Key points from article :
Early warning satellite system reveals countries with shrinking reservoirs.
Spain, Morocco, India and Iraq at risk of taps completely drying up.
Morocco’s second-largest reservoir has shrunk by 60% in three years.
Water is now at the lowest level in a decade.
Irrigation halted in part of India to preserve drinking supply for 30 million people.
Spain has suffered a severe drought that has hit hydropower generation.