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Flood risk assessment in climate change scenarios in the Algarve region
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Os riscos naturais são eventos extremos que colocam em risco as pessoas e seus pertences. Um dos mais
perigosos em termos de danos económicos e impactos na sociedade são as inundações. Com as
alterações climáticas é provável que a sua frequência e intensidade aumentem no futuro, o que,
juntamente com alterações no uso da terra, pode aumentar o risco de inundações. Para avaliar o risco de
inundação, a União Europeia aprovou uma Diretiva sobre a avaliação e gestão do risco de inundação,
que foi implementada na lei portuguesa. A avaliação do risco de inundação é importante para avaliar
onde este é muito alto e as medidas de mitigação que precisam de ser aplicadas. Esta tese teve como
objetivo produzir mapas de suscetibilidade (extensão, profundidade e velocidade de cheias), mapas de
perigosidade e risco para a cidade de Tavira no sul de Portugal. A análise utilizou dois períodos de
retorno (T20 e T100) para os eventos de inundação e considerou cenários de alterações climáticas para
três períodos futuros (2011-2040, 2041-2071, 2071-2100). A avaliação foi realizada por meio de
sistemas de geoinformação. O risco foi avaliado em termos de risco económico, social e ambiental,
sendo o risco económico calculado como o dano médio anual. Além disso, foram calculados os danos
absolutos decorrentes de um único evento de inundação. O risco económico foi obtido por meio de
curvas profundidade-dano e curvas de probabilidade-dano. O risco social foi calculado como a média
anual da população afetada e a probabilidade de focos sociais serem afetados. Para o risco ambiental,
foram identificadas fontes que podem causar poluição e discutidos os possíveis impactos no Parque
Nacional Rio Formosa. Os resultados demonstram um aumento na intensidade dos eventos de inundação
dos cenários T20 para os cenários T100, e também quando se propagam mais no futuro. Os valores mais elevados relativos à profundidade e velocidade de inundação, perigo e risco de inundação concentram-se nas proximidades do rio Gilão (que atravessa Tavira) e diminuem à medida do afastamento deste
curso de água. Grande parte da extensão da inundação afeta as salinas na parte sul da cidade.
Natural hazards are extreme events that endanger people and their belongings. One of the most dangerous in terms of economic damages and impacts on the society are floods. Through climate change it is likely that their frequency and intensity will increase in the future, which together with land use changes can increase the flood risk. In order to assessthe risk emerging from floods, the European Union passed a Directive on the assessment and management of flood risk, that was implemented in Portuguese law. The assessment of flood risk is important to evaluate where the risk is too high and mitigation measurements need to be applied. This thesis aimed at producing hazard maps (flood extent, depth and velocity), danger, and risk maps for the city of Tavira in southern Portugal. The analysis used two return periods (T20 and T100) for the flood events and considered climate change scenarios for three future time periods (2011-2040, 2041-2071, 2071-2100). The assessment was performed using geoinformation systems. The risk was evaluated in terms of the economic, social, and environmental risk, whereby the economic risk was calculated as the annual average damage. Besides that, the absolute damage emerging from one single flood event was calculated. The economic risk was obtained using depth-damage curves and probability-damage curves. The social risk was calculated as the annual average affected population and the probability of social hot spots being affected. For the environmental risk, sources that might cause pollution were identified and the possible impacts on the National Park Rio Formosa were discussed. There is a definite increase in the intensity of the flood events from the T20-scenarios to the T100-scnearios, and also when propagating further in the future. The highest values regarding the flood depth, flood velocity, flood danger and risk can be found in near distance to the river Gilão (that runs through Tavira) and are decreasing with higher distances to it. A big part of the flood extent affects the salines in the southern part of the city.
Natural hazards are extreme events that endanger people and their belongings. One of the most dangerous in terms of economic damages and impacts on the society are floods. Through climate change it is likely that their frequency and intensity will increase in the future, which together with land use changes can increase the flood risk. In order to assessthe risk emerging from floods, the European Union passed a Directive on the assessment and management of flood risk, that was implemented in Portuguese law. The assessment of flood risk is important to evaluate where the risk is too high and mitigation measurements need to be applied. This thesis aimed at producing hazard maps (flood extent, depth and velocity), danger, and risk maps for the city of Tavira in southern Portugal. The analysis used two return periods (T20 and T100) for the flood events and considered climate change scenarios for three future time periods (2011-2040, 2041-2071, 2071-2100). The assessment was performed using geoinformation systems. The risk was evaluated in terms of the economic, social, and environmental risk, whereby the economic risk was calculated as the annual average damage. Besides that, the absolute damage emerging from one single flood event was calculated. The economic risk was obtained using depth-damage curves and probability-damage curves. The social risk was calculated as the annual average affected population and the probability of social hot spots being affected. For the environmental risk, sources that might cause pollution were identified and the possible impacts on the National Park Rio Formosa were discussed. There is a definite increase in the intensity of the flood events from the T20-scenarios to the T100-scnearios, and also when propagating further in the future. The highest values regarding the flood depth, flood velocity, flood danger and risk can be found in near distance to the river Gilão (that runs through Tavira) and are decreasing with higher distances to it. A big part of the flood extent affects the salines in the southern part of the city.
Descrição
Tese de Mestrado, Geologia do Ambiente, Riscos Geológicos e Ordenamento do Território, 2022, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Análise de risco de inundação Avaliação de risco de inundação Alterações climáticas Curva profundidade-dano Mapas de risco Teses de mestrado - 2022