The Molise coast extends for 36 km between the mouths of the Formale del Molino channel to the North and of the Saccione Stream to the South. In the last century, the evolution of the Molise coast has been strongly influenced by erosion processes that have caused first the erosion of the Trigno and Biferno River deltas then widespread shoreline retreat. The Molise coast is still suffering erosion, which is actually causing the retreat of several coastal stretches. This phenomenon is most likely to persist even in the future, especially when taking in account current sea level rise scenarios, exposing the economical and touristic activities to serious damages. The aim of this study is therefore to evaluate the erosion risk of the southern portion of the Molise coast, stretching from the Termoli promontory to the Saccione Stream mouth, a coastal zone characterized by intense shoreline evolution. The methodology used for the overall estimation of coastal risk involves the evaluation of two synthetic indexes. The first concerns the evaluation of the susceptibility to erosion (ISE) obtained by the linear correlation of four sub-indexes, which characterize the coastal system in terms of morphologies of beach and dune systems, shoreline evolution and wave climate effect. The second index analyzes the exposure to erosion by means of a method that is based on the assessment of the socio-economic value S (population, degree of urbanization and high ecological value) and potential damage D (in economic terms and in human lives) whose combination leads to the estimation of the exposure value index Ex. Finally, the coastal erosion risk R is evaluated through the matrix product between susceptibility and exposure indexes. Based on obtained R values, the study area is divided into four risk classes. The application of this methodology allowed dividing the southern coast of Molise in 33 sectors with different levels of erosion risk. In detail, 2 km and 6 km of the coastal area refer respectively to very high erosion (R4 class) and high erosion risk (R3 class). They correspond to 15 % and 41 % of the study area, respectively, and are mostly situated south of the Biferno River mouth (Lido di Campomarino) and south of the Campomarino harbor (Nuova Cliternia). These coastal areas have a high socio-economic and environmental value due to the presence of tourist infrastructure (Campomarino Lido) and protected ecological areas (SCI IT7222216 and SCI IT7222217). Their high level of risk, therefore, has a high impact on both human activities and the biodiversity conservation of the dune systems that host protected and endangered species. The results obtained in this study have highlighted the need for an integrated territorial management that takes into account not only individual local needs and urgencies but also the global coastal equilibrium of the Molise coast. In this context, the proper maintenance of coastal defense structures along the littoral and the definition of strategic plans for the defense and recovery of dunes could contribute to an important risk value reduction and to the coastal system resilience increase.

La costa molisana si estende per circa 36 km tra lo sbocco del canale Formale del Molino, a nord, e la foce del Torrente Saccione, a sud. Nel corso dell’ultimo secolo, l’evoluzione di questo tratto di litorale è stata fortemente controllata dall’erosione che ha portato al completo smantellamento dei delta a cuspide dei Fiumi Trigno e Biferno. Ancora oggi questo fenomeno causa un arretramento articolato della linea di riva in diverse aree della costa molisana. È evidente che l’erosione costiera possa perdurare anche in futuro, specie se si tiene conto degli scenari di innalzamento del livello del mare ben noti in letteratura, esponendo le attività economiche e turistiche presenti sul litorale molisano a potenziali gravi danni. A tale scopo, il presente studio si propone di valutare il rischio all’erosione del settore compreso tra il promontorio di Termoli (CB) e il Torrente Saccione, particolarmente sensibile all’arretramento della linea di costa. La metodologia adottata per il calcolo del rischio costiero è basata sulla valutazione di due indici sintetici. Il primo riguarda la stima della suscettibilità all’erosione (ISE) e permette di suddividere la costa analizzata in classi di suscettibilità all’erosione attraverso la correlazione lineare di quattro sub-indici che caratterizzano il sistema costiero in termini di morfologia della spiaggia e del sistema dunale, evoluzione della linea di riva ed effetto del clima ondoso. Il secondo indice analizza i beni potenzialmente esposti all’erosione attraverso la valutazione del valore socio-economico S (popolazione, grado di urbanizzazione e aree ad alto valore ecologico) e del danno potenziale D (in termini economici e di vite umane) la cui combinazione porta alla stima dell’indice del valore esposto Ex. L’indice del rischio all’erosione R è infine valutato attraverso il prodotto matriciale tra l’indice di suscettibilità e l’indice del valore esposto con l’individuazione di quattro diversi livelli di rischio. L’applicazione di questa metodologia ha permesso di suddividere la costa meridionale del Molise in 33 settori a diverso livello di rischio all’erosione. In particolare, nelle classi R4 (rischio molto alto) e R3 (rischio alto) ricadono rispettivamente 2 km e 6 km di costa, corrispondenti al 15% e al 41% dell’area analizzata, localizzati principalmente a sud della foce del Biferno (Lido di Campomarino) e a sud del Porto di Campomarino (Nuova Cliternia). Questi settori costieri sono caratterizzati da un elevato valore socio-economico e ambientale data la presenza di infrastrutture turistiche (Campomarino Lido) e di aree ecologiche protette (SIC IT7222216 e SIC IT7222217). L’alto livello di rischio valutato per questi settori comporta dunque un elevato impatto sia sulle attività antropiche sia sulla conservazione della biodiversità e degli habitat dunali che ospitano diverse specie protette e a rischio estinzione. I risultati ottenuti in questo studio mettono in evidenza la necessità di una gestione integrata del territorio, capace di tener conto non solo delle singole emergenze locali, ma anche dell’equilibrio globale della costa molisana. In questo contesto, la corretta manutenzione delle opere di difesa costiere presenti lungo il litorale e la definizione di piani strategici per la difesa e il recupero delle dune, possono determinare un importante diminuzione del valore di rischio e incrementare la capacità di resilienza dell’intero sistema costiero.

