Photo credit: Kevin Long

USGS Coastal Storm Modeling System (CoSMoS)

CoSMoS is the only modeling tool that makes coupled storm and sea level projections widely and freely available. Its use of future climate projections scaled down to predict local coastal hazards makes the results directly applicable for localized planning and preparedness.

Background: What is CoSMoS & Who Should Use It?

The Coastal Storm Modeling System (CoSMoS) is a tool developed by the United States Geological Survey (USGS) in partnership with Deltares that predicts the combined impacts of coastal storms, sea level rise, and river flooding at the local scale. Planners, managers and residents can use products from the new system to help understand the exposure risk from  coastal hazards (surface flooding, rising groundwater, and coastal erosion) to people, infrastructure, and resources. 

Washington coasts are home to diverse communities, important infrastructure and industry, and habitat critical for commercial fisheries, Tribal Treaty Rights, and public well-being. Much of this coastline is at risk of flooding due to the combined effects of sea level rise, storms, tides, and overflowing rivers. Each piece of shoreline has unique characteristics that determine how coastal flooding will affect it, and CoSMoS has several key features that make it especially useful for this type of problem. First, it uses wind, atmospheric pressure, and sea surface temperature data from Global Climate Models. It then combines these data with models of regional and local water levels that include factors like tides and storm surge. Finally, it incorporates a wide range of sea level rise scenarios, allowing planners to view potential flooding impacts in both the near and long term. The results are unique in simulating decades of time and are able to capture climate variability important to defining recurrence of extreme water levels everywhere. In the past, this type of information was only available via a few tide gage stations, often located in protected harbors. 

Predicting local flooding impacts with this level of precision and resolution (at the 1m scale) has many uses, especially to local planners. Data such as those from CoSMoS help planners determine which assets – from roads to ports and parks – are most at risk, so that communities can plan for and prioritize adaptation actions. CoSMoS has also been combined with other information to show local socioeconomic impacts from different flooding events via the USGS Hazard Exposure Reporting and Analytics web tool. With hazard and exposure risk information in hand, planners can begin to determine which mitigation and adaptation strategies will work best for their communities. 

CoSMoS Availability in Washington

There are three CoSMoS products: overland flooding, groundwater and shoreline change. A helpful image is provided below to show the expected delivery dates of each product. Overland Flooding products are already available for Whatcom County. King and Pierce County can expect flooding products to be available mid 2025. Flooding products for other Salish Sea and Pacific Coast locations are estimated to be available between 2026-2027. Groundwater products are currently available for all of Puget Sound, and expected to be available to the Pacific Coast by end of 2025. Shoreline Change products will be made available to the Pacific Coast only, and is expected by the end of 2026. 

Whatcom County is the first in Washington state to receive specific flood projections and results from the tool. To learn more about how Whatcom County used the data in their Compound Flood Vulnerability Assessment, view their StoryMap here. 

Where Can I Access CoSMoS Data?

Products are available to view in the USGS Hazard Reporting Exposure and Analytics web tool and for download of geospatial hazard data:

Flooding (Whatcom County)

Grossman, E.E., vanArendonk, N.R., Crosby, S.C., Tehranirad, B., Nederhoff, K., Parker, K.A., Barnard, P.L., Erikson, L.H., Danielson, J.J. 2024. Coastal hazards assessment associated with sea level rise and storms along the Whatcom County, Northwest Washington State coast, U.S. Geological Survey data release, https://doi.org/10.5066/P9I08NS5.

Groundwater (Puget Sound)

Befus, K.M., Hoover, D.J., Grossman, E.E., and Barnard, P.L., 2024, Future coastal groundwater hazards in the Puget Sound region, Washington, U.S.A.: U.S. Geological Survey data release, https://doi.org/10.5066/P946YX5G.

Recent Trainings and Webinars on CoSMoS Products

The Shoreline and Coastal Planners Group held two sessions of a Coastal Groundwater Hazards webinar, which provided an overview of the USGS Coastal Storm Modeling System (CoSMoS) groundwater hazard products currently available for all Puget Sound counties. The recorded webinar also featured a case study of how CoSMoS groundwater products have been used in California, a live demonstration of the groundwater tools in HERA, and breakout rooms for a hands-on practice session.

Chris Elder (Whatcom County Public Works Department) and Kurt Baumgarten (Port of Bellingham) gave a Lunch & Learn on the Whatcom County Compound Flood Vulnerability Assessment. This webinar covers how CoSMoS data was used in the assessment and how they plan to use it in Phase 2 of their adaptation planning. Watch the recording of this presentation here.

CoSMoS team

USGS

Maya Hayden

Eric Grossman

Bill Labiosa

Patrick Barnard

Kai Parker

 

WSG

Chandler Countryman

Sydney Fishman

Ian Miller

Bridget Trosin

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CoSMoS for Washington state is an expansion of work that began on the California coast. Headed by the United States Geological Survey (USGS), the Washington CoSMoS expansion is the result of a years long partnership with the Washington Coastal Hazards Resilience Network, United States Environmental Protection Agency, the Washington state Department of Ecology, University of Washington Climate Impacts Group, Washington Sea Grant, Deltares, Western Washington University, and Northwest Indian Fisheries Commission.

Contact

Have a question or need technical assistance? You can send inquiries directly to Chandler Countryman (Washington Sea Grant CoSMoS Team, ccount@uw.edu).

Additional CoSMoS Resources

WA-relevant publications:

  • Grossman, E.E.; Tehranirad, B.; Nederhoff, C.M.; Crosby, S.C.; Stevens, A.W.; Van Arendonk, N.R.; Nowacki, D.J.; Erikson, L.H.; Barnard, P.L. Modeling Extreme Water Levels in the Salish Sea: The Importance of Including Remote Sea Level Anomalies for Application in Hydrodynamic Simulations. Water 2023, 15, 4167. https://doi.org/10.3390/w15234167
  • Crosby SC, Nederhoff CM, VanArendonk N, Grossman EE. Efficient modeling of wave generation and propagation in a semi-enclosed estuary. Ocean Modelling. 2023. https://doi.org/10.1016/j.ocemod.2023.102231
  • Nederhoff, K.; Crosby, S.C.; Van Arendonk, N.R.; Grossman, E.E.; Tehranirad, B.; Leijnse, T.; Klessens, W.; Barnard, P.L. Dynamic Modeling of Coastal Compound Flooding Hazards Due to Tides, Extratropical Storms, Waves, and Sea-Level Rise: A Case Study in the Salish Sea, Washington (USA). Water 2024, 16, 346. https://doi.org/10.3390/w16020346.

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