Tidal fronts in estuaries

Abstract

Three estuaries in Wales were carefu\ly surveyed during fü)()d conditions. They are characterized by the intrusion of a tidal front. In one estuary the front retreats afrer maximum flood velocities and stratification persists during the wholc tidal cycle. In the other estuaries the flood erases the initial stratification causing partially or totally mixed situations, A tidal Fraude number is employed to characterize the cvolution of stratification during the flood. I t is shown that gravity current theory approximately holds under wel!-stratified conditions in a region near to, but not too clase to, the head of the front.