Climate change impacts on critical international transportation assets of Caribbean Small Island Developing States (SIDS): the case of Jamaica and Saint Lucia

This contribution presents an assessment of the potential vulnerabilities to climate variability and change (CV & C) of the critical transportation infrastructure of Caribbean Small Island Developing States (SIDS). It focuses on potential operational disruptions and coastal inundation forced by CV & C on four coastal international airports and four seaports in Jamaica and Saint Lucia which are critical facilitators of international connectivity and socioeconomic development. Impact assessments have been carried out under climatic conditions forced by a 1.5 °C specific warming level (SWL) above pre-industrial levels, as well as for different emission scenarios and time periods in the twenty-first century. Disruptions and increasing costs due to, e.g., more frequent exceedance of high temperature thresholds that could impede transport operations are predicted, even under the 1.5 °C SWL, advocated by the Alliance of Small Island States (AOSIS) and reflected as an aspirational goal in the Paris Climate Agreement. Dynamic modeling of the coastal inundation under different return periods of projected extreme sea levels (ESLs) indicates that the examined airports and seaports will face increasing coastal inundation during the century. Inundation is projected for the airport runways of some of the examined international airports and most of the seaports, even from the 100-year extreme sea level under 1.5 °C SWL. In the absence of effective technical adaptation measures, both operational disruptions and coastal inundation are projected to increasingly affect all examined assets over the course of the century