Rischio all’erosione costiera del settore meridionale della costa molisana

Rosskopf C. M.
2017-01-01

Abstract

The Molise coast extends for 36 km between the mouths of the Formale del Molino channel to the North and of the Saccione Stream to the South. In the last century, the evolution of the Molise coast has been strongly influenced by erosion processes that have caused first the erosion of the Trigno and Biferno River deltas then widespread shoreline retreat. The Molise coast is still suffering erosion, which is actually causing the retreat of several coastal stretches. This phenomenon is most likely to persist even in the future, especially when taking in account current sea level rise scenarios, exposing the economical and touristic activities to serious damages. The aim of this study is therefore to evaluate the erosion risk of the southern portion of the Molise coast, stretching from the Termoli promontory to the Saccione Stream mouth, a coastal zone characterized by intense shoreline evolution. The methodology used for the overall estimation of coastal risk involves the evaluation of two synthetic indexes. The first concerns the evaluation of the susceptibility to erosion (ISE) obtained by the linear correlation of four sub-indexes, which characterize the coastal system in terms of morphologies of beach and dune systems, shoreline evolution and wave climate effect. The second index analyzes the exposure to erosion by means of a method that is based on the assessment of the socio-economic value S (population, degree of urbanization and high ecological value) and potential damage D (in economic terms and in human lives) whose combination leads to the estimation of the exposure value index Ex. Finally, the coastal erosion risk R is evaluated through the matrix product between susceptibility and exposure indexes. Based on obtained R values, the study area is divided into four risk classes. The application of this methodology allowed dividing the southern coast of Molise in 33 sectors with different levels of erosion risk. In detail, 2 km and 6 km of the coastal area refer respectively to very high erosion (R4 class) and high erosion risk (R3 class). They correspond to 15 % and 41 % of the study area, respectively, and are mostly situated south of the Biferno River mouth (Lido di Campomarino) and south of the Campomarino harbor (Nuova Cliternia). These coastal areas have a high socio-economic and environmental value due to the presence of tourist infrastructure (Campomarino Lido) and protected ecological areas (SCI IT7222216 and SCI IT7222217). Their high level of risk, therefore, has a high impact on both human activities and the biodiversity conservation of the dune systems that host protected and endangered species. The results obtained in this study have highlighted the need for an integrated territorial management that takes into account not only individual local needs and urgencies but also the global coastal equilibrium of the Molise coast. In this context, the proper maintenance of coastal defense structures along the littoral and the definition of strategic plans for the defense and recovery of dunes could contribute to an important risk value reduction and to the coastal system resilience increase.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11695/72461
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