Perdas nos valores dos ecossistemas devido à erosão costeira (Portugal)
Portugal é dos países da Europa onde os processos de erosão costeira são mais evidenciados. As zonas costeiras têm vindo a presenciar o aumento das taxas de erosão costeira, que ocorrem devido a vários factores como a subida do nível do mar, o aumento da frequência de tempestades, a redução na alimentação de sedimentos à costa e alterações de origem antrópica. Para além da erosão costeira, a zona costeira portuguesa está assim sujeita a um conjunto de riscos, como a desregulação do funcionamento natural dos ecossistemas costeiros e a perda da biodiversidade. Apesar destes impactes da erosão costeira estarem confinados à zona costeira, é importante ter em atenção que destas áreas fazem parte grandes cidades, e como tal, alberga grande parte da população, bem como uma vasta variedade de ecossistemas que proporcionam uma série de serviços ambientais. Estes ecossistemas, assim como os valores associados, podem ser perdidos devido à erosão costeira. Vários estudos têm sido desenvolvidos para a zona costeira, quer relativamente à sua gestão, à sua defesa ou ao valor dos ecossistemas. Muitos destes estudos avaliam factores físicos, morfológicos, ambientais, e económicos quer ao nível histórico, quer fazendo projecções para o futuro. No entanto poucos avaliam as perdas nos valores dos ecossistemas devido à erosão costeira. Neste sentido, a presente Dissertação visa avaliar as perdas históricas nos valores dos ecossistemas devido à erosão costeira, ocorridas em Portugal continental entre 1975 e 2006. Para tal é aplicada uma abordagem económico-ambiental, que combina os padrões do uso do solo histórico com técnicas de transferência de benefícios. Os resultados demonstram que os ecossistemas costeiros em Portugal possuíam valores elevados (cerca de 1.535m€/ano em 1975) que têm vindo a diminuir ao longo dos anos (até cerca de 1.468m€/ano em 2006) devido às alterações na ocupação e usos do solo na região costeira considerada, ou seja, ocorreu uma diminuição no valor anual dos ecossistemas costeiros de 67m€/ano. O território perdido devido à erosão costeira é de cerca de 1.924ha entre 1975 e 2006, sendo constituído maioritariamente por Praias, dunas e areias, cujo valor anual ambiental representa 43m€/ano. Neste sentido estima-se que cerca de 65% das perdas ocorridas nos valores dos ecossistemas na zona costeira portuguesa, são devidas aos processos de erosão costeira.
Portugal is one of Europe´s countries where coastal erosion processes are most evident. Coastal zones experience increased rates of coastal erosion, due to rising sea levels, increased storm surge frequencies, reduced sediment delivery and anthropic transformations. In addition to coastal erosion, the Portuguese coast is subject to a number of risks, such as the deregulation of the natural functioning of coastal ecosystems and biodiversity losses. These impacts of coastal erosion are usually limited to the coastal zone, however, it is important to note that these areas host large cities and, consequently, populations as well as a wide variety of ecosystems that provide a series of environmental services. These ecosystems, as well as their associated values, can be lost due to coastal erosion. Various studies have been developed for the coastal zone, regarding their management, their defense or their ecosystem values. Many of these studies evaluate historical and/or project future physical, morphological, environmental and economic aspects. However, few evaluate ecosystems service value losses due to coastal erosion. This thesis assesses the historical ecosystem service value losses due to coastal erosion that occurred in Portugal between 1975 and 2006. Hence, an environmental-economic approach is applied, combining historical land use patterns with benefits transfer techniques. Results show that coastal ecosystems in Portugal represent large values (about 1,535 m€/year in 1975) that have been declining over the years (till 1,468 m€/year in 2006) because of changes in land uses in the coastal region considered – i.e. there was a decrease in the annual value of coastal ecosystems of about 67m€/year. The area lost due to coastal erosion was approximately 1,924 ha between 1975 and 2006, comprising mainly Beaches, dunes and sands whose annual environmental value is estimated at 43m€/year. Hence, it is estimated that about 65% of coastal ecosystem service value losses in Portugal, are due to the coastal erosion process.
Portugal is one of Europe´s countries where coastal erosion processes are most evident. Coastal zones experience increased rates of coastal erosion, due to rising sea levels, increased storm surge frequencies, reduced sediment delivery and anthropic transformations. In addition to coastal erosion, the Portuguese coast is subject to a number of risks, such as the deregulation of the natural functioning of coastal ecosystems and biodiversity losses. These impacts of coastal erosion are usually limited to the coastal zone, however, it is important to note that these areas host large cities and, consequently, populations as well as a wide variety of ecosystems that provide a series of environmental services. These ecosystems, as well as their associated values, can be lost due to coastal erosion. Various studies have been developed for the coastal zone, regarding their management, their defense or their ecosystem values. Many of these studies evaluate historical and/or project future physical, morphological, environmental and economic aspects. However, few evaluate ecosystems service value losses due to coastal erosion. This thesis assesses the historical ecosystem service value losses due to coastal erosion that occurred in Portugal between 1975 and 2006. Hence, an environmental-economic approach is applied, combining historical land use patterns with benefits transfer techniques. Results show that coastal ecosystems in Portugal represent large values (about 1,535 m€/year in 1975) that have been declining over the years (till 1,468 m€/year in 2006) because of changes in land uses in the coastal region considered – i.e. there was a decrease in the annual value of coastal ecosystems of about 67m€/year. The area lost due to coastal erosion was approximately 1,924 ha between 1975 and 2006, comprising mainly Beaches, dunes and sands whose annual environmental value is estimated at 43m€/year. Hence, it is estimated that about 65% of coastal ecosystem service value losses in Portugal, are due to the coastal erosion process.
Universidade de Aveiro | http://hdl.handle.net/10773/8598
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