A Medium-Term Study of Molise Coast Evolution Based on the One-Line Equation and “Equivalent Wave” Concept

Abstract

The Molise region (southern Italy) fronts the Adriatic Sea for nearly 36 km and has been suffering from erosion since the mid-20th century. In this article, an in-depth analysis has been conducted in the time-frame 2004–2016, with the purpose of discussing the most recent shoreline evolution trends and individuating the climate forcings that best correlate with them. The results of the study show that an intense erosion process took place between 2011 and 2016, both at the northern and southern parts of the coast. This shoreline retreat is at a large extent a downdrift effect of hard protection systems. Both the direct observation of the coast and numerical simulations, performed with the software GENESIS, indicate that the shoreline response is significantly influenced by wave attacks from approximately 10° N; however, the bimodality that characterizes the Molise coast wave climate may have played an important role in the beach dynamics, especially where structural systems alternate to unprotected shore segments.

Predicting Crenulate Bay Profiles from Wave Fronts: Numerical Experiments and Empirical Formulae

“…In order to follow the method used in the numerical trial, the bay has been modelled in such a way that wave fronts could extend leeward the headland without any interference: the real bathymetry of the area has been employed until the diffraction point location, where the water depth is about 3 m, then a gentle slope of 1:100 has been adopted; the coastline has been shifted and cut landward and a sponge layer has been used, in order to avoid reflection phenomenon (Figure 17). Numerical simulations have been performed wave detecting the equivalent direction of 205 • N, since it is representative of the effects of the entire wave climate on long-shore sediment transport [41]. As concerns wave period, the average measured omni-directional peak period (5.9 s) has been investigated.…”

Trigno River Mouth Evolution via Littoral Drift Rose

“…assuming that the "true" shoreline position remains unvaried in the interval 𝑡 − 𝑡 . Therefore, vLIM is reasonably equated to vE95, and the vLIM value detected by [10] for the 2004-2016 time interval was equal to 0.37 m/year, which represents the expected error given by the shoreline surveys.…”

“…A remarkable analysis of Molise coastline evolution has been extensively performed in the last decades. More recently, [10] analyzed the average rate of shoreline change of the entire Molise coast within the reference time interval 2004-2016, using the linear regression rate (LRR) as an indicator. The 2004-2016 shoreline data came from the digitalization in the ArcGis Environment of photograph reliefs from different sources.…”

“…The 2004-2016 shoreline data came from the digitalization in the ArcGis Environment of photograph reliefs from different sources. Specifically, since the digitalization procedure produced a certain degree of uncertainty related to measurement errors of the shorelines, a significance analysis was carried out by [10] for the LRR function of the Molise coast, as briefly summarized below for the sake of clarity.…”

“…Specifically, since the digitalization procedure produced a certain degree of uncertainty related to measurement errors of the shorelines, a significance analysis was carried out by [10] for the LRR function of the Molise coast, as briefly summarized below for the sake of clarity. Treating measurement uncertainties in the frame of the classical theory of errors, the measured shoreline position is seen as the sum of the "true" position plus a random error component, modeled as a Gaussian random variable with zero mean and a standard deviation equal to the root-mean-square (RMS) error [10]. Accordingly, the significant LRR (x) function of the Molise coast was obtained, recognizing areas affected by significant accretion or erosion as those segments of coast where the shoreline change rate exceeds a certain limit value (vLIM) and remains above it for a minimum length, lLIM.…”