Latest El Nino Brought Unprecedented Erosion To W. Coast Beaches - LA Times
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Teaming up, the scientists made surface maps using a remote-sensing laser technology called light detection and ranging, or LIDAR. They also drove all-terrain vehicles across beaches to perform GPS-based topographic surveys. (Barnard, not the biggest fan of dune buggies, said he took it slow.) That kind of analysis wasn’t possible during the last really big El Niño season in 1997-98, when GPS technology was just coming online, Barnard said. “There was a little bit of data collection back then,” he added, “but now it’s basically cheaper, it’s faster — it’s easier to collect these kinds of data.”
The researchers found that the most extreme waves were about 50% larger than usual during the 2015-16 El Niño season. Consequently, the level of beach erosion was a whopping 76% higher than normal — and 27% higher than any other recorded winter. Barnard and his colleagues had expected this El Niño would be big. They just hadn’t thought it would be quite this big.
“We saw the conditions in the Pacific, but I think we were definitely surprised at the scale of the event — especially in relation to the other two monster El Niños that have always been considered to be the big ones,” he said, referring to the 1982-83 and 1997-98 winter seasons.
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Beaches can also be replenished with new sediment washing down rain-swollen rivers. But in Southern California, the combination of powerful waves and little rain created a worst-case scenario, Barnard said. This situation is one that’s been long in the making, said Robert Guza, a physical oceanographer at UC San Diego’s Scripps Institution of Oceanography who was not involved in the study. “Southern California, we love to build in river floodplains and then say, ‘Holy crap, it flooded,’” Guza said. “Then we dam the rivers for flood control and say, ‘Holy crap, the sand’s not getting to the beaches anymore.’”
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http://www.latimes.com/science/sciencenow/la-sci-sn-el-nino-california-20170214-story.html