaporation that can cause significant losses, so underground storage for desert areas is a must.
Next best option I would suggest is desalination. This of course depends on the closeness to the sea, but if feasible, this is a very practical, simple anc cheap method. They have a great system in, I want to say Ghana...? Not sure, but around that area..
Latly, is catching the morning dew in designated blankets, with under tanks to store the water as it condenses.
This is a very inefficient method, and should be used only to bolster other existing systems.
In general, for areas that are too desertified already, the only real viable option long term is large scale reforestation of the land, along with proper earth works and water ways. This will eventually bring back the rain to the landscape, but obviously is beyond the scope of one individual, and is more governmental responsibility.
Thanks for the insight as always, Orlev.