EQUILIBRIUM FLOW AREAS OF TIDAL INLETS ON SANDY COASTS

The flow area of inlets on sandy coasts is a unique function of the tidal prism when equilibrium has been achieved. The size of material, the presence or absence of jetties, and the magnitude of general littoral drift does not appear to affect this equilibrium flow area within the accuracy of the data available. In the summer of 1929, the writer made a reconnaissance of the beaches and harbors of the Pacific Coast of the United States for the predecessor organization of the U. S. Beach Erosion Board. In tiie years preceding this study, many tidal inlets on the Worth Pacific Coast had been improved for navigation by constructing jetties, and the progress of these inlets towards stabilization was being followed through frequent hydrographic surveys, which were available for study. The obvious fact that large inlets were found at large bays and small inlets at small bays suggested the possibility that there might be a unique relationship between entrance area and tidal prism.