This study is the first comprehensive publication of tidal datums and extreme tides for San Francisco Bay (Bay) since the United States Army Corps of Engineers (USACE) published itsSan Francisco Bay Tidal Stage vs. Frequency Study in 1984 (USACE 1984). The USACE study was groundbreaking at the time of publication, presenting tidal datums and the “100-year tide” elevation for 53 locations around the Bay. The purpose of this study is to update and expand on the USACE study and to present daily and extreme tidal information for more than 900 locations along the Bay shoreline. Tidal datums, described further in Section 2 , are standard elevations defined by a certain phase of the tide (e.g., mean high tide, mean low tide). A tidal datum is used as a reference to measure and define local water levels, and as such is specific to local hydrodynamic processes and is not easily extended from one area to another without substantiating measurements or analysis. Many industries and activities rely on tidal datums, including shipping and navigation, coastal flood management, coastal development, and wetland restoration. Extreme tidal elevations are estimated for less-frequent extreme tides (e.g., 2-year tides to 500-year tides [tides with a 50.0 percent to 0.2 percent annual chance of occurrence, respectively]). Knowledge of the 100-year tide, or the water elevation with a 1 percent annual chance of occurrence, is critical for shoreline planning, floodplain management, and sea level rise (SLR) adaptation efforts. This study presents detailed daily and extreme tide information for the entirety of the Bay shoreline. This data set will support floodplain management efforts; shoreline vulnerability and risk analyses; shoreline engineering, design, and permitting; ecological studies; and appropriate sea level rise adaptation planning. The goal of this study is to provide data that support a wide-range of planning efforts around the Bay, particularly as communities seek to understand—and begin to adapt to—rising sea levels. You can access the full report at: http://www.adaptingtorisingtides.org/wp-content/uploads/2016/05/20160429.SFBay_Tidal-Datums_and_Extreme_Tides_Study.FINAL_.pdf.

Knowledge of the 100-year tide, or the water elevation with a 1 percent annual chance of occurrence, is critical for shoreline planning, floodplain management, and sea level rise (SLR) adaptation efforts. This study presents detailed daily and extreme tide information for the entirety of the Bay shoreline. This data set will support floodplain management efforts; shoreline vulnerability and risk analyses; shoreline engineering, design, and permitting; ecological studies; and appropriate sea level rise adaptation planning. The goal of this study is to provide data that support a wide-range of planning efforts around the Bay, particularly as communities seek to understand—and begin to adapt to—rising sea levels.

Abstract

The San Francisco Bay Conservation and Development Commission (BCDC) is a California state planning and regulatory agency with regional authority over the San Francisco Bay, the Bay’s shoreline band, and the Suisun Marsh. BCDC was created in 1965 and is the nation’s oldest coastal zone agency. The tables included provide information on community vulnerability to current and future flooding; a shoreline vulnerability index for the San Francisco Bay Shoreline; and information on tidal datums.

Methodology

Detailed descriptions of the tables provided:

1. Community Vulnerability: The San Francisco Bay Conservation and Development Commission Adapting to Rising Tides Program developed a dataset to better understand community vulnerability to current and future flooding due to sea level rise and storm surges. This data has been used in the Adapting To Rising Tides Bay Area Sea Level Rise Vulnerability and Assessment project as well as helping inform the implementation of the BCDC Environmental Justice and Social Equity Bay Plan amendment.

2. SF Bay Tidal Datums: The tidal datums and extremetides study is the first comprehensive publication of tidal datums and extreme tides for San Francisco Bay (Bay) since the United States Army Corps of Engineers (USACE) published itsSan Francisco Bay Tidal Stage vs. Frequency Study in 1984 (USACE 1984). The purpose of this study is to update and expand on the USACE study and to present daily and extreme tidal information for more than 900 locations along the Bay shoreline.

3. Shoreline Vulnerability Index: This San Francisco Bay Shoreline Vulnerability Index is a measure of shoreline vulnerability to erosion and/or overtopping due to extreme tides, waves, storm surges, and sea level rise. The Index gives a comprehensive look at how different sections of the Bay respond to storm surge, erosion from waves, and sea level rise.