This week, the Community Alliance for Surveying the Topography of Sandy Beaches (CoAST SB) has launched a new website that shares seven years of data — offering a clearer picture of how Southern California’s beaches have been changing.
CoAST SB is a citizen science program sponsored by California Sea Grant. Once each month, teams of volunteers measure the shapes of key beaches in Santa Barbara and Ventura counties, noting the width and slope of the beach.
The new website features three-dimensional visualizations of how the shape of the counties’ beaches has changed over time, as well as more information about how data collected by the program is used. Previously, these results and data have been shared with agencies, such as the US Geological Survey, but they have not been widely available to the public.
“A big part that we’ve been missing is being able to share the information that’s been collected over all these years,” says Carolynn Culver, the California Sea Grant Aquatic Resources Specialist who co-founded and directs CoAST SB.
The shape of a beach changes naturally throughout the day and year, but humans can have major impacts too. Structures like seawalls are meant to protect the coastline from flooding and erosion but can prevent new sand from being deposited on a beach. Changes on land or in the watershed that feeds a beach can directly impact how much sand is delivered to the coast. As sea levels rise, more sand is expected to be lost, narrowing beaches. A USGS model suggests that as much as two-thirds of California’s beaches may be lost by 2100 under worst-case sea-level rise scenarios.
The data collected by CoAST SB is in some ways “low-tech”: Volunteers take measurements along a consistent transect using nothing more than two measuring sticks linked by a three-meter rope. “But just from these very simple ways of surveying, you’re able to capture these really important patterns in a beach,” says Jenna Wisniewski, the survey’s program manager and web designer.
USGS and local governments use the data to evaluate impacts from storm events. For example, CoAST SB volunteers helped supply some of the first scientific data about how a major 2018 debris flow impacted local beaches. Culver believes the data can be even more widely used, and hopes that the website will help interested researchers access the surveys’ results.
Photo caption: From left to right, volunteers Pyp Pratt, Rali Kirova and Paul Pratt conduct a measurement at Arroyo Burro Beach County Park.