As California grapples with the effects of an ongoing drought, UC Berkeley researchers are studying changes in the magnitude of streamflows and drought-induced tree mortality in order to advise climate change policy.
Laurel Larsen, campus associate professor in the department of geography, is the lead scientist of the Delta Stewardship Council and provides data that informs the council’s decisions on water management in the Sacramento-San Joaquin Delta.
According to the Delta Stewardship Council website, the council aims to ensure a reliable water supply throughout the state and “a healthy and protected ecosystem.”
“With the drought that we’re in now, there’s been a lot of focus on the immediate short term,” Larsen said. “How do we balance the need to balance these water rights and allocations with the need to protect the delta and the endangered species that we manage water resources for?”
Larsen also oversees the Environmental Systems Dynamics Laboratory in the campus department of geography. The group studies the water cycle and its impact on ecosystem services.
She added that one aspect of the research conducts centers around what drives increases or decreases in streamflow.
With regards to the drought, Liang Zhang, a campus student researcher, conducted an extreme event analysis and found that decreases in the magnitude of streamflows are related to warmer conditions and reduced precipitation, according to Larsen.
“Drought has been and will continue to increase in severity because these years with anomalously low precipitation are accompanied by anomalously high temperatures,” Larsen said. “Our work is helping us characterize how drought is impacting streamflow.”
To better understand and predict streamflow, the group is employing emerging tools from data science, according to Larsen.
Anthony Suen, director of programs at the campus Division of Data Sciences, provided one example of a tool that can be used to make predictions in the area of climate change: geospatial modeling.
Suen said geospatial modeling can determine trends in freshwater areas globally and can predict how climate change will impact the future.
Alexis Bernal, a campus research assistant at the Stephens Lab, noted that droughts and wildfires “go hand in hand.” She is currently working on a research project that focuses on the causes behind the burn severity patterns in the giant sequoia groves during the fires in 2020.
According to Bernal, one hypothesis about what contributed to the severity of wildfires is that drought-related tree mortality has turned some trees into fuel dry enough to burn because of a hotter climate. She added that her research can help inform land managers on how to promote conservation and ensure that the groves are resilient to drought and fire.
“For trees that have survived so many droughts and so many fires to live to be that size and be thousands of years old, to die in a single fire is really astonishing,” Bernal said. “It’s a reality check. This isn’t supposed to happen.”
