Southern California’s beaches have expanded by more than 500 acres over the last 40 years, according to a recent study led by researchers from the University of California, Irvine, the U.S. Geological Survey (USGS), and other institutions. The findings were published in Nature Communications.
The research used satellite-derived measurement methods to analyze shoreline changes in California between 1984 and 2024. Contrary to previous beliefs that urban development and damming would lead to significant erosion, the study found that Southern California’s beaches grew by about 10 percent during this period.
“This is a counterintuitive finding considering previous reports of widespread beach erosion in Southern California,” said Brett Sanders, UC Irvine professor of civil and environmental engineering. “While several individual beaches did experience severe erosion, there were also several that experienced dramatic widening, and the overall trend shows widening at an average rate of 7.2 meters across 320 kilometers of Southern California coastline.”
According to the study, 49 percent of the region’s shoreline saw significant widening while 31 percent narrowed. Some areas experienced notable erosion: for example, Zuma littoral cell near Malibu and northern parts of Oceanside littoral cell—including Doheny, San Clemente, and San Onofre—lost over one meter per year on average.
The growth was most prominent at locations with human-made coastal structures like harbors and jetties or at natural sand convergence zones. Notable rapidly expanding beaches include Huntington Beach and Santa Monica as well as less visited stretches such as between Ventura and Oxnard.
The study also compared three regions—northern, central, and southern California—with southern California showing a strong positive trend in beach area; northern California showed moderate growth; central California saw no significant change.
“The primary challenge facing Southern California beaches is not sediment shortage, but sediment distribution,” said Jonathan Warrick, research geologist at USGS Pacific Coastal and Marine Science Center in Santa Cruz. “Some of the most rapidly widening beaches – including McGrath State Beach, Huntington Beach, and Venice Beach – now measure approximately 200 meters, or over 600 feet wide. These locations benefit from sediment trapped by coastal structures or accumulating in natural sand convergence zones.”
Researchers credited newly developed satellite data for enabling more accurate monitoring compared to older field surveys or limited aerial scans. “These new tools are revolutionizing how we assess beaches and their changes,” Sanders said. “Beaches were previously monitored by field crews using surveying equipment or with aerial flights that scan the coast with laser surveys but the costs … limited frequency … Satellite imagery now allows us to measure beach width everywhere several times per month.”
The study suggests opportunities for improved coastal management through strategic redistribution rather than increasing sediment supply overall. Existing programs move sand past barriers at several harbors—including Santa Barbara, Ventura, Channel Islands/Port Hueneme—and could be expanded for broader benefits.
One example highlighted is the San Pedro littoral cell—which includes Sunset Beach, Huntington Beach and Newport Beach communities—where engineered projects led to an average increase in beach width of about 25 meters (over 80 feet) across four decades.
While large dams have reduced natural sand flow to half historic levels statewide due to river blockage upstream ([source](https://www.usgs.gov/programs/cmhrp/news/californias-beaches-have-grown-last-40-years)), other factors such as bluff erosion or mechanical addition of sand have helped sustain or grow many beaches.
Despite these findings on management possibilities using modern technology ([source](https://floodlab.eng.uci.edu/)), challenges remain including funding constraints, regulatory hurdles, institutional inertia and political boundaries.
“These data give us a much-needed systems perspective of beach dynamics making it easier to find entry points required for effective management,” Sanders added.
Other contributors included Kilian Vos (OHB Digital Services), Daniel Buscombe (Washington Department of Ecology), Andrew Ritchie (USGS), Sean Vidousek (USGS), Teresa Hachey (UC Irvine). The project received funding from USGS and NASA.
