In a study released today, U.S. Geological Survey scientists and their colleagues, including Timu Gallien, UCLA assistant professor of civil and environmental engineering, document how the 2015-16 winter featured one of the most powerful El Niño climate events of the last 145 years. Investigating 29 beaches along the U.S. West Coast from Washington to Southern California, researchers found that winter beach erosion was 76 percent above normal, by far the highest ever recorded, and most beaches in California eroded beyond historical extremes. If severe El Niño events such as this one become more common in the future as studies suggest, this coastal region, home to more than 25 million people, will become increasingly vulnerable to coastal hazards, independently of projected sea level rise.
The authors assessed seasonal changes on 29 beaches along approximately 2,000 kilometers (1,243 miles) of the U.S. West Coast. Surveying the beaches included making 3-D surface maps and cross-shore profiles using aerial lidar (light detection and ranging), GPS topographic surveys, and direct measurements of sand levels, combined with wave and water level data at each beach, collectively spanning 1997-2016. Winter beach erosion or the removal and loss of sand from the beach is a normal seasonal process, but the extent of erosion can be more severe during El Niño events than in other years.
Gallien, who combines field observations and numerical analysis in her research on coastal hazards, was responsible for collecting and analyzing erosion data from Southern California sites. The full report, “Extreme oceanographic forcing and coastal response due to the 2015-16 El Niño,” was published online in Nature Communications.
To read the full U.S.G.S. news release, click here.
Image credit: Christine Hegermiller, U.S. Geological Survey. Public domain.