San Francisco Bay Area Coastal Study - FEMA Region 9 ... · PDF file2an Francisco Bay Area...
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San Francisco Bay Area Coastal Study California Coastal Analysis and Mapping Project September 2012
Transcript of San Francisco Bay Area Coastal Study - FEMA Region 9 ... · PDF file2an Francisco Bay Area...
San Francisco Bay Area Coastal StudyCalifornia Coastal Analysis and Mapping ProjectSeptember 2012
2 San Francisco Bay Area Coastal Study California Coastal Analysis and Mapping Project | FEMA 3
San Francisco Bay Area Coastal Study and Mapping OverviewThe Federal Emergency management Agency (FEMA) is performing new detailed coastal engineering analyses of the shoreline and coastal areas within the nine counties of: • Alameda• Contra Costa• Marin • Napa• San Francisco• San Mateo• Santa Clara• Solano• Sonoma
Thenewcoastalstudywillreviseandupdatethefloodandwavedatafor the coastal Flood Insurance Study reports and Flood Insurance Rate Maps for each of the above counties.
FEMA’scoastalstudyandmappingeffortsbenefitfromnewtechnologies and coastal data, including the latest 2010 detailed topographic data collected as part of the California Coastal Mapping Program.Thecoastalfloodhazardanalysesuseregional-scalestormsurge and wave models of San Francisco Bay. These models produce time-seriesoutputofwaterlevels,openoceanswells,andwind-drivenwaves at over eight thousand points along the complex San Francisco Bayshoreline.Inputparameterstotheregional-scalemodelsincludeocean tide levels, lower Sacramento River discharges, wind and pressurefields,andvariousriverandcreekdischarges.
The model output from the regional models is used to estimate wave runup and overtopping along the Bay’s myriad of shoreline structures and steep shorelines, as well as overland wave propagation over beaches, marshes, and inland developed areas. These onshore analyses will form the basis for potential revisions to the Base Flood Elevations (BFEs)andSpecialFloodHazardAreas(SFHAs)withinthecoastalareasofthenineBayAreacounties.CoastalHighHazardAreas(ZoneVE)willbemappedwhensupportedbyfloodhazardmodelingresults.
The US Army Corps of Engineers is also conducting coastal analyses within San Francisco Bay, and these studies will be evaluated for compatibility with FEMA’s study and mapping goals.
Following FEMA’s due process and statutory requirements, the BFE’s willbefinalizedinrevisedFloodInsuranceStudyreportsandontheFlood Insurance Rate Maps. FEMA is coordinating with Federal and Stateentities,wewellasregionalandlocalstakeholders.FEMAwillcontinuetocoordinatewiththesestakeholdersasthestudyandmapping efforts progress.
Next Steps, Stay Informed and EngagedAfterFEMA’sreviewandapprovalofthecoastalfloodhazardanalysis,itwillcommencewiththefloodplainmappingonacounty-by-countybasis.FEMAwillscheduleaFloodRiskReviewmeetingwitheachBay Area county during this phase of the study. The goal of the Flood RiskReviewmeetingistoenhancethecommunitiesunderstandingoftheavailablefloodriskdatasets,todiscussstudymethodsandresults,andtoprovideinformationonincreasingriskawarenessandstimulatingmitigationactionsthatcanreducerisk.
To stay up to date with the San Francisco Bay Area Coastal Study, and thecompanionOpenPacificCoaststudy,signupforthequarterlye-bulletin,Coastal Beat, that will include schedule updates, technical articles and facts of interest, and relevant information as the study progresses.Visitwww.r9coastal.org for additional coastal study information. Stay informed and engaged in FEMA’s coastal studies by signing up for RSS feeds from this site to receive updates delivered directlytoyouremailinbox.FEMAwelcomesyourfeedback,questionsand comments.
San Francisco Bay Counties
California Coastal Analysis and Mapping Project
San Francisco Bay Area Coastal Study Mapping Timeline
This publication is an initiative of the Mitigation Division of FEMA Region IX.
National Flood Insurance Program
Discovery Map: Los Angeles County
6 San Francisco Bay Area Coastal Study California Coastal Analysis and Mapping Project | FEMA 7
Coastal Flood Issues in the San Francisco Bay AreaTypes of Flooding
Annual High Tide Inundation (“King Tides”)• Howitworks:KingTidesareabnormallyhighpredictableastronomicaltides
thatoccurapproximatelytwiceperyearwithinSanFranciscoBay.KingTidesarethe highest tides that occur each year and typically exceed 7 ft Mean Lower Low Water (MLLW) at the Presidio tide station.
