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- Landslide susceptibility assessment using different rainfall event-based landslide inventories: advantages and limitationsPublication . Oliveira, Sérgio; Zêzere, José; Garcia, Ricardo; Pereira, Susana; Vaz, Teresa; Melo, RaquelThe present work aims to evaluate potential sources of uncertainty associated with rainfalltriggered event-based landslide inventories within the framework of landslide susceptibility assessment. Therefore, this study addresses the following questions: (i) How representative is an event-based landslide inventory map of the total landslide activity and distribution in a study area?; (ii) How reliable is an event-based landslide susceptibility map?; (iii) How appropriate is an event-based landslide inventory map for independently validating a landslide susceptibility map? To address these questions, two independent and contrasting rainfall event-based landslide inventories were used, together with a historical landslide inventory, to assess landslide susceptibility for diferent types of landslides in a study area located north of Lisbon, Portugal. The results revealed the following fndings: (i) contrasting rainfall critical conditions for failure can trigger similar landslide types, although they may vary in size and be spatially constrained by diferent predisposing conditions, particularly lithology and soil type; (ii) landslide susceptibility models using event-based landslide inventories are not reliable in the study area, regardless of the landslide inventory map used for training and validation; and (iii) complementary sources of uncertainty results from using incomplete historical landslide inventories to assess landslide susceptibility and non-totally independent landslide inventories for modeling validation. The present study enhances the understanding of regional landslide susceptibility patterns based on contrasting rainfall-trigger conditions, providing valuable information to minimize exposure; to design regional landslide early warning systems for specifc rainfall-trigger landslide events; and to improve the response and preparedness of civil protection services.
- Uncertainty into statistical landslide susceptibility models resulting from terrain mapping units and landslide input dataPublication . Zêzere, José Luís; Pereira, Susana; Melo, Raquel; Oliveira, Sérgio; Garcia, Ricardo A C
- On the Multi-hazard Risk Assessment of Urban Areas: Identification and Analysis of Exposure and Physical Vulnerability IndicatorsPublication . Xofi, Maria; Domingues, José Carlos; Santos, Pedro Pinto; Pereira, Susana; Oliveira, Sérgio; Reis, Eusébio; Zêzere, José; Garcia, Ricardo; Lourenço, Paulo B.; Ferreira, Tiago MiguelThe development of integrated decision-support tools, able to assess multiple hazards at the regional and local scales, is a fundamental step to enhance the preparedness of urban areas to mitigate present and future risks arising from climate change. Understanding multi-hazard risk can help prioritize resilience-increasing actions and disaster prevention measures and form the basis for exploring institutional adjustments that improve stakeholders’ capacities to manage risk. Within this framework, the present research work aims to identify and analyze a set of exposure and buildings’ vulnerability indicators to be used as input to a multi-hazard risk assessment methodology. Exposure is to be measured using a dimensionless score resulting from the quantitative identification of the elements at risk. Regarding the physical vulnerability of buildings, it is to be evaluated on a hazard-by-hazard basis using a large-scale parametric-based vulnerability assessment approach. Finally, the obtained exposure and physical vulnerability indicators are to be put together in order to create different data layers, which are then used to identify hotspot risk areas. The Metropolitan Area of Lisbon, Portugal, is used as a pilot study area to discuss the applicability and potential of the proposed indicators.
