GEOHAZARDS IN PORTUGAL:

In Portugal, scholarly attention towards geohazards has grown significantly since the 1980s, with various analytical methods employed to study these phenomena, including physically-based models, data-driven models, and heuristic techniques. The published research has contributed to a better understanding of the underlying processes, but also includes the assessment of susceptibility, probability, and magnitude of hazardous events. Some studies have extended into risk analysis, considering exposure, asset valuation, and vulnerability, encompassing both physical and social dimensions. Geohazards are concentrated primarily in the western and southern coastal areas of mainland Portugal, particularly in regions like Lisbon, the Lower Tagus Valley, and the Algarve. These areas face multiple geohazard threats, including earthquakes, tsunamis, coastal erosion, floods, flash floods, and landslides. In the remaining parts of mainland Portugal, the inland North and Centre regions are more prone to landslides and soil erosion, while the Alentejo is comparatively safer but still faces a significant risk of soil erosion, contributing to the threat of desertification. Within the Atlantic islands, Madeira exhibits a notable susceptibility to landslides, flash floods, and coastal erosion, whereas the Azores islands encompass a wide spectrum of geohazards, comprising active volcanoes, earthquakes, tsunamis, landslides, flash floods, and coastal erosion

Extreme precipitation and floods in the Iberian Peninsula and its socio-economic impacts.

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Rural Fires: Causes of Human Losses in the 2017 Fires in Portugal

Extreme wildfires are increasingly rising to intense and uncontrolled fires, with dimension and destructive potentials that are greater than what has been seen and dealt with. The hazards posed by these fires increase significantly when they approach the wild–urban interface, with relevant environmental and socio-economic consequences. The 2009 Victorian bushfires and the 2017 Portugal wildfires are powerful reminders, and they have demonstrated the need to better understand why mitigation plans have failed to protect the community in these events and to improve community resilience. The year 2017 is a milestone in the history of wildfires in Portugal, not only because of the vast burned area but also due to the high number of fatalities. The two occurrences were at different times (June and October) but were geographically close (region of centre of Portugal). A total of 117 deaths occurred in both events and 92% of the victims were in wild–urban interface areas. This paper analyses and discusses the characteristics and causes of death of the victims of these two events: age, place of death, distance from place of death to place of residence and last-minute choices to aim to understand the actions that people took in the face of the approaching fire, which led to their death. In both cases, most people died fleeing the fire without any information from the competent authorities. In the end, it is possible to identify risk factors that lead to the death of civilians due to wildfires, such as the increase in demand for rurality by young people from big cities with no previous contact with wildfires; on the other hand, there is the ageing of the population residing in forest areas, who were previously physically and structurally prepared to deal with fires and are currently no longer able to.info:eu-repo/semantics/publishedVersio

A new approach to assess ancient marine slope instability using a bivariate statistical method

Slope instability is one of the most effective processes shaping the sea floor of continental margins. The end-products of slope instability, mass-transport deposits (MTDs), have been documented in the literature using diverse approaches. This paper tests a new methodology, applied to a region offshore Espírito Santo (SE Brazil), for the evaluation of MTDs' occurrence on continental slopes. A MTD inventory was, in a first stage, made for a cropped region of SE Brazil using a high resolution three-dimensional (3D) seismic volume. This MTD inventory consists of four MTDs that were mapped and exported into a Geographic Information Systems (GIS) database. MTD favourability scores were computed in a second stage using algorithms based on statistical/probabilistic analyses (Information Value Method), over unique terrain conditions, in a raster basis. Terrain attributes derived from the Digital Terrain Model (DTM) were used as proxies to several driving factors of MTDs, and as predictors in the models. As a result, three models are discussed independently in this paper according to the different datasets used to interpret MTDs (Models 1, 2 and 3). The results were prepared by sorting all pixels according their favourability value, in descending order, and the robustness and accuracy of the MTD favourability models were evaluated by success-rate curves. The curves aided the quantitative interpretation of the models expressing their goodness of fit to the interpreted MTDs. This work is important because the outputs resulting from the methodology confirm that this new method can be applied to submarine slopes. From the three models, Model 3 obtained the highest goodness of fit (0.862). Based on our results, a sensitivity analysis was undertaken and key predisposing factors were identified. This new methodology has the potential to become a very important and valid approach for the recognition of submarine slopes prone to failure on continental margins around the world

Eventos hidrogeomorfológicos em Portugal e a sua associação com os "weather types"

In recent years it has been possible to improve the characterization of past floods and landslides that caused human and economic impact in Portugal for the 1865-2015 period. In this regard there is an urge for a more systematic assessment of the atmospheric circulation at the synoptic scale associated to flood and landslide damaging events to correctly characterize the climatic forcing of hydro-geomorphologic risk in Portugal. Here we provide a comprehensive analysis of the atmospheric circulation based on the weather type classification, an automated version of the Lamb weather type procedure, initially developed for the United Kingdom and often named circulation weather types (CWT) and latter adapted for Portugal.info:eu-repo/semantics/publishedVersio

