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Since maxima fluctuations within the study period resulted in about m 0.4 m and the average beach slope is 3.59 %
(Figure 3) the shoreline positioning uncertainty due to tide variation is ~ m 10 m.

5. DISCUSSION AND CONCLUSIONS
The proposed methodology, even if in a preliminary phase, allows evaluating tides and waves influence in positioning
the shoreline through remotely sensed images. These are often the only tools available to build-up the morphological
evolution of a beach in the last decades with sufficient accuracy. Shoreline positioning through airborne images are often
affected by uncertainty in the user visual interpretation of the wet/dry boundary of a beach, due to both waves and
images characteristics at the acquisition time. The study case shows that wave motion, together with local sea
characteristics, produces a positioning error of about 15 meters. Shoreline and run-up delimit a zone strictly dependent
on ordinary sea storm, during which they are both submerged and that therefore should be assumed as respect zone and
should undergoes the rules of the maritime State property. Uncertainties due to sea level fluctuation, causing an error of
≈ 10 m, must be superimposed to those caused by the run-up (≈ 7.7 m). Methodology limits are strictly related to
offshore buoy data quality and availability. Run-up has been estimated using an empirical relationship retrieving an
accurate value, even if the implementing of a hydraulic model to verify shoreline position is actually in progress.
However the knowledge of maritime conditions during the remote sensing overpass is fundamental to rigorously verify
the positioning.

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