SEA LEVEL RISE

The Los Angeles County Department of Beaches and Harbors (LA County) operates and maintains 19 public beaches along Pacific Ocean coastline (mostly in Santa Monica Bay), between City of Malibu and San Pedro, a coastal community within City of Los Angeles.  The unique urban setting of Los Angeles County shoreline is one of the most valuable coastal resources in California.  Its regional beaches provide recreation and enjoyment for upwards of 70 million of visitors annually.

Because of forecasts on rising sea levels due to climate change, LA County initiated a process of proactive preparedness by assessing the potential threat that its public beach assets may face through year 2100.  The Sea-level Rise Vulnerability Assessment presents an overview of existing LA County beach settings, assesses the potential threat that future sea-level rise may pose on recreational assets, and introduces appropriate strategies to be considered to begin a dialog on how best to address the forecasts.  Such strategies consist of continued use of temporary sand berm program for short term management, beach nourishment for future management, and possible natural dunes, elevated foundations or even retreat as long term management.

Due to a range of sea-level rise forecasts relevant to the California coast, the assessment summarizes the projections from prominent studies, particularly three from the National Oceanic and Atmospheric Administration’s Climate Program Office, the National Research Council, the Intergovernmental Panel on Climate Change, and includes potential vulnerability forecasts of the Los Angeles County shoreline as projected in a coastal storm modeling system (CoSMos) study by the US Geological Survey (USGS).

The assessment summarizes LA County’s beach assets and argues that the lack of certainty on how high sea-level will rise and when it will occur makes it difficult to adopt implementation plans now for the future.  It also suggests that an adaptive management strategy may provide the most appropriate path to address how best to maintain existing assets and respond to future conditions as certainty becomes more focused.