PNNL

Abstract

This paper presents a modeling assessment of storm surge in the Salish Sea—a large and complex estuarine system on the Pacific Northwest that is under the threat of extratropical cyclones. A method was developed to systematically identify storm surge events in the Salish Sea based on water level records at four representative tidal gauges in the Salish Sea. The maximum storm surge distribution in the Salish Sea was predicted using ensemble simulations of 34 major historical storm events from 1980 to 2016. The model predictions were validated by field observations of water level and velocity using a suite of model performance metrics. Model results suggest that the maximum storm surge in the Salish Sea is generally in the range of 0.8 m to 1.03 m and is highly heterogeneous in space. The model results also shows that a strong north-south gradient with higher surge height occurring in the north, and is primarily caused by the southerly wind in winter months. The sensitivity analysis with wind forcing suggested that storm surge in the Salish Sea is dominated by the remote surge from the Pacific Ocean, and the local wind contributes up to approximately 20% of the surge variability. As the first systematic modeling study of storm surge in the Salish Sea, this paper elucidates storm surge characteristics and risk in this largest inland sea system in the world.