• ExampleEvents:KingTidesoccureveryyearduringthewinter,typicallyduringthe months of December, January, and February.
• TypesofImpacts:Nuisanceflooding;inundationoflow-lyingroads,boardwalks,andwaterfrontpromenades;canexacerbatecoastalandriverineflooding.
• LocationofImpacts:HWY101off-rampatMillValley,Sausalitowaterfront,andRichardsonBayshorelineinMarinCounty;Embarcaderowaterfront(Pier14)andMarinaareainSanFrancisco;andBayBridgeTollPlazafrontageroadandJackLondonSquareinAlamedaCounty.
El Niño Winter Storms• Howitworks:DuringElNiñowinters,atmosphericandoceanographic
conditionsinthePacificOceanproduceseverewinterstormsthatimpacttheSanFranciscoBayregion.PacificOceanstormsfollowamoresoutherlyrouteand bring intense rainfall and storm conditions to the Bay area. Riverine and coastalfloodingoftencoincideandproduceupstreamflooding.Tidesareelevated by approximately 0.5 to 1.0 feet above normal along the coast and wind setup can elevate water levels even further locally.
• ExampleEvents:Wintersof1977-1978;1982-1983;1997-1998;2009-2010.• TypesofImpacts:Severeinundationoflow-lyingroads,boardwalks,and
waterfrontpromenades;combinedriverineandcoastalflooding;wavedamageto coastal structures.
• Location of Impacts: Throughout the Bay, particularly along developed shorelinesandtidallyinfluencedcreeksandsloughspronetohightideflooding.
Extreme High Tide Inundation • Howitworks:WhenPacificOceanstormscoincidewithhightides,stormsurge
due to meteorological effects can further elevate San Francisco Bay water levels toproduceextremehightides.ElNiñoconditionsalongtheCaliforniacoastcanalso contribute to storm surge and produce extraordinarily high water levels.
• ExampleEvents:January27,1983(8.66ftMLLW);December3,1983(8.65ftMLLW);February6,1998(8.38ftMLLW);January8,2005(8.14ftMLLW);December31,2006(8.09ftMLLW).
• TypesofImpacts:Severeinundationoflow-lyingroads,boardwalks,andwaterfrontpromenades;canexacerbatecoastalandriverinefloodingandcauseupstreamflooding;caninterferewithstormwateroutfalls.
• Location of Impacts: Throughout the Bay, particularly along developed shorelinesandtidallyinfluencedcreeksandsloughspronetohightideflooding.
Wind Wave Events• Howitworks:StrongwindsduetoPacificOceanstormsorstrongthermal
gradients produce strong winds that blow across the Bay. When the wind blows over long reaches of open water large waves can be generated that impact the shoreline and cause damage.
• ExampleEvents:PacificOceanwinterstormevents;pre-frontalsoutherlywinds;northerly thermal winds.
• Types of Impacts: Wave damage along the shoreline, particularly to coastal structuressuchaslevees,docksandpiers,wharfs,revetments;backshoreinundation due to wave overtopping of structures and ponding. Impacts can beexacerbatedbyhightideswhichlimitswavedissipationovermudflatsandmarsh.
• Location of Impacts: Exposed shorelines with expansive wind fetches, particularly along the East Bay shoreline.
Front and Back Cover Photos:Copyright©2010-2011Kenneth&GabrielleAdelman,CaliforniaCoastalRecordsProject,www.californiacoastline.org
www.fema.gov/plan/prevent/fhm/rm_main.shtm·1–877–FEMAMAP
Points of Contact
For more information on the California Coastal Analysis and Mapping Project (CCAMP) visit: www.r9coastal.org
Contact:KathySchaeferFEMA Study [email protected]
Role Name Phone Number E-mail
FEMA Study Manager KathySchaefer (510)627-7129 [email protected]
Study Project Manager KrisMay (510)622-6640 [email protected]
North Bay Technical Lead Brad Hall (916)371-7400 [email protected]
Central Bay Technical Lead KristaConner (215)446-5190 [email protected]
South Bay Technical Lead Darryl Hatheway (619)905-9488 [email protected]
Outreach Coordinators Wendy Chang (510)844-0576 [email protected]
Lisa Messano (510)879-0911 [email protected]
GISManager James Johnston (510)879-4539 [email protected]
