Droughts & heatwaves worldwide threaten water security: Study

Increased demand for water due to global population growth, coupled with the increasing frequency of extreme weather events, endangers global water security, warns a study.

Little is known about the relationship of water use by sectors and the occurrence of drought-heat-wave events, particularly at the large scale.

Researchers from Utrecht University in the Netherlands, evaluated the responses of sectoral water use -- how the water use practices of sectors namely domestic, irrigation, thermoelectric energy, manufacturing and livestock are affected by the occurrence of droughts, heat waves and compound events -- at a global scale from 1990-2019. 

The findings, published in Environmental Research Letters, shows that stronger sectoral water use responses are found for heat waves compared to impacts during droughts.

The analysis shows that extreme events over the last 30 years had substantial impacts on water use patterns, but these responses highly differ per sector and region across the world.

"Socio-economic factors and public water management plans strongly influence water use responses, and even more so during extreme events. For instance, while Western continental United States decreases its water use during extremes, the central US increases it," said lead author Gabriel Cardenas Belleza, doctoral candidate at Utrecht University in the Netherlands.

In addition, the results reveal that the domestic and irrigation sectors, in general, have the highest priority for water use worldwide, however, stricter measures are taken in favour of the domestic sector during extremes.

The analysis also shows that heat waves and compound drought-heat wave events overall have stronger impacts on water use in comparison to solely droughts. 

"Heat waves and compound events can lead to higher water use as a consequence of the temporary increase in water demand under high temperatures, which can still be satisfied due to the short duration of such extremes, compared to longer-lasting events like droughts," Belleza said.

The results of the study demonstrate the urgency of collecting more water use data to better understand the implications of extreme events and climate change on different water use sectors and for improved assessments of future water scarcity.

"Our research provides a first step to evaluate multi-sectoral water use behaviour during extremes. However, more local-scale information from data-scarce areas, like Africa and parts of Asia and South America, is needed to better understand sectoral water use behaviour and improve water management strategies," Belleza said.