Colorado River Basin: Climate change scenarios and reservoir depletion risk

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From the Science Blog:

The research team examined the future vulnerability of the system to water supply variability coupled with projected changes in water demand. The team found that through 2026, the risk of fully depleting reservoir storage in any given year remains below 10 percent 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 percent reduction in the Colorado River’s average stream flow as some recent studies predict, the chances of fully depleting reservoir storage will exceed 25 percent by 2057, according to the study. If climate change results in a 20 percent reduction, the chances of fully depleting reservoir storage will exceed 50 percent by 2057, [Balaji Rajagopalan, a CU-Boulder associate professor of civil, environmental and architectural engineering] said…

Total storage capacity of reservoirs on the Colorado exceeds 60 million acre feet, almost 4 times the average annual flow on the river, and the two largest reservoirs — Lake Mead and Lake Powell — can store up to 50 million acre feet of water. As a result, the risk of full reservoir depletion will remain low through 2026, even with a 20 percent stream flow reduction induced by climate change, said Rajagopalan.

Between 2026 and 2057, the risks of fully depleting reservoir storage will increase seven-fold under the current management practices when compared with risks expected from population pressures alone. Implementing more aggressive management practices — in which downstream releases are reduced during periods of reservoir shortages — could lead to only a two-fold increase in risk of depleting all reservoir storage during this period, according to the study.

More Coyote Gulch coverage here.

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