Coastal Flooding Hazard in Low-Tide and High-Tide Coasts: Evidence from the North Aegean Coast

Abstract

Based on the analysis of high quality tide gauge data, for the first time available, we have analyzed the relationship between astronomic and meteorological tide in the harbor of Alexandroupolis, in the northern coast of the Aegean; in this area the tide takes the max value for the whole region, but is still small (<10–20 cm). Our analysis was based on a step-by-step geodetic approach, and not an automatic procedure which may miscalculate the periodic components in short-period records. A further comparison of these data with data from other coasts with high tide (several meters) revealed that the amplitude of common surges in the Aegean is high, occasionally of the amplitude of extreme surges recorded in other regions, but the risk of flooding much higher. The ratio of the meteorological versus the astronomic tide in the Aegean is high, of the order of 40 over relatively long periods, about one or two orders of magnitude higher than in high-tide coasts. For this reason intervals with surges leading to flooding are limited to a few hours per day along high-tide coasts (during the high peaks of the astronomical tide), while in low-tide coasts such as the Aegean, in which the total tide is controlled by surges, the risk of flooding is high 24 h/day.