Assessing the resiliency of a coastal foredune in a changing climate
Notice bibliographique
Résumé
The north shore of Prince Edward Island (PEI) is one of the most vulnerable coastlines in Canada to climate change impacts due to tectonic subsidence exacerbating effects of global mean sea level rise (GMSLR), increase in the frequency and intensity of extreme storms including remnants of hurricanes tracking from the south-western Atlantic, and a reduction in protective winter sea ice, which typically fastens to the beach and buffers high energy winter waves. The barrier islands along the north shore serve as a protective buffer to coastal infrastructure and critical ecosystems from storm surge and wave impacts. The resiliency of a coastal barrier depends on the severity of impact from major storms, and the ability for the barrier to recover between subsequent storms with sediment from offshore, nearshore and alongshore sources. Following storm impact, sediment is transported from the nearshore to the beach face via low energy waves, and subsequently towards the foredune during episodic events of high wind energy. Quantification of post-storm recovery gives insight into the past, and future resiliency of a foredune system with regards to the prospect of a changing climate, including the increase in frequency of extreme storms. Lack of consistent, and morphologically accurate boundaries can render quantifications of sediment exchange inaccurate, and unreliable for projecting future changes to the system. There is a need to identify an unbiased, process-based dune toe, which delineates the end of the backshore and beginning of the foredune. This position is especially important when considering exchanges in sediment, including the changes in foredune and beach volume preceding and following a storm event. In this Dissertation, the impact of storms at Brackley Beach (BB) in Prince Edward Island (PEI) are quantified (Chapters 2 & 3), new techniques for characterizing beach-dune boundaries and sediment exchanges are introduced (Chapters 3 & 4), all known boundary delineation methods are critically analysed (Chapter 4), and decadal-scale evolution of the barrier is characterized (Chapter 5). In Chapters 2 and 3, volumetric loss following major storms Post-Tropical Storm Dorian (SD) in 2019 and Hurricane Fiona (HF) in 2022 are quantified with average alongshore losses of 1.7 and 42 m3 m-1 to the foredune. Additionally, Chapter 3 introduces a new method for remotely monitoring sediment exchanges using citizen science imagery. In Chapter 4, well-recognized dune toe delineation methods are compared throughout the SD and HF impact and recovery time series. An adaptation to the Relative Relief (RR) method, the modified RR method (MRR) proved to both accurately quantify sediment exchanges between the beach and dune, and outlined a process transition zone from the beach to the backshore. Finally, in Chapter 5, historical and present resiliency of the BB foredune system is modelled, finding that in the future BB will be unlikely to make a full recovery following HF due to climate change altering the equilibrium of storm impact and recovery.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,002 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».