Volcanic eruptions can affect river flow
24 Nov 2015 by hjqbcptqcm.d hjqbcptqcm.d
Major volcanic eruptions have been found to affect the flow of the world’s biggest rivers.
Major volcanic eruptions have been found to affect the flow of the world’s biggest rivers.
Scientists at the University of Edinburgh analysed flow records in 50 major rivers and discovered that big volcanic eruptions can trigger a shortage of rainfall in many regions of the world and impact flow.
Dr Carley Iles of the University of Edinburgh’s School of GeoSciences, who led the research, said: “Our findings reveal the indirect effect that volcanoes can have on rivers, and could be very valuable in the event of a major volcanic eruption in future.”
The team analysed observational records of streamflow volume for 50 large rivers from around the world following six major volcanic eruptions in the 20th and late 19th century. By using computer models they studied the impact of a process in which volcanoes release aerosol particles that reflect sunlight, cooling the atmosphere and reducing rainfall.
“Stratospheric volcanic aerosols reflect sunlight, which reduces evaporation, whilst surface cooling stabilises the atmosphere and reduces its water-holding capacity. Circulation changes modulate this global precipitation reduction on regional scales,” the researchers said in their paper.
The results, published in the journal Nature Geoscience, showed significant reductions in flow following eruptions for the Amazon, Congo, Nile, Orange, Ob, Yenisey and Kolyma rivers. Furthermore, data from neighbouring rivers confirmed a significant decrease in streamflow following eruptions in northern South American, central African and high-latitude Asian rivers, and on average across wet tropical and subtropical regions.
Moreover, the scientists detected an increase in flow in southern South American and southwestern North American rivers as a result of atmospheric circulation disruption. They suggest future volcanic eruptions could substantially affect global water availability.
Next, the researchers hope to predict changes in river flow followed by volcanic eruptions.
Paper: http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2545.html
