As concerns heat up around predicted losses in average mountain snowpack, UC Merced researchers have launched a new program to study the effects of climate change on the San Joaquin River and the millions of people who depend on it.
"We know the climate is changing," said Thomas Harmon, UC Merced professor of engineering and scientist with the Sierra Nevada Research Institute. "We want to take the next step and see how it will affect people."
As temperatures rise, more precipitation is expected to fall as rain rather than snow, causing lower elevation snowpack to melt faster. This will likely cause mountain runoff to begin flowing significantly earlier in season, according to climate scientists.
Under a $1.5 million National Science Foundation grant, scientists hope to develop a range of predictions as to how flows on the river will be affected by climate change.
On average, the spring melt has started coming early by a week or two, Harmon said. "We know qualitatively that timing of snowmelt will change as warming continues in the Sierra."
At the same time, scientists aim to determine how this and other factors will likely affect irrigation and drinking water use, as well as the surrounding ecosystems.
"We have empirical evidence in hand and will look to explore what our human response should be to these climatic impacts," Harmon said.
It's not clear yet if warming conditions will lead to a decrease in total available surface water, but water agencies will face a number of significant challenges.
Dam storage capacity is of particular concern, Harmon said. "We have what we have and if it's exceeded early then we may have to let water go, water we could have saved and used during the heat of the summer."
More accurate data on river flows will help irrigation districts and other agencies more efficiently deliver water for agriculture and other uses.
"You want to make a better prediction of how much water you will be able to deliver over the summer," said Roger Bales, a scientist with the Sierra Nevada Research Institute. "If you're a water agency, you're going to promise farmers a certain amount of water, and you want to promise them an accurate amount."
The study will be conducted by UC Merced, the Sierra Nevada Research Institute and a team of graduate students over the next three years.
The project will include undergraduate students at UC Merced who will help create a website and a mobile kiosk enabling users to monitor San Joaquin River conditions in real time.
Reporter Joshua Emerson Smith can be reached at (209) 385-2486 or firstname.lastname@example.org