Water-level forecasting for the Bay

Hydro-CoSMoS links watershed and coastal models in a water-level forecast prototype for San Francisco Bay. Its coastal side runs on the Delft3D Flexible Mesh San Francisco Bay and Delta model.

Partners: U.S. Geological Survey, NOAA (Physical Sciences Laboratory, Global Systems Laboratory and National Weather Service), California Department of Water Resources, Deltares USA

All case studies

Hydro-CoSMoS, a coupled river and coastal forecast prototype for San Francisco Bay

Flooding along the Bay shoreline and in tributaries such as the Napa River depends on tides, storm surge and river flow acting together. Hydro-CoSMoS is a forecast prototype that links watershed and coastal models for San Francisco Bay. Its coastal side builds on the USGS Coastal Storm Modeling System and the Delft3D Flexible Mesh San Francisco Bay and Delta model. The 2018 NOAA summary report describes the project, whose prototype focused on the Napa River and San Pablo Bay.

Herdman and colleagues used Delft3D-FM to simulate storms on a realistic and an idealized Napa River. The highest water levels occurred when high tides, storm surge and large river discharge coincided. Large tidal amplitudes reduced the upstream travel of storm surge, and the timing between peak discharge and high tide controlled where the highest levels occurred. Tehranirad and colleagues then hindcast the February 2019 storm with and without real-time river discharge, and tested remote non-tidal residuals taken from a global ocean model. Accurate forecasts of both inputs improved the prediction of extreme water levels in the Bay.

In the 2021 assessment, emergency managers took part in a tabletop exercise that tested the forecast information products. Their feedback guided which model outputs and formats to develop next. In 2021, NOAA reported that Hydro-CoSMoS was being used in the Advanced Quantitative Precipitation Information (AQPI) project, a federal, state and local partnership in the Bay Area.

Downloads

Report: Kim, J., Johnson, L. E., Cifelli, R., et al. (2018). San Francisco Bay integrated flood forecasting project summary report. NOAA Technical Memorandum OAR PSD-317.
Paper: Herdman, L., Erikson, L., and Barnard, P. (2018). Storm surge propagation and flooding in small tidal rivers during events of mixed coastal and fluvial influence. Journal of Marine Science and Engineering, 6(4), 158.
Paper: Tehranirad, B., Herdman, L., Nederhoff, K., et al. (2020). Effect of fluvial discharges and remote non-tidal residuals on compound flood forecasting in San Francisco Bay. Water, 12(9), 2481.
Paper: Cifelli, R., Johnson, L. E., Kim, J., et al. (2021). Assessment of flood forecast products for a coupled tributary-coastal model. Water, 13(3), 312.