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established, and what they represent. The 1988, p. 470). Hence, exclusion of inlets first part of this work, therefore, discusses might be an oversight, particularly in view of the history of tidal datums determination and the current inlet management effort definition in U. S. coastal waters. undertaken by the State. At a most basic level, the classification of inlets is well
Guidance illustrating proper tidal datums known depending upon the effect of applications for coastal scientists and astronomical tides relative to volume of engineers is available for important basic fluvial discharge (e.g., van de Kreeke, 1992). tidal datums applications (e.g., Cole, 1983, In fact, for many inlets, selection of the 1991, 1997; Pugh, 1987; Lyles and others, proper datum plane assists in providing a 1988; Brown and others, 1995; Gorman and least equivocal representative design water others, 1998; Stumpf and Haines, 1998). reference level. Hence, a section on inlets For other specific cases it is absent. Verbal as they relate to astronomical tides in Florida communications by a few professionals is herein developed. reach only a small audience. Even then, the
latter often results in a blank stare, leaving WATER LEVEL DATUM PLANES the instructor with the message that the
explanation was not comprehended by the In endeavors concerning hydraulic informant, that he or she has predetermined phenomena with a free fluid surface, many that it is not important, or that the informant practitioners have lost perspective in selection has already predetermined just what is of the reference fluid plane across which force proper. The author has, therefore, in the elements propagate, in both the prototypical latter portion of this work presented a series setting and the natural environment. Given of selected examples and discussion about this assertion, perhaps it would be appropriate tidal datums applications. At the outset, one to review the basics of historical development needs to understand that the surveying of tidal datum plane quantification that has profession, in large part, is concerned with withstood the practicable tests of time. the management of error and variability
associated with horizontal and vertical The first recorded effort of geodetic control. It is often the case that one is not leveling in the United States began in 1856convinced by simple directive that there is a 57. During ensuing years surveying control proper methodology, so evidenced by recent become better. As chronicled by Schomaker improper uses of datum applications in (1981), by the first quarter of this century: coastal engineering works cited above. This
occurs because there isnothing to convince After the previous period of one that the methodology is better or best at comparatively short intervals between reducing error or variability. Therefore, the adjustments, 17 years elapsed before author has opted to present a series of the network was adjusted again. In the common improper tidal datums applications meantime, it had become more and to demonstrate, relative to the proper extensive and complex, and included many more sea-level connections. The
application, just why, numerically, they areGeneral Adjustment of 1929 General Adjustment of 1929
inappropriate. incorporated 75,159 km of leveling in the United States and, for the first time,
INLETS/OUTLE AND 31,565 km of leveling in Canada. The
THE ASTRONOMICAL T77DE U.S. and Canadian networks were connected by 24 ties between Calais,
The preceding definition of open ocean Me./Brunswick, New Brunswick; and tides excludes the influence of inlets (perhaps Blaine Wash./ Colebrook, British more appropriately termed outlets after Carter, Columbia. A fixed elevation of zero
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