Integrated estimation of coastal erosion due to sea level rise

Beach erosion is a major global problem with serious physical and socio-economic impacts. Beach erosion can be differentiated into: (i) long-term erosion, i.e. irreversible retreat of the shoreline position, mainly due to sea level rise; and (ii) short-term erosion, caused by storms and storm surges, which may not necessarily result in permanent shoreline retreats. The main objective of the present study is to develop a new methodology/tool that will be able to assess the range of the beach retreat for different morphologically beaches, under different scenarios of long-term and short-term sea level rise and different conditions and forcings. Towards this objective (a) a state-of-the-art 1-D morphodynamic model based on nonlinear breaking wave Boussinesq-type equations and (b) ensembles (a short-term and a long-term) of analytical and numerical morphodynamic models of varied complexity are used.The study showed (a) that all models predict significant coastal retreats due to the predicted sea level rise, (b) differential sensitivity of the models to the morphological, sedimentary and hydrodynamic conditions, and (c) that the range of predictions resulted by the sophisticated Boussinesq model is similar to that of the ensembles, although these consist of more simple models. Many different dissipative and intermediate beaches were examined. The envelope of beach retreat under different scenarios of sea level rise was estimated, the minimum and maximum limits of which were found to be described by the following expressions: s = 0.39 α2 + 8.87 α - 0.25 (minimum) and s = -0.82 α2 +32.43 α +0.81 (maximum) (Boussinesq model)• and s = 0.33 α2 + 7.4 α – 0.14 (minimum) and s = 0.74 α2 + 28.9 α +4.9 (maximum) (integrated ensemble), where s the beach retreat and α the sea level rise. The coherence of the means of the ensembles with the elaborate Boussinesq model that has been validated by experiments, suggests that these models operate well in an ensemble manner. Nevertheless, the coherence of the results does not quarantee the detailed description of the beach erosion processes for individual beaches• it shows, however, the validity of the uppermost and lowermost limits of the predictions, which can be used for general applications and large-scale forecasts of beach erosion/retreat due to sea level rise. The tool suggested in the present work is fast and easy to use, has insignificant cost of application, does not require particular know-how and can be used, by almost anyone, for a rapid assessment of the beach erosion caused by sea level rise at various spatial scales (from local to global). Its only requirement for worst-case scenario projections is the width of the beach.Η παράκτια διάβρωση, η οποία αποτελεί σήμερα ένα σημαντικότατο φυσικό και κοινωνικο-οικονομικό πρόβλημα, διακρίνεται σε: (i) μακροχρόνια διάβρωση, δηλαδή μη αναστρέψιμη μακροχρόνια οπισθοχώρηση της ακτογραμμής, λόγω ανόδου της θαλάσσιας στάθμης και/ή αρνητικών παράκτιων ιζηματικών ισοζυγίων και (ii) βραχυχρόνια διάβρωση, η οποία οφείλεται κυρίως σε ακραία φαινόμενα (μετεωρολογικές παλίρροιες (storm surges) και θυελλώδεις κυματισμούς), τα οποία μπορεί να μην προκαλούν μόνιμες οπισθοχωρήσεις της ακτογραμμής. Ο κύριος σκοπός της παρούσας μελέτης είναι η ανάπτυξη μιας νέας μεθοδολογίας/εργαλείου για την διάγνωση και πρόβλεψη της παραλιακής οπισθοχώρησης κάτω από διαφορετικές μακροχρόνιες και βραχυχρόνιες ανόδους της θαλάσσιας στάθμης και διαφορετικές μορφολογικές, υδροδυναμικές και ιζηματολογικές οδηγήσεις. Για την επίτευξη του στόχου χρησιμοποιήθηκαν: (α) ένα προηγμένο 1-D μορφοδυναμικό μοντέλο, που βασίζεται στις εξισώσεις διασπειρόμενων, μη γραμμικών κυματισμών τύπου Boussinesq και (β) 2 συστοιχίες (1 βραχυχρόνια και 1 μακροχρόνια) διαφορετικών αναλυτικών και αριθμητικών μορφοδυναμικών μοντέλων. Η μελέτη έδειξε (α) ότι όλα τα μοντέλα προβλέπουν σημαντική παράκτια οπισθοχώρηση λόγω της προβλεπόμενης ανόδου της μέσης θαλάσσιας στάθμης, (β) διαφορετική ευαισθησία των μοντέλων στις μορφολογικές, ιζηματολογικές και υδροδυναμικές συνθήκες και (γ) ότι το εύρος των εκτιμήσεων του εξελιγμένου μοντέλου Boussinesq είναι παρόμοιο με εκείνο των συστοιχιών που αποτελούνται από πιο απλά και εύχρηστα μοντέλα. Έγινε παραμετροποίηση της παραλιακής οπισθοχώρησης έπειτα από έναν μεγάλο αριθμό πειραμάτων (23528) και βρέθηκε ότι για απορροφητικές και ενδιάμεσες παραλίες τα κατώτερα και ανώτερα όρια της διάβρωσης δίνονται από τις ακόλουθες εκφράσεις: s = 0.39 α2 + 8.87 α - 0.25 (κατώτερο) και s = -0.82 α2 +32.43 α +0.81 (ανώτερο) (μοντέλο Boussinesq)• και s = 0.33 α2 + 7.4 α – 0.14 (κατώτερο) και s = 0.74 α2 + 28.9 α +4.9 (ανώτερο) (ενιαία συστοιχία 5 μοντέλων), όπου s η παραλιακή οπισθοχώρηση και α η άνοδος της θαλάσσιας στάθμης. Η συνάφεια των αποτελεσμάτων των συστοιχιών με το μοντέλο Boussinesq το οποίο έχει αξιολογηθεί με φυσικά πειράματα σημαίνει ότι τα μοντέλα αυτά δουλεύουν καλά με τη μορφή της συστοιχίας. Η συνάφεια αυτή δεν εγγυάται τη χρήση των συστοιχιών για τη λεπτομερή περιγραφή των διεργασιών οπισθοχώρησης σε μεμονωμένες παραλίες• αποδεικνύει όμως την εγκυρότητα των ανώτερων και κατώτερων ορίων των προβλέψεων τους, των οποίων ενδείκνυται η χρήση για γενικευμένες εφαρμογές και για μεγάλης κλίμακας προβλέψεις. Το εργαλείο που αναπτύχθηκε στην παρούσα μελέτη (αντίθετα με όλα τα υπάρχοντα εργαλεία) έχει πολύ μικρό/μηδαμινό κόστος εφαρμογής, είναι εύκολο και γρήγορο στην εφαρμογή του, δεν απαιτεί ιδιαίτερη τεχνογνωσία και μπορεί να χρησιμοποιηθεί εύκολα από κάποιο παράκτιο μελετητή/διαχειριστή που θέλει να έχει μια πρώτη εκτίμηση της διάβρωσης που θα προκληθεί από την άνοδο της θαλάσσιας στάθμης σε μεγάλες χωρικές κλίμακες. Η μόνη απαίτηση σε περιβαλλοντικά δεδομένα είναι πληροφορία σχετική με το παραλιακό εύρος, η οποία όμως μπορεί να βρεθεί εύκολα από web-GIS εφαρμογές (π.χ. Google Earth)

Assessment of and Adaptation to Beach Erosion in Islands: An Integrated Approach

Island beaches, which form significant natural and economic resources, are under increasing erosion risk due to sea level rise. The present contribution proposes an integrated methodological framework for the evaluation of the socio-economic significance of beaches and their vulnerability to sea level rise and the design of effective adaptation measures. The approach comprises four steps: (i) beach ranking on the basis of their socio-economic significance and vulnerability in order to prioritize adaptation responses; (ii) monitoring of the hydro- and morphodynamic regime of the most highly ranking beaches using field observations and modelling, (iii) assessment of the sediment volumes required for beach nourishment under different scenarios of sea level rise and nourishment designs; (iv) evaluation of the marine aggregate potential of the adjacent areas that can be used for beach nourishment. The framework was applied to the Greek island of Chios, which has many beaches that are already under erosion. The methodology was shown to provide a structured approach for the assessment and response to erosion of the most vulnerable beach

Beaches

Maximum beach retreat (in percentage of the maximum beach width) predicted by the model ensemble for the Black Sea beaches under a 0.5 m SLR (coastal retreat estimated to 21.4 m.)

