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RESEARCH PRODUCT

Uncertainties in shoreline position analysis: the role of run-up and tide in a gentle slope beach

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Abstract. In the last decades in the Mediterranean sea, high anthropic pressure from increasing economic and touristic development has affected several coastal areas. Today the erosion phenomena threaten human activities and existing structures, and interdisciplinary studies are needed to better understand actual coastal dynamics. Beach evolution analysis can be conducted using GIS methodologies, such as the well-known Digital Shoreline Analysis System (DSAS), in which error assessment based on shoreline positioning plays a significant role. In this study, we propose a new approach to estimate the positioning errors due to tide and wave run-up influence. To improve the assessment of the wave run-up uncertainty, we used a spectral numerical model to propagate waves from deep to intermediate water and a Boussinesq-type model for intermediate water up to the swash zone. Tide effects on the uncertainty of shoreline position were evaluated using data collected by a near tide gauge. The proposed methodology was applied to an unprotected, dissipative Sicilian beach far from harbours and subjected to intense human activities over the last 20 years. The results show wave run-up and tide errors ranging from 0.12 m to 4.5 m and from 1.20 m to 1.39 m, respectively.