Interaction of river discharge and salty water intrusion near a river mouth under hurricane wind forcing

Hurricane induced inundation and penetration near and into river mouth are a function of the height and duration of the surge, river discharge, the slope of the land, and other terrain features. Numerical study of the interaction of storm induced surge, inundation, and river discharge around river mouth area is a complicated hydrodynamic process. In this paper, a three dimensional baroclinic finite volume numerical model is employed to investigate the two-way interaction of seaward moving river discharge and landward intrusion of salty water. The hindcast of Hurricane Isabel (2003) shows that the contribution of freshwater discharge to inundation near Tar-Pamlico River mouth is about 15% of the total flooding along the western coast of Pamlico Sound. Salty water intrusion can reach 100km upstream from the river mouth. The interaction of river discharge and salty water intrusion and its effect on coastal inundation may be more severe for higher category hurricanes with more water discharges.