All the reservoirs along the Colorado River might dry up by mid-century as the climate continues to warm. A study by the American Geophysical Union (AGU) and the University of Colorado has been looking into the effects that a range of reductions in Colorado River stream flow might have on future reservoir levels and at the implications of different management strategies.

“This study, along with others that predict future flow reductions in the Colorado River Basin, suggests that water managers should begin to re-think current water management practices during the next few years, before the more serious effects of climate change appear,” says lead study author Balaji Rajagopalan of the University of Colorado in Boulder (CU-Boulder).

The findings by Rajagopalan and his colleagues have been accepted by the journal Water Resources Research, which is published by the American Geophysical Union.

According to their findings, even under the harshest drying caused by climate change, the capacity of the reservoirs might sustain water supply for a few decades. However, new management approaches are necessary to minimize the chances of fully depleting the reservoirs by mid-century.

The Colorado River system is enduring its 10th year of a drought. Fortunately, the river system entered the drought in 2000, with the reservoirs at approximately 95% of capacity. The reservoir system is currently at 59% of capacity, about the same as this time last year, says Rajagopalan. Roughly 30 million people depend on the Colorado River for drinking and irrigation water.

The research team examined the future vulnerability of the system to water supply variability coupled with projected changes in water demand. They found that through 2026, the risk of fully depleting reservoir storage in any given year remains below 10% under any scenario of climate fluctuation or management alternative. During this period, the reservoir storage could even recover from its current low level, according to the researchers.

But if climate change results in a 10% reduction in the Colorado River’s average stream flow, as some recent studies predict, the chances of fully depleting reservoir storage will exceed 25% by 2057, according to the study. If climate change results in a 20% flow reduction, the chances of fully depleting reservoir storage will exceed one in two by 2057, Rajagopalan says.


- Katrice R. Jalbuena

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Sources:

¹ http://www.agu.org/sci_soc/prrl/2009-20.html
² http://www.agu.org/