Efeitos da delimitação da área de estudo nos resultados da avaliação da suscetibilidade à rotura de movimentos de vertente com recurso a métodos estatísticos

Com este estudo pretende-se avaliar os efeitos da delimitação da área de estudo nos resultados de avaliação da suscetibilidade a fenómenos de instabilidade geomorfológica. A avaliação da suscetibilidade foi efetuada através do método estatístico do Valor Informativo. Para tal foi utilizado um inventário de 442 deslizamentos translacionais superficiais, desencadeados por episódios de precipitação, e 9 fatores de predisposição. Numa primeira fase foi elaborado um modelo de suscetibilidade para a totalidade de uma bacia hidrográfica da Ribeira Grande (ilha de São Miguel, Açores) (Modelo A). Numa segunda fase, o mesmo método estatístico foi aplicado a uma área mais restrita, correspondente ao sector montante da bacia hidrográfica, onde se concentra a maioria dos movimentos de vertente (Modelo B). Os resultados obtidos indicam que o Modelo B, apesar de registar taxas de sucesso e de predição mais baixas, é mais realista e reflete melhor a real capacidade estatística para antecipar a localização espacial de futuros deslizamentos.info:eu-repo/semantics/publishedVersio

Technical Note : assessing predictive capacity and conditional independence of landslide predisposing factors for shallow landslide susceptibility models

The aim of this study is to identify the landslide predisposing factors' combination using a bivariate statistical model that best predicts landslide susceptibility. The best model is one that has simultaneously good performance in terms of suitability and predictive power and has been developed using variables that are conditionally independent. The study area is the Santa Marta de Penaguião council (70 km2) located in the Northern Portugal. In order to identify the best combination of landslide predisposing factors, all possible combinations using up to seven predisposing factors were performed, which resulted in 120 predictions that were assessed with a landside inventory containing 767 shallow translational slides. The best landslide susceptibility model was selected according to the model degree of fitness and on the basis of a conditional independence criterion. The best model was developed with only three landslide predisposing factors (slope angle, inverse wetness index, and land use) and was compared with a model developed using all seven landslide predisposing factors. Results showed that it is possible to produce a reliable landslide susceptibility model using fewer landslide predisposing factors, which contributes towards higher conditional independence

Guia metodológico para a produção de cartografia municipal de risco e para a criação de sistemas de informação geográfica (SIG) de base municipal

A identificação, a caracterização e a avaliação metódica dos riscos naturais, tecnológicos e mistos que condicionam a segurança das comunidades são passos fundamentais no adequado desenvolvimento dos procedimentos de planeamento de emergência e de ordenamento do território. No período em que os processos de revisão dos Planos Directores Municipais e dos Planos Municipais de Emergência estão a ser promovidos pelos vários municípios, torna-se oportuna a existência de uma orientação metodológica para a elaboração da cartografia de risco que uniformize os procedimentos a adoptar neste contexto e introduza novas regras de harmonização decorrentes da transposição de directivas comunitárias para o quadro legal interno. O Despacho n.º 27660/2008, de 29 de Outubro de 2008, dos Secretários de Estado da Protecção Civil e do Ordenamento do Território e das Cidades, constituiu o grupo de trabalho que teve por missão elaborar um guia metodológico para a produção de cartografia municipal de risco e para a criação de sistemas de informação geográfica (SIG) de base municipal. Este guia permite aos municípios disporem de uma base metodológica comum para promoverem a identificação e a selecção dos riscos naturais, tecnológicos e mistos significativos, para produzirem a cartografia de risco temática de âmbito municipal de forma harmonizada e para construírem os SIG de base municipal, no que respeita a levantamento, monitorização e validação dos dados sobre os riscos. No entanto, o guia metodológico não deve ser utilizado de forma acrítica, necessitando obrigatoriamente do seu ajustamento à realidade municipal e aos objectivos tidos por prioritários em termos de planeamento de emergência e de ordenamento do território. O guia constitui uma base de trabalho multidisciplinar para os técnicos da cartografia e SIG e os das áreas temáticas abordadas. Importa ainda reforçar a ideia de que se deve valorizar a cooperação intermunicipal e regional, designadamente para a abordagem das componentes de risco que extravasam claramente a lógica concelhia. O presente Guia é constituído por um corpo principal, no qual, após um breve enquadramento inicial (capítulo 1), se definem os conceitos fundamentais a aplicar (capítulo 2), se identifica o conjunto global de riscos a partir do qual se fará a selecção dos riscos a cartografar em cada município (capítulo 3) e se explicitam os procedimentos a adoptar para a produção da cartografia municipal de risco (capítulo 4). O último capítulo do guia estabelece as linhas de orientação para a criação dos SIG associados a esta temática (capítulo 5). Nos dois anexos apresentam-se os aspectos metodológicos específicos para a produção das principais peças cartográficas (Cartas de Susceptibilidade e Cartografia de Elementos Estratégicos, Vitais e/ou Sensíveis). Salienta-se por fim que este Guia deverá sofrer as necessárias adaptações para a sua aplicação nos territórios das Regiões Autónomas dos Açores e da Madeira.info:eu-repo/semantics/publishedVersio