Note
Tidal and low frequency nontidal exchanges of water between a coastal lagoon and adjacent continental shelf are investigated within the context of flushing, using a computer model based on the continuity equation. Flushing is quantified by the 50% renewal time. The arrival of new ocean water occurs as a result of longitudinal diffusion and a degree of advective transport governed by the flexibility of segment boundaries to move with the ebb and flood of the tide. The model is applied to the Indian River lagoon system, lying along the Atlantic coast of Florida, USA.