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Publication
Erosão e Galgamentos na Costa Portuguesa
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| 6.51 MB | Adobe PDF |
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Abstract(s)
Neste trabalho avaliaram-se os resultados da implementação dos instrumentos de gestão territorial na ocupação do espaço costeiro em Portugal, bem como a eficácia das medidas propostas e suas implementações ao longo dos últimos anos, nas alterações à exposição do risco de erosão e galgamentos costeiros. A opção de escolha deste estudo deveu-se, fundamentalmente, à importância na identificação, resolução e mitigação dos problemas da zona costeira portuguesa, nomeadamente no facto de esta assumir uma importante estratégia no que diz respeito à política de desenvolvimento sustentável do nosso país, e ao seu enquadramento numa gestão integrada e coordenada destas áreas. O trabalho consistiu, essencialmente, na avaliação do atual estado da arte no que diz respeito ao que tem vindo a ser feito, analisando a mais valia dos investimentos nas medidas implementadas nas últimas décadas, com especial incidência em dois casos de estudo, considerados dos mais representativos da atual realidade da nossa costa. Os estudos focados evidenciam essas fragilidades, associadas a um excesso de confiança nas defesas costeiras adotadas, bem como a vulnerabilidade a que as comunidades estão sujeitas. Torna-se, pois, urgente garantir a segurança de toda a costa de forma a mitigar o avanço do mar em direção a terra sendo, para isso, importante analisar e encontrar soluções que permitam alcançar um equilíbrio na dinâmica sedimentar. Assim, entende-se como prioritária a criação de um depósito maior de inertes nas zonas junto à costa permitindo, desta forma, o efeito de perda de energia das ondas na sua rebentação, resultando na redução do seu espraiamento pela costa. Através da utilização de novas técnicas entretanto desenvolvidas, em detrimento das técnicas de ripagem classicamente usadas, as quais consistem na utilização de um processo mecânico de Bypass – solução nunca testada em Portugal – usando sistemas de bombagem permanente, seria possível transportar areias submersas de locais de maior acumulação, para as zonas mais carenciadas, permitindo assim a sua reposição nas zonas costeiras que se encontram com um forte défice sedimentar.
This work evaluated the results on the implementation of territorial management instruments in the occupation of coastal space in Portugal, as well as the effectiveness of the proposed measures and their implementations over the past few years, on changes in exposure to erosion risk and coastal gaps. The choice of this study was fundamentally due to the importance on identifying, solving and mitigating the problems of the Portuguese coastal zone, in particular the fact that it assumed an important strategy regarding our country's sustainable development policy, and its integrated and coordinated management of these areas. The work consisted mainly on evaluating the current state of the art on what has been already done, analysing the added value of investments in the measures implemented during the last decades, with a special focus on two case studies considered to be the most representative of the current reality of our coast. The focused studies highlighted these weaknesses, associated with overconfidence in the coastal defences adopted, as well as the vulnerability to which communities are subject. Therefore, it is urgent to ensure the safety of the whole coast in order to mitigate the sea progress towards the land and, for this reason, it is important to analyse and find solutions that allow a balance in the sedimentary dynamics. Thus, it is understood as a priority to create a larger deposit of aggregates in the areas near the coast, allowing the effect of energy loss of the waves in their surfacing, resulting in the reduction of their spreading by the coast. Through the use of new techniques recently developed, instead of those classical ripping techniques from the past, which consist of the use of a mechanical Bypass – a solution not yet tested in Portugal – using permanent pumping systems, it would be possible to transport submerged sands from greater accumulation, to the most deprived areas, thus allowing them to be replenished on the coastal zones that have a strong sedimentary deficit.
This work evaluated the results on the implementation of territorial management instruments in the occupation of coastal space in Portugal, as well as the effectiveness of the proposed measures and their implementations over the past few years, on changes in exposure to erosion risk and coastal gaps. The choice of this study was fundamentally due to the importance on identifying, solving and mitigating the problems of the Portuguese coastal zone, in particular the fact that it assumed an important strategy regarding our country's sustainable development policy, and its integrated and coordinated management of these areas. The work consisted mainly on evaluating the current state of the art on what has been already done, analysing the added value of investments in the measures implemented during the last decades, with a special focus on two case studies considered to be the most representative of the current reality of our coast. The focused studies highlighted these weaknesses, associated with overconfidence in the coastal defences adopted, as well as the vulnerability to which communities are subject. Therefore, it is urgent to ensure the safety of the whole coast in order to mitigate the sea progress towards the land and, for this reason, it is important to analyse and find solutions that allow a balance in the sedimentary dynamics. Thus, it is understood as a priority to create a larger deposit of aggregates in the areas near the coast, allowing the effect of energy loss of the waves in their surfacing, resulting in the reduction of their spreading by the coast. Through the use of new techniques recently developed, instead of those classical ripping techniques from the past, which consist of the use of a mechanical Bypass – a solution not yet tested in Portugal – using permanent pumping systems, it would be possible to transport submerged sands from greater accumulation, to the most deprived areas, thus allowing them to be replenished on the coastal zones that have a strong sedimentary deficit.
Description
Keywords
Erosão Costeira, Galgamentos, Impactes, Mitigação Coastal Erosion, Gouges, Impacts, Mitigation.