K2 tidal constituents. Overall the percent errors in amplitudes range between 3.1
and 16.1 percent, the phase differences range between 2.0 and 6.2 deg.
Differences in values of tidal data between the NOS and IHO/NOAA data-
bases can be explained by the constantly shifting bathymetry of coastal regions
and of the geometry of the coasts themselves as well as by the occurrences of
nontidal events. Over the course of a few years, the geometry and bathymetry of
an estuary can change dramatically due to the natural transport of sediments or
through dredging operations, thus altering the hydrodynamics of the flow in the
area. If an elevation recording station is located in an area where the localized
geography is in a perpetual state of change, there may be differences in measured
harmonic values depending on when the information was collected. Nontidal
events including wind-driven events, such as hurricanes and tropical storms,
radiational heating cycles of the surface waters, and other natural disturbances
can also perturb observed tidal constituent values from analysis to analysis. The
simple intercomparison of the constituent data is only an estimate of the long-
term reliability of this data. It is also related to the reliability of shoreline and
near coastline bathymetric values. However, these estimates of measurement
error for each constituent should be taken into consideration when comparing
simulated results to the available measured data.
16
Chapter 4 Description and Error Analysis of Field Data