Background: What is CoSMoS and 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. 

History: Where Did CoSMoS Originate?

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