Characteristics and Behavior of Pacific Cost Tidal Inlets

All generally available navigation charts and tidal data were critically examined for 48 tidal inlets, lagoon, and bays along the coasts of California, Oregon, and Washington to determine the tidal prism and throat area of the inlets. Twenty-five of the inlets yielded data which were considered reliable, and a relationship between tidal prism and inlet area was formulated. All 25 inlets, except one, were originally in erodible material although in numerous instances the inlets now have been stabilized by jetties. Some inlets depart radically from a fairly good relationship between tidal prism and throat area for most inlets. The probable reason for this departure is examined. Whether or not an inlet is always open, always closed, or open on occasions, appears to be related to the ratio of wave power to tidal power. An approximate closure criterion is presented from an analysis which considered 46 of the inlets.