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Helping Communities Understand Future Coastal Hazards

The USGS Coastal Processes Team has developed the Coastal Storm Modeling System (CoSMoS) to help residents of coastal California understand their vulnerabilities from storms and sea-level rise.

This article is part of the January-February 2017 issue of the Sound Waves newsletter.

With the stunning beauty of our coastline throughout the United States and its territories, it is no surprise that many people want to live along the coast. This coastal living, however, comes with vulnerability to impacts from natural hazards, such as hurricanes, winter storms, tsunamis, and erosion of beaches and coastal cliffs. Climate change will intensify these hazards. Even today, many coastal communities along the east coast are experiencing increased nuisance flooding—also referred to as sunny-day flooding—in which streets and infrastructure flood simply because of high tides or windy days. This flooding has been exacerbated in recent decades by sea-level rise. U.S. coastal communities look to expertise from the USGS to provide cutting-edge projections of natural-hazard impacts today and into the future.

Computer screen shots side by side showing 3 future projections for Stinson Beach California with varying sea level rise
Examples of projections from the Our Coast, Our Future (OCOF) viewer for Stinson Beach in San Francisco, California, for daily conditions for October 31, 2016 (left), daily conditions plus 50 centimeters (20 inches) of sea level rise-expected by about mid-century (center), and a 100-year (or 1 percent) storm with 50 centimeters (20 inches) of sea-level rise (right). These projections demonstrate how neglecting to plan for storm impacts could lead to a substantial underestimation of risk along the coast. Image credits: OCOF, CoSMoS Model Results Product Suite. Image credit: USGS.

On the west coast of the United States, the USGS Pacific Coastal and Marine Science Center’s Coastal Processes Team, led by Patrick Barnard and a group of 10 modelers, geologists, engineers, and oceanographers, has developed the Coastal Storm Modeling System (CoSMoS) to help the 20 million residents of California coastal communities understand their vulnerabilities from storms and sea-level rise. CoSMoS is a state-of-the-art modeling system that models all the relevant physics of a coastal storm (for example, tides, waves, and storm surge), which are then scaled down to local flood projections. Rather than relying on historic storm records, CoSMoS uses wind and pressure from global climate models to project coastal storms under changing climatic conditions. Projections of multiple storm scenarios (daily conditions, annual storm, 20-year- and 100-year-return intervals) are provided under a suite of sea-level rise scenarios ranging from 0 to 2 meters (0 to 6 feet), along with a catastrophic 5-meter (16-foot) scenario. This allows users to manage and meet their own planning horizons and specify degrees of risk tolerance.

To ensure that the modeling results meet the needs of the coastal communities it serves, the USGS has been working with a diverse group of partners and stakeholders to support the development of climate-change-impact plans through the Our Coast, Our Future (OCOF) program. The OCOF is a partnership among the USGS, Point Blue Conservation Science, Greater Farallones National Marine Sanctuary, NOAA’s Office for Coastal Management, National Estuarine Research Reserve System, Bay Area Ecosystems Climate Change Consortium, the National Park Service, and Ecosystem-Based Management Tools Network. By working closely with Point Blue Conservation Science to develop the OCOF web site and flood map, the USGS is delivering tools and information that can inform California coastal communities about managing coastal flooding risks across the California coast. The OCOF web resources provide a user-friendly format in which coastal professionals and stakeholders can access and use information from the CoSMoS model for short- and long-term climate-change planning.

To date, OCOF has directly served 14 San Francisco Bay Area communities/counties by supporting climate-adaptation planning projects. Both CoSMoS and OCOF are recognized as leading tools and sources of information for short- and long-term planning by California State agencies, such as the California State Coastal Conservancy, California Coastal Commission, California Department of Transportation, and California’s Office of Emergency Services. The CoSMoS results are also being used by researchers at the University of California, Berkeley and other local universities to identify vulnerability at finer scales for use by planners, emergency personnel, and natural-resource managers.

Earlier this year, the CoSMoS team was honored with the 2016 Point Blue Outstanding Partner Award. Accepting on behalf of the CoSMoS team, Barnard noted, “Working with Point Blue and all of our partners throughout the S.F. Bay Area has helped our group better understand what kind of information coastal communities need to prepare for natural hazards today and with climate change. We are honored to have received this tremendous accolade from Point Blue Conservation Science.”

In 2014, the CoSMoS team began developing projections for southern California, from Santa Barbara to the United States/Mexico border. Results from this modeling were released in fall 2016. Following the OCOF example from northern California, the CoSMoS team has established partners throughout southern California, such as the University of Southern California’s (USC) Sea Grant Program, AdaptLA, and San Diego Regional Climate Collaborative, to engage coastal communities and fine-tune model projections and products to meet their needs. New work along the central coast of California will begin in winter 2017, which will lead to methodologically consistent coverage of nearly all the California coastline.

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