(1) “Apparent shoreline” means the line drawn on a map or chart in lieu of the mean high-water line or mean low-water line in areas where either or both may be obscured by marsh or mangrove, cypress, or other types of marine vegetation. This line represents the intersection of the mean high-water datum with the outer limits of vegetation and appears to the navigator as the shoreline.

(2) “Comparison of simultaneous observations” means a method of determining mean values by comparison of short-period observations at a station with simultaneous observations made at a station for which mean values, based on long-period observations, are available.

(3) “Control tide station” means a place so designated by the department or the National Ocean Service at which continuous tidal observations have been taken or are to be taken over a minimum of 19 years to obtain basic tidal data for the locality.

(4) “Datum” means a reference point, line, or plane used as a basis for measurements.

(5) “Datum plane” means a surface used as reference from which heights or depths are reckoned. The plane is called a tidal datum when defined by a phase of the tide—for example, high water or low water.

(6) “Demarcation” means the act of setting and marking limits or boundaries on the ground.

(7) “Department” means the Department of Environmental Protection.

(8) “Diurnal tides” means tides having a period or cycle of approximately one tidal day.

(9) “Foreshore” means the strip of land between the mean high-water and mean low-water lines that is alternately covered and uncovered by the flow of the tide.

(10) “Geodetic bench mark” means a permanently monumented and precisely referenced and described mark, usually a bronze tablet or copper or bronze bolt leaded or cemented into a masonry structure, which is established to give a definite high point on the monument to which geodetic elevations are referred.

(11) “Interpolated water elevation” means a point between two adjacent tide stations where the water elevation has been determined by interpolation from established datums at the two tide stations.

(12) “Leveling” means the operation of determining differences of elevation between points on the surface of the earth or of determining the elevations of points relative to some arbitrary or natural level surface called a datum.

(13) “Local tidal datum” means the datum established for a specific tide station through use of tidal observations made at that station.

(14) “Mean high water” means the average height of the high waters over a 19-year period. For shorter periods of observation, “mean high water” means the average height of the high waters after corrections are applied to eliminate known variations and to reduce the result to the equivalent of a mean 19-year value.

(15) “Mean high-water line” means the intersection of the tidal plane of mean high water with the shore.

(16) “Mean low water” means the average height of the low waters over a 19-year period. For shorter periods of observation, “mean low water” means the average height of low waters after corrections are applied to eliminate known variations and to reduce the result to the equivalent of mean 19-year value.

(17) “Mean low-water line” means the intersection of the tidal plane of mean low water with the shore.

(18) “Mean range difference” means the variation of the mean range of the tide at two different tide stations.

(19) “Mixed tide” means the type of tide in which the presence of a diurnal wave is conspicuous by a large inequality in either the high or low water heights, with two high waters and two low waters usually occurring each tidal day. The name is usually applied to the tides intermediate to those predominantly diurnal and those predominantly semidiurnal.

(20) “National map accuracy standards” means a set of guidelines published by the Office of Management and Budget of the United States, to which maps produced by the United States Government usually adhere.

(21) “Nineteen-year tidal cycle” means the period of time generally reckoned as constituting a full tidal cycle.

(22) “Nonperiodic forces” means those forces that occur without regard to a fixed cycle.

(23) “Photogrammetry” means the science of making precise measurements from photographs.

(24) “Semidiurnal tides” means tides having a period of approximately one-half of a tidal day.

(25) “Tidal bench mark” means a standard disk or other acceptable fixed point in the general vicinity of a tide station, used for the purpose of preserving tidal information, to which the tide staff at the tide station and the tidal datums determined from the observations at the tide station are originally referred.

(26) “Tidal datum” means a plane of reference for elevations determined from the rise and fall of the tides.

(27) “Tidal day” means the time of the rotation of the earth with respect to the moon, or the interval between two successive upper transits of the moon over the meridian of a place.

(28) “Tide” means the periodic rising and falling of the waters of the earth that result from the gravitational attraction of the moon and the sun acting upon the rotating earth.

(29) “Tide station” means a place at which continuous tide observations have been taken or are to be taken to obtain tidal data for the locality.

(30) “Time difference” means the variation in time between the occurrences of the same phase of the tide at two tide stations.

History.—s. 3, ch. 74-56; s. 3, ch. 91-56; s. 35, ch. 94-356; s. 15, ch. 98-20.