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Pacific Coastal and Marine Science Center

Coastal Processes

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Location map of San Francisco Bay work.

Above: San Francisco Bay study area

Above: Animation of modeled South San Francisco Bay water level during an extreme high-tide event (king tide). m, meters; MSL, mean sea level. [Read disclaimer.]

CoSMoS 2.1: San Francisco Bay

With primary support from the National Estuarine Research Reserve (NERR), CoSMoS is set-up within the San Francisco Bay as part of Our Coast, Our Future (OCOF).  San Francisco Bay is geographically and bathymetrically complex, necessitating many alterations to the methods used on Northern California’s outer coast.

Scenarios within San Francisco Bay are consistent with the full spectrum of SLR (0 to 2 meters, 5 meters) and storms (daily to 100-year return) used on the outer coast. However, storms events used inside the Bay were derived from numerically modeled wind-wave heights driven by down-scaled wind projections derived from one GCM (Geophsyical Fluid Dynamics Laboratory [GFDL] Earth System Model [ESM] 2M).

Changes from CoSMoS 2.0 for implementation within San Francisco Bay include:

  • Projected freshwater storm-related discharges for Sacramento-San Joaquin Delta and principal tributaries through 21st century included in model simulations
  • In-bay wind waves generated from high-resolution downscaled Global Climate Model (GCM) data
  • Including the effect of ocean swell penetration in the Central Bay
  • Robust flooding uncertainty determined as part of the product suite; incorporates vertical land motion (lift/subsidence), marsh accretion/erosion, flood model uncertainty, vegetation-related LiDAR error, and digital elevation model (DEM) uncertainty

Collaborative Studies

The results are being directly used in climate change vulnerability studies for Marin County and San Mateo County. Projections from CoSMoS 2.1 are being used in follow-on collaborative USGS studies investigating socio-economic climate impacts and vulnerability throughout the Bay. Results from these analyses should be available by the end of 2015.


  • Bay Area Ecosystems Climate Change Consortium
  • Coravai
  • NOAA Coastal Services Center
  • Gulf of the Farallones National Marine Sanctuary
  • National Park Service
  • Point Blue Conservation Science
  • San Francisco Bay National Estuarine Research Reserve (NERR)
  • USGS Earth Resources Observation and Science (EROS) Data Center
Graphic showing extreme winds direction.

Above: Direction of extreme winds (black arrows, wind speed greater than 24 meters/second [m/s]) that produce maximum locally generated waves throughout San Francisco Bay (color shading). h, wave height. [See a larger version; and read disclaimer.]


Inundated areas shown should not be used for navigation, regulatory, permitting, or other legal purposes. The U.S. Geological Survey provides these data “as is” for a quick reference, emergency planning tool but assumes no legal liability or responsibility resulting from the use of this information.

The suggestions and illustrations included in these images are intended to improve coastal-flood awareness and preparedness; however, they do not guarantee the safety of an individual or structure. The contributors and sponsors of this product do not assume liability for any injury, death, property damage, or other effects of coastal flooding.

Use of trade names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey.


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