One method that may be useful for experimenting with currants in a dry region is the practice of pit-and-mound plantings. Just upslope of where you intend to plant them, dig a small hole and tamp down the bottom and sides to create a basin. It can help to add water during this step, and it will give you the ability to see how the rate of percolation (the draining of the water through the soil) changes. The goal of this method is to catch as much of the precipitation as possible and release it slowly and locally to a particular plant. This will give that plant a longer period of water availability which could help to mitigate the general lack of rain.

Since currants propagate readily from mounding, or stool layering (if you're looking for other plants this will work with), you can use the soil you dug to build up soil against the stems. Alternatively, you can use the removed soil to create small half rings on the downslope side of them to create additional space to hold water. If you decide to mound the soil, be sure to make the top as flat and level as you can to allow water to soak in instead of running off too quickly.