The Coastal Storm Modeling System (CoSMoS)

Posted on: 9/09/2020 - Updated on: 8/03/2022

Posted by

Kathryn Braddock


The Coastal Storm Modeling System (CoSMoS) makes detailed predictions of storm-induced coastal flooding, erosion, and cliff failures over large geographic scales. 

The Coastal Storm Modeling System (CoSMoS) is a dynamic modeling approach that has been developed by the United States Geological Survey in order to allow more detailed predictions of coastal flooding due to both future sea-level rise and storms integrated with long-term coastal evolution (i.e., beach changes and cliff/bluff retreat) over large geographic areas (100s of kilometers). CoSMoS models all the relevant physics of a coastal storm (e.g.,tides, waves, and storm surge), which are then scaled down to local flood projections for use in community-level coastal planning and decision-making. Rather than relying on historic storm records, CoSMoS uses wind and pressure from global climate models to project coastal storms under changing climatic conditions during the 21st century. 

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 6.6 feet), along with an extreme 5-meter (16-foot) scenario. This allows users to manage and meet their own planning horizons and specify degrees of risk tolerance. CoSMoS projections are currently available for the north-central coast (Half Moon Bay to Pt. Arena)San Francisco Baysouthern California, and the central California coast

All modeling results are available as GIS shapefiles, with accompanying metadata, at USGS ScienceBase-Catalog. CoSMoS information can also be accessed, viewed, and downloaded through the Our Coast, Our Future (OCOF) flood mapper, which provides a user-friendly web-based tool for viewing all model results. OCOF also provides resources and guidance for helping communities navigate and utilize the wealth of information provided by CoSMoS.

Although the CoSMoS modeling system was initially developed for use in the high wave-energy environment of the U.S. west coast, CoSMoS is not site-specific and can be utilized on sandy and/or cliff-backed coasts throughout the world.


CoSMoS was developed for hindcast studies, operational applications and future climate scenarios to provide emergency responders and coastal planners with critical storm-hazards information that can be used to increase public safety, mitigate physical damages, and more effectively manage and allocate resources within complex coastal settings.


Managing Organizations

The USGS is a science organization that provides impartial information on the health of our ecosystems and environment, the natural hazards that threaten us, the natural resources we rely on, the impacts of climate and land-use change, and the core science systems that help us provide timely, relevant, and useable information.