- Perfis municipais de risco a cheias e inundações para aplicação ao ordenamento do território em Portugal continentalPublication . Pereira, Susana; Santos, Pedro Pinto; Zêzere, José; Reis, Eusébio; Santos, Mónica; Garcia, Ricardo A C; Oliveira, Sérgio; Rocha, Jorge; Fragoso, Marcelo; Vaz, Teresa; Meneses, Bruno; Rilo, Ana; Bateira, Carlos
- Perfis municipais de risco de instabilidade de vertentesPublication . Pereira, Susana; Santos, Pedro Pinto; Zêzere, José; Tavares, Alexandre Oliveira; Reis, Eusébio; Garcia, Ricardo A C; Oliveira, Sérgio
- Integration of landslide susceptibility maps for land use planning and civil protection emergency managementPublication . Oliveira, Sérgio; Zêzere, José; Guillard, Clemence; Garcia, Ricardo A C; Pereira, SusanaLandslides are one of the most relevant geomorphological hazards in Portugal, by the high levels of people affected, destruction of assets and disruption of economic and social activities. Regarding the Portuguese territorial land use planning and emergency management, regulation, practice, prevention and risk management have been promoted in different ways. In Portugal, the areas susceptible to landslides are included in the 'National Ecological Reserve', which is a public utility restriction legal figure that rules the land use planning at the municipal level. In addition, the Municipal Emergency Plans include landslide susceptibility maps that are combined with the map of the exposed elements, allowing the assessment of exposure to landslides. This study is applied to the Loures municipality located to the north of Lisbon. In this municipality 621 landslides registered in a landslide inventory (rotational slides, deep-seated translational slides and shallow translational slides) that affected 1,469,577 m2 (0.87 %) of the Loures territory. The final landslide susceptibility map shows that in Loures municipality 1,347 ha are associated to a Very high landslide susceptibility and 2,372 ha to High landslide susceptibility, which corresponds both to 22.1 % of the entire municipality, and constitutes the larger fraction of the National Ecological Reserve, related to landslides. These areas do not present geomorphological and geotechnical suitability for building structures or infrastructures. From the civil protection and emergency management point of views 34 classes of exposed elements were identified in the municipality, with point, linear and polygonal representations. The elements at risk located in the Very High or High landslide susceptibility classes were summarized and correspond to: high voltage poles; wind turbines; transmission/reception antennas; industrial areas; water tanks; silo; gas station/tank; service area; buildings of educational institutions; worship buildings; buildings of electricity facilities; regular buildings; gas pipeline; motorways; national roads; and municipal roads.
- Exposure and physical vulnerability indicators to assess seismic risk in urban areas: a step towards a multi-hazard risk analysisPublication . Xofi, Maria; Domingues, José Carlos; Santos, Pedro; Pereira, Susana; Oliveira, Sérgio; Reis, Eusébio; Zêzere, José; Garcia, Ricardo A. C.; Lourenço, Paulo B.; Ferreira, Tiago MiguelUnderstanding the impacts of multi-hazard risk in urban areas is a fundamental step towards the adoption of resilience-enhancement and disaster prevention strategies, underpinning institutional adjustments aimed at improving the capacity of the authorities and stakeholders to manage risk. Within this framework, the work presented in this paper seeks to identify and analyze a set of exposure and buildings’ physical vulnerability indicators to be used as input to a parametric-based seismic vulnerability assessment methodology for the unreinforced masonry (URM) building stock of Lisbon Metropolitan Area (LMA). For this approach, data from the 2011 Census survey are used to define the parameters describing the building’s physical vulnerability and characterise the level of exposure in the study area. These results are then combined with the hazard component into a GIS tool. Seismic vulnerability results are presented for the URM building stock in LMA, and a more detailed analysis is conducted for the building stock of Set ubal municipality. Finally, risk outputs are presented and briefly discussed. Ultimately, understanding the impact and extent of multi-hazards can help prioritize resilienceincreasing actions and disaster prevention measures to mitigate and manage natural hazards.
- Integration of landslide susceptibility maps for land use planning and civil protection emergency managementPublication . Oliveira, Sérgio C.; Zêzere, José; Guillard-Gonçalves, Clémence; Garcia, Ricardo A C; Pereira, SusanaLandslides are one of the most relevant geomorphological hazards in Portugal, by the high levels of people affected, destruction of assets and disruption of economic and social activities. Regarding the Portuguese territorial land use planning and emergency management, regulