Human water consumption intensifies hydrological drought worldwide

Over the past 50 years, human water use has more than doubled and affected streamflow over
various regions of the world. However, it remains unclear to what degree human water
consumption intensifies hydrological drought (the occurrence of anomalously low
streamflow). Here, we quantify over the period 1960–2010 the impact of human water
consumption on the intensity and frequency of hydrological drought worldwide. The results
show that human water consumption substantially reduced local and downstream streamflow
over Europe, North America and Asia, and subsequently intensified the magnitude of
hydrological droughts by 10–500%, occurring during nation- and continent-wide drought
events. Also, human water consumption alone increased global drought frequency by 27
(±6)%. The intensification of drought frequency is most severe over Asia (35 ± 7%), but also
substantial over North America (25 ± 6%) and Europe (20 ± 5%). Importantly, the severe
drought conditions are driven primarily by human water consumption over many parts of these
regions. Irrigation is responsible for the intensification of hydrological droughts over the
western and central US, southern Europe and Asia, whereas the impact of industrial and
households’ consumption on the intensification is considerably larger over the eastern US and
western and central Europe. Our findings reveal that human water consumption is one of the
more important mechanisms intensifying hydrological drought, and is likely to remain as a
major factor affecting drought intensity and frequency in the coming decades.