With all due respect, this article indicated two factors leading to national water stress, the first is the currently recognized changes in rainfall patterns. The second is the political/population aspect to those nations. In many cases, it is not a total lack of water resources that will affect the population, but its distribution within the country and the lack of infrastructure or political will/means to match the distribution of water to the distribution of usage.
While many might focus on the "man-made" side of the issue regarding the changes in water distribution, the far far greater calamity is the 100% man-made factors that make up the political problems.
The US has unmatched monetary resources to easily manage the water distribution changes caused by changes to the climate, regardless of their cause. However, the political environment makes usage of those monetary resources to change the water usage distribution to match the future water resource distribution impossible. And sadly, there is next to zero chance of any change in the collective political will to alter US use of water to match future water distribution.