Effect of Local Winds on Salinity Intrusion in the Columbia River Estuary

Abstract

In the highly energetic Columbia River estuary, river discharge and tides are known as dominant factors controlling circulation. In this study, the 3D hydrodynamic unstructured-grid model SELFE is used to investigate the influence of the local wind on salinity intrusion. Numerical simulations are carried out for realistic conditions for the year 2014, with 4 km and 32 km resolution atmospheric forcing. The effect of the wind is further investigated by switching it off in the estuary. Analysis of modeled salinity intrusion length shows that the resolution of atmospheric forcing matters, and strong episodic winds occurring in winter and fall exert some control on this parameter. Energetic easterly winds tend to increase salinity intrusion length, while energetic westerly winds tend to do the reverse. Results also suggest that energetic winds can differentially alter salt intrusion in the two main channels—the north and south channels—of the estuary. These findings offer motivation for future studies to better understand these processes.