The interaction of continuous freshwater flow from an upstream basin into a bar-blocked estuary is investigated following ideas previously proposed by Debler and Imberger. The interface point, defined as the point of confluence between the initial saltwater wedge and the freshwater, is considered to be characteristic of the interaction between the water bodies. The previous semiempirical model of Coates and Guo has been reconsidered on the basis of realistic wedge shapes obtained from physical and numerical experiments. The approach considers conservation and conversion of energies in the dynamic environment. The present approach enabled the writers to obtain a semiempirical model that matches published experimental data fit for the initial phase of the wedge displacement. It is observed that the new model complements the earlier relationship of Coates and Guo for predicting the salt wedge dynamics for the initial phase of the interaction. © 2007 ASCE.