The study, which was published in the Canadian journal Atmosphere-Ocean, looked at the effects of climate warming on stream flow in the headwaters and downstream reaches of seven sub-basins of the Columbia River from 1950 to 2010. The researchers found that the peak of the annual snowmelt runoff has shifted to a few days earlier, but the downstream impacts were negligible because reservoir management counteracts these effects.
"The dams are doing what they are supposed to do, which is to use engineering - and management - to buffer us from climate variability and climate warming," said Julia Jones, an Oregon State University hydrologist and co-author on the study. "The climate change signals that people have expected in stream flow haven't been evident in the Columbia River basin because of the dams and reservoir management. That may not be the case elsewhere, however."
The study is one of several published in a special edition of the journal, which examines the iconic river as the United States and Canada begin a formal 10-year review of the Columbia River water management treaty in 2014. The treaty expires in 2024.
Jones said the net effect of reservoir management is to reduce amplitude of water flow variance by containing water upstream during peak flows for flood control, or augmenting low flows in late summer. While authorized primarily for flood control, reservoir management also considers water release strategies for fish migration, hydropower, ship navigation and recreation.
These social forces, as well as climate change impacts, have the potential to create more variability in river flow, but the decades-long hydrograph chart of the Columbia River is stable because of the dams, said Jones, who is on the faculty of the College of Earth, Ocean, and Atmospheric Sciences at OSU...
The Grand Coulee Dam on the Columbia River, shot by United States Bureau of Reclamation, public domain
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