CoSMoS 2.0: North-central California (outer coast)

CoSMoS Northern California study area

Our Coast Our Future (OCOF) is a collaborative, user-driven project providing science-based decision-support tools to help coastal planners and emergency responders understand, visualize, and anticipate local impacts from sea-level rise (SLR) and storms in the San Francisco Bay region. As part of OCOF, CoSMoS produced a suite of coastal flooding projections for over 40 combinations of anticipated SLR and storm conditions from Bodega Bay south to Half Moon Bay; results are accessible via interactive maps overlaying infrastructure and ecosystem vulnerabilities.

Animation depicting 2-D modeled water level (blue line) and shoreline change (solid line, original beach profile in dashed line) through one tidal cycle along a beach profile near Stinson Beach, California, during a 20-year storm event with projected 1-meter of sea-level rise. Significant wave height (red) at the seaward end of the profile is shown in the upper panel.

Scenarios developed for OCOF feature the full spectrum of SLR (0 to 2 meters, 5 meters) and coastal storms (daily to 100-year return) to meet every possible management planning horizon and degree of risk. The daily, 1-, 20-, and 100-year storm events used in this work were derived from numerically modeled wave heights offshore of San Francisco that were driven by 21st century wind projections derived from an ensemble of the latest Global Climate Models (GCMs) developed for the 5th Assessment Report of the Intergovernmental Panel on Climate Change. Those offshore wave conditions, combined with tides and storm surge, are modeled down to the local level using state-of-the-art numerical modeling tools to determine coastal water levels, which are then projected onto a 2-meter Digital Elevation Model (DEM) to estimate the extent of flooding.

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.

Screenshot of Our Coast, Our Future (OCOF) interactive map view of Stinson Beach, California, showing extent of flooding predicted if subjected to a sea-level rise of 100 centimeters (about 40 inches) and elevated water levels caused by a 100-year storm.

Approach used in identifying future coastal flooding risk with CoSMoS. Output from relevant Global Climate Models (GCMs) is used to generate global/regional swell and waves; results are scaled down to regional and sub-regional levels using a suite of models accounting for tides, atmospheric pressure, and wind; these fine-scale results are translated as relevant hazards projections at the parcel scale, including flooding, wave heights, coastal erosion, and cliff failures.