Researchers from the University of Edinburgh’s School of GeoSciences recently published the first study of its kind in Nature Geoscience, documenting changes to the water volume of large rivers following substantial volcanic eruptions.
A year or two following volcanic eruptions, EurekAlert! reports, river water flow either increases or decreases, depending on the climate where the eruptions occur. Researchers looked at long-term records that measured the flow of fifty major rivers around the world, and charted the rivers’ water volume in relation to nearby volcanic eruptions. In general, river flow in wet tropical regions decreased, sometimes by as much as 10 percent (such as in the Nile, Amazon, and Congo regions); whereas river flow in drier subtropical regions increased, sometimes by as much as 25 percent (such as in areas of the Southwestern United States and in parts of South America).
According to New Scientist, when volcanoes erupt they release aerosol particles into the atmosphere. These particles reflect sunlight, which leads to cooling and decreased rainfall. Additionally, these atmospheric changes can interfere with the Hadley cell, which is the name given to certain atmospheric circulation patterns. The circulation patterns rise near the equator and descend in the subtropics. The major driving force of the Hadley cell is atmospheric heating from the sun, but circulation patterns can be impacted by various geological events.
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.
Dr. Carley Iles, who led the research, says, “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 researchers’ findings will aid in predicting likely river flow changes following future volcanic eruptions, and will also help countries plan for the effects of these changes on human and agricultural water supply.