Climate has always produced fresh water in a given location that varies with the climatic cycles be it PDO, Nino, Nina etc. The one thing man has done is grow in population and as a result needs more water for themselves nad for growing the food we need to survive. If that population grows by 20% in a given location and in the past it was just able to cope during the dry cycles when the next dry cycle appears with that 20% increase in place don't expect the area to cope. This isn't down to climate change its down to population growth. The issue of water supply is far far more complex than being presented here and isn't worthy of this thread.