Observations and modeling of San Diego beaches during El Nino

TitleObservations and modeling of San Diego beaches during El Nino
Publication TypeJournal Article
Year of Publication2016
AuthorsDoria A., Guza RT, O'Reilly W.C, Yates M.L
JournalContinental Shelf Research
Volume124
Pagination153-164
Date Published2016/08
Type of ArticleArticle
ISBN Number0278-4343
Accession NumberWOS:000382346900014
Keywordsclimate; coastal; equilibrium; erosion; framework; LiDAR; littoral cell; pacific-northwest; sea-level rise; shoreline change; wave
Abstract

Subaerial sand levels were observed at five southern California beaches for 16 years, including notable El Ninos in 1997-98 and 2009-10. An existing, empirical shoreline equilibrium model, driven with wave conditions estimated using a regional buoy network, simulates well the seasonal changes in subaerial beach width (e.g. the cross-shore location of the MSL contour) during non-El Nino years, similar to previous results with a 5-year time series lacking an El Nino winter. The existing model correctly identifies the 1997-98 El Nino winter conditions as more erosive than 2009-10, but overestimates shoreline erosion during both El Ninos. The good skill of the existing equilibrium model in typical conditions does not necessarily extrapolate to extreme erosion on these beaches where a few meters thick sand layer often overlies more resistant layers. The modest over-prediction of the 2009-10 El Nino is reduced by gradually decreasing the model mobility of highly eroded shorelines (simulating cobbles, kelp wrack, shell hash, or other stabilizing layers). Over prediction during the more severe 1997-98 El Nino is corrected by stopping model erosion when resilient surfaces (identified with aerial imagery) are reached. The trained model provides a computationally simple (e.g. nonlinear first order differential equation) representation of the observed relationship between incident waves and shoreline change. (C) 2016 Elsevier Ltd. All rights reserved.

DOI10.1016/j.csr.2016.05.008
Short TitleCont Shelf Res
Student Publication: 
No