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Monitorização da resiliência e vulnerabilidade a pressões naturais e antrópicas em sistemas praia-duna
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Orientador(es)
Resumo(s)
A importância ambiental e social, nomeadamente em termos recreativos, das zonas
costeiras para a respetiva região ou país a que pertencem é indiscutível. Para além disto, a sua
relevância económica contribui para o seu sobrepovoamento, podendo-se ter, como consequências, o aumento de tráfego rodoviário e a intensificação de atividades industriais, que
contribuem para o agravamento das Alterações Climáticas (AC). Estes fatores, entre outros,
sujeitam os sistemas litorais a pressões que podem comprometer a sua capacidade de resiliência a eventos extremos. Assim, geram-se diversos conflitos de interesses nos usos dos mesmos, que conduzem à necessidade de efetuar a sua proteção reativa. Os Instrumentos de Gestão do Território (IGT) visam o planeamento e gestão da ocupação destes frágeis territórios, a
fim de preservar os seus recursos. Porém, a falta de fiscalização e a delegação constante de
responsabilidades entre as entidades com obrigações de ordenamento traduz-se, na prática,
na exposição de pessoas e bens aos riscos costeiros.
As checklists são ferramentas bastante difundidas que permitem uma avaliação da vulnerabilidade do sistema através da análise de parâmetros específicos, cuja aplicabilidade pode
ser verificada no campo. Cada uma delas permite a determinação do respetivo índice de vulnerabilidade através da atribuição de ponderações às variáveis, correspondentes aos níveis de
vulnerabilidade, a fim de as converter todas à mesma escala. Verificou-se que existem três checklists clássicas diferentes aplicáveis a sistemas atlânticos, duas que analisam a vulnerabilidade considerando pontuações de 0 a 4, e uma que considera níveis de 0 a 2.
O troço costeiro da Costa da Caparica tem sido bastante fustigado por tempestades de
diferentes intensidades, sendo um dos territórios mais vulneráveis à erosão e recuo da linha
de costa. Posto isto, esta Dissertação visou a monitorização do estado de vulnerabilidade do
cordão dunar de S. João da Caparica após a ocorrência do furacão Erin, tendo-se aplicado as três checklists, sendo uma principal (root checklist), e duas secundárias (resiliência e GAVAM).
Para além disso, visou a criação de uma lista totalmente aplicável à praia de São João, correspondente à área de estudo, mas também a outras periurbanas, tendo por base as listas pré-existentes, mas com as devidas correções face ao observado no local.
Todavia, para as três listas, obtiveram-se valores de vulnerabilidade no intervalo baixo a
médio, sendo que os resultados da root checklist e da GAVAM se encontraram mais próximos,
o que se pode ter devido, entre outras razões, ao facto de ambas usarem uma escala de 0 a 4.
Estes resultados coadunaram-se com os de outros estudos efetuados neste território, tanto de
investigações que avaliaram a vulnerabilidade com recurso às
checklists resiliência e GAVAM,
como de investigações que determinaram o balanço sedimentar da praia, de onde foi possível
inferir a sua vulnerabilidade aproximada. Para além disso, os resultados obtidos fizeram sentido, face ao sucesso comprovado de duas fases de implementação do projeto ReDuna.
The environmental and social importance of coastal areas for the respective region or country to which they belong, namely in terms of recreation, is indisputable. In addition, their economic relevance contributes to their overpopulation, which can result in increased road traffic and intensified industrial activities, contributing to the worsening of climate changes. These factors, among others, subject coastal systems to pressures that can compromise their resilience to extreme events. This generates various conflicts of interest in their use, leading to the need for reactive protection. Land Management Instruments aim to plan and manage the occupation of these fragile territories in order to preserve their resources. However, the lack of supervision and the constant delegation of responsibilities between entities with planning ob- ligations translates, in practice, into the exposure of people and property to coastal risks. Checklists are popular tools that allow for an assessment of system vulnerability through the analysis of specific parameters, whose applicability can be checked in the field. Each check- list allows for the determination of the respective vulnerability index by assigning weights to variables corresponding to vulnerability levels in order to convert them all to the same scale. It has been found that there are three different classic checklists applicable to Atlantic systems, two of that analyses vulnerability using scores from 0 to 4, and the other considers levels from 0 to 2. The coastal stretch of Costa da Caparica has been severely affected by storms of different intensities, making it one of the most vulnerable areas to coastal erosion and retreat. Therefore, this work aimed to monitor the vulnerability of the S. João da Caparica dune system after Erin hurricane, applying the three checklists: one main checklist (root checklist) and two secondary (resilience and GAVAM). In addition, it aimed to create a checklist that is fully applicable to São João beach, corresponding to the study area, but also to other peri-urban beaches, based on the pre-existing ones, but with the necessary corrections in view of what was observed on site. However, for all three lists, vulnerability values obtained ranged from low to medium, with the results of the root and GAVAM checklists being closer together, which may be due, among other reasons, to the fact that both use the same scale, i.e., from 0 to 4. These range were consistent with the obtained on other studies carried out in this territory, both from re- search that assessed vulnerability using the resilience and GAVAM checklists, and from re- search that determined the sediment balance of the beach, from which it was possible to infer its approximate vulnerability. Furthermore, the results got made sense, given the proven suc- cess of two phases of implementation of the ReDuna project.
The environmental and social importance of coastal areas for the respective region or country to which they belong, namely in terms of recreation, is indisputable. In addition, their economic relevance contributes to their overpopulation, which can result in increased road traffic and intensified industrial activities, contributing to the worsening of climate changes. These factors, among others, subject coastal systems to pressures that can compromise their resilience to extreme events. This generates various conflicts of interest in their use, leading to the need for reactive protection. Land Management Instruments aim to plan and manage the occupation of these fragile territories in order to preserve their resources. However, the lack of supervision and the constant delegation of responsibilities between entities with planning ob- ligations translates, in practice, into the exposure of people and property to coastal risks. Checklists are popular tools that allow for an assessment of system vulnerability through the analysis of specific parameters, whose applicability can be checked in the field. Each check- list allows for the determination of the respective vulnerability index by assigning weights to variables corresponding to vulnerability levels in order to convert them all to the same scale. It has been found that there are three different classic checklists applicable to Atlantic systems, two of that analyses vulnerability using scores from 0 to 4, and the other considers levels from 0 to 2. The coastal stretch of Costa da Caparica has been severely affected by storms of different intensities, making it one of the most vulnerable areas to coastal erosion and retreat. Therefore, this work aimed to monitor the vulnerability of the S. João da Caparica dune system after Erin hurricane, applying the three checklists: one main checklist (root checklist) and two secondary (resilience and GAVAM). In addition, it aimed to create a checklist that is fully applicable to São João beach, corresponding to the study area, but also to other peri-urban beaches, based on the pre-existing ones, but with the necessary corrections in view of what was observed on site. However, for all three lists, vulnerability values obtained ranged from low to medium, with the results of the root and GAVAM checklists being closer together, which may be due, among other reasons, to the fact that both use the same scale, i.e., from 0 to 4. These range were consistent with the obtained on other studies carried out in this territory, both from re- search that assessed vulnerability using the resilience and GAVAM checklists, and from re- search that determined the sediment balance of the beach, from which it was possible to infer its approximate vulnerability. Furthermore, the results got made sense, given the proven suc- cess of two phases of implementation of the ReDuna project.
Descrição
Palavras-chave
Zonas costeiras limiar de resiliência capacidade de carga proteção costeira estratégias de adaptação gestão do território