Coastal Flooding & Solutions, Workshop Case Studies

Operational total water level forecasts for the U.S. west coast

Project Description

The operational Total Water Level and Coastal Change (TWL&CC) Forecast system provides real-time forecasts of total water levels and probabilities of coastal change along approximately 4,700 km of open, sandy shores on the Atlantic and Gulf Coasts; the system is currently being developed and implemented for the entire west coast, from the U.S./Mexico border to the Canadian border. The forecast system is rooted in a collaboration between the US Geological Survey (USGS) and the National Oceanic and Atmospheric Administration (NOAA). The TWL&CC Forecast Viewer is a web-based platform that provides multi-day forecasts of tides, storm surge, and waves as modeled by NOAA and driven by forecaster-developed winds. Recent advancements include high resolution nearshore wave models capable of resolving complex bathymetries that abut much of the west coast. At the shoreline, modeled wave and wind-driven water levels are combined with information on beach types, elevations, and research products developed by USGS over the past two decades to provide forecasts of total water levels at sandy, cliffed, and hardened coasts. At locales where dunes, cliffs, bluffs, revetments, or other structures exist, the total water levels are compared with elevations of the toe and crest to estimate the probability of wave collision, overwash, and inundation. The TWL&CC forecasts are expected to be available online to the public later this year (2021).

Key Successes

this work is a continuation of work that was initiated on the east coast. The forecasts are used used by National Weather Service (NWS) in their Advanced Weather Interactive Processing System (AWIPS) dashboard, and local emergency planners (e.g., Dare County, NC). Additionally, the TWL&CC model is slated to be used to create hindcast simulations for the Consumer Option for an Alternative System to Allocated Losses (COASTAL) Act, which is a law designed to reduce costs to the National Flood Insurance Program by delineating between wind and water damage for homes destroyed by a tropical cyclone.


missing in-house expertise in fortran coding; lack of data for validation of TWLs

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