Black Sea beaches vulnerability to sea level rise

Integrated Coastal Zone Management (ICZM) aims to promote sustainable management of coastal zones based on ecosystem and holistic management approaches. In this context, policies have to consider the complex interactions that influence the fragile equilibrium of coastal ecosystems. Beaches represent both valuable and vulnerable natural resources because of the various ecosystem services they provide and their sensitivity to climate change and sea level rise. We present the first comprehensive digital record of all Black Sea beaches and provide a rapid assessment of their erosion risk under different scenarios of sea level rise. Through the digitisation of freely available remote-sensed images on the web, we provide broad information on the spatial characteristics and other attributes of all Black Sea beaches (e.g. photo-based visual estimation of the sediment type, presence of coastal defences, urban development). These data have been assembled and stored in full Spatial Data Infrastructure (SDI) – allowing spatial queries, visualisation and data sharing – and are therefore particularly interesting to feed/supply web-GIS portals (coastal atlases) for visualisation purpose, spatial queries or spatial indicators calculations. The resulting Black Sea beaches database contains 1228 beaches, with a total coast-line length of 2042 km with an area of 224 km2. The majority of the Black Sea beaches have been found to have small widths (61% have maximum widths less than 50 m), whereas 47% of all beaches presented coastal defence schemes, suggesting an already serious beach erosion problem. The erosion risk of the Black Sea beaches was assessed through the comparison of their maximum widths with estimations of the sea level rise-induced retreat by an ensemble of six 1-D analytical and numerical morphodynamic models. Following more than 17,000 experiments using different combinations of wave conditions, beach sediment textures and slopes and 11 scenarios of sea level rise (up to 2 m), the means (best fits) of the lowest and highest projections by the model ensemble were estimated; these were then compared to the maximum widths of the Black Sea beaches. The analysis showed that sea level rise will have highly significant impacts on the Black Sea beaches, as for a 0.5 m sea level rise 56% of all beaches are projected to retreat by 50% of their maximum width. For a 0.82 m sea level rise (the high IPCC estimate for the period 2081–2100) about 41% are projected to retreat by their entire maximum width, whereas for 1 m sea level rise about 51% of all Black Sea beaches are projected to retreat by (drowned or shifted landward by) their entire maximum width, if the high mean of the model ensemble projections is used. Results substantiate the risk of beach erosion as a major environmental problem along the Black Sea coast, which therefore needs to be taken into account in any future coastal management plans, as a matter of urgency. As these scenarios consider only sea level rise, they are considered to be conservative. Although the present results cannot replace detailed studies, the database and projections may assist Black Sea coastal managers and policy makers to rapidly identify beaches with increased risk of erosion, valuate accordingly coastal assets and infrastructure, estimate beach capacity for touristic development purposes, and rapidly assess direct and indirect costs and benefits of beach protection options. They also provide the necessary inputs to advance discussions relevant to the Black Sea ICZM

Climate change - induced hazards on touristic island beaches: Cyprus, Eastern Mediterranean

This contribution presents an assessment at a regional (island) scale of the beach erosion due to storm events under Climate Change. The approach adopted to assess beach erosion at the island scale consisted of three modules. First, the location, dimensions and other attributes of the Cypriot beaches were recorded on the basis of widely-available satellite imagery. Secondly, sea levels and waves were modeled along the coast under different climatic scenarios and dates in the 21st century. Finally, using these projections beach retreat due to the relative mean sea level rise (RSLR) and extreme sea levels (ESLs) was estimated using ensembles of analytical and numerical cross-shore morphodynamic models, respectively. Extreme sea levels (ESLs) were projected to (a) increase by up to 60% in 2100 from their baseline (2000) levels, and (b) vary along the coast, with the highest ESLs (and corresponding waves) projected for the southern and western coasts. The mostly narrow Cypriot beaches (91% recorded maximum widths of < 50 m) showed increased exposure to erosion. In 2100, about 47% and 72% (based on the median model estimates) of the 241 unprotected Cypriot beaches will be permanently eroded, due to mean sea level rise (SLR), to 50% of their present maximum width, depending on the scenario. In addition to the long-term erosion due to SLR, severe storm erosion is projected by 2050 even under the RCP4.5 scenario; the 100-year extreme sea level event (ESL100) may overwhelm (at least temporarily) 49% of the currently unprotected Cypriot beaches without effective adaptation responses, with the most exposed beaches located along the northern coast. As the beach carrying capacity and hedonic value will be severely compromised, effective adaptation policies and technical measures will be urgently required.Hydraulic Structures and Flood Ris