Mid‐El Niño erosion at nourished and unnourished Southern California beaches

Abstract

AbstractWave conditions in Southern California during the 2015–2016 El Niño were similar to the 2009–2010 El Niño, previously the most erosive (minimum beach widths and subaerial sand levels) in a 7 year record. As of February 2016, Torrey Pines Beach had eroded slightly below 2009–2010 levels, threatening the shoulder of a major highway. However, Cardiff, Solana, and Imperial Beaches, nourished with imported sand in 2012, were on average 1–2 m more elevated and more than 10 m wider than in 2009–2010. Monthly subaerial sand elevation observations showed that the nourished beaches remained consistently wider than unnourished beaches under similar wave conditions. In contrast to a 2001 nourishment at Torrey Pines built with native sized sand that was removed from the beach face during a single storm, these relatively coarse grained nourishments protected shorelines for several years, and during the significant wave attack of the 2015–2016 El Niño, as of February 2016.