Sometimes it seems like one of our favorite collective pastimes is the creation of dams. We use them to collect water, to generate hydropower, to control unhappy flooding, and inadvertently drown archaeological sites. But are they really worthwhile? Fred Pearce in NewScientist (24 June 2017) reports on research on that topic:
Almost a quarter of the global population experiences significant decreases in water availability through human interventions on rivers, says Ted Veldkamp at Vrije University in Amsterdam, the Netherlands. Those interventions primarily involve dams that take water for irrigation or hydroelectricity, or to supply cities.
Veldkamp and her colleagues created a detailed modelling study to assess water scarcity between 1971 and 2010. The team found a drastic reshuffling of scarcity hotspots over time, with mostly people upstream benefiting from the damming of river flows, but those downstream left high and dry (Nature Communications, doi.org/b8rs).
The world has spent an estimated $2 trillion on dams in recent decades. But Veldkamp’s startling conclusion is that it has left 23 per cent of the global population with less water, compared with only 20 per cent who have gained.
Which suggests that dams – like most human activities – are about using political power for personal advantage, whether it be the gratification of building something big, or the financial advantages of controlling water supplies. Perhaps future proposed dams should be required to show they will result in better water availability for more people before they receive their permits to build.
