November 19, 2015
For more than a decade, UC Berkeley assistant professor and Hertz Fellow Laurel Larsen has air-boated through the peat marshes, wet prairies, and mangrove swamps of Florida’s Everglades, on a mission to discover how the complex mosaic of landscapes sustains itself, and how the fragile ecosystem can continue to provide functions that humans value for the foreseeable future.
In her many visits to the nation’s largest subtropical wetlands preserve, Larsen has worked to gain a better understanding of the interaction of flowing water and sediment on the landscape, and the implications of minute changes on the environment’s basic functioning. The Everglades are undergoing a 30-plus year, multi-billion dollar restoration effort to rebuild wildlife habitats and re-create natural water flows. As part of the adaptive management approach applied to Everglades restoration, scientific experiments are closely coupled to engineering projects to better inform restoration strategy.
“We really need to know whether or not the taxpayer dollars spent on these projects are being effective and if they’re optimizing our restoration efforts,” Larsen said. “It’s not always clear which of these knobs to tweak in order to get the results we want.”
Using modeling and field work to analyze patterns of flow and sediment transport, Laurel and her team have spent the last ten years evaluating how releases of water can redistribute sediment and restore the landscape structure of the Everglades. Their work contributed to the design of a restoration experiment to remove barriers originally emplaced decades ago for flood control and water purposes, and restore sheet flow to the Everglades landscape.
“When those barriers were put in, people weren’t concerned about the environmental impacts,” Larsen said. “The salinity of the Florida Bay is very dependent on freshwater outflows from the Everglades. It’s important to get the water right in South Florida.”
Larsen is entering the final year of the study, and ultimately, she hopes the research will lead to improved water management in the Everglades. In a broader sense, she hopes her science will lead to better understanding of the impacts of climate and land use change on coastal wetlands and river networks.
Laurel Larsen takes notes on a stream/floodplain restoration project near Lancaster, PA. Stream restoration is used throughout the Chesapeake Bay watershed as a means to reduce sediment and nutrient inputs to the Chesapeake Bay estuary, but with limited success. Some states like Pennsylvania are evaluating whether emerging strategies for stream restoration—such as conversion of the stream valley to a low-energy wet meadow wetland, once abundant throughout the eastern seaboard prior to the Colonial period—will better meet these goals. Laurel's group is working to develop models of the feedback between flow, vegetation, sediment, and landform development to understand the sensitivities of these landscapes and predict their evolving form and function in response to environmental change and human management.
The daughter of a NASA engineer and a wetlands specialist, Larsen has always had a keen curiosity about the relationship between water flow and landscape, dating back to her youth in Central Florida. As a teen, Larsen would often explore a marsh near her own neighborhood by canoe—adventures that would inform her future career path.
“I came to really know and love the landscape of Florida,” Larsen said. “And I developed a concern for how humans were impacting the ecosystem.”
Larsen went on to receive her master’s degree in earth and planetary sciences from Washington University in St. Louis and went off to grad school wanting to combine environmental science with mathematics. She earned her PhD in civil, environmental, and architectural engineering from the University of Colorado in 2008 and began her teaching career at UC Berkeley in 2013 after spending nearly five years as a government scientist with the U.S. Geological Survey.
Now, as head of the university’s Environmental Systems Dynamics Laboratory in Berkeley’s Geography Department, Larsen and her team of researchers are dedicated to studying the links among water flow, sediment transport and the physical, biological, and human components of the environment.
In addition to her research in South Florida, Larsen also is involved in work closer to home. She and her Berkeley team have been analyzing streams in Sonoma County to see where the water is coming from and how water from distinct sources impacts the over-summer survival of local salmon populations.
“We’re trying to understand which of the water quality and quantity factors affect salmon during the dry summer months so we can better manage water resources in times of scarcity,” Larsen said.
Larsen is also working under a CAREER grant from the National Science Foundation to study accretionary land growth in coastal regions such as the Wax Lake Delta in southern Louisiana. In the lab, Larsen and her colleagues have built artificial channels—“flumes”—to examine the interactions between flow and vegetation, and create living laboratories that could be used to better understand the restorative impacts of diversions of the Mississippi River.
“We’ll also be building flumes in the field to extend the physical relationships we’ve resolved in the lab,” Larsen said. “The big picture is that large-scale numerical models are pessimistic about the fate of the Mississippi River Delta. It’s sinking at a rapid rate. My hope is that, by better understanding how coastal marshes help accrete land we will improve the predictions of our ability to reverse land loss through engineering.”
In 2014, Larsen received a $1.5 million grant from the Gordon and Betty Moore Foundation to apply techniques from information theory and dynamical systems analysis to big data sets increasingly being collected through remote sensing, environmental observatories, and sensor networks
“Data availability in the environmental sciences is growing faster than our ability to interpret it,” Larsen said. “There might be more efficient ways to understand environmental feedbacks through data-driven science. By working to expand algorithms to evaluate those causal linkages, we’re hoping to test hypotheses that through technology, we can detect catastrophic shifts in environmental systems before they occur.”
At 32, Larsen said she intends to make her career at Berkeley. Long-term goals include advancement of data-driven research in environmental science, and after reaching tenure, would like to focus her attention on managing wetlands in developing countries, such as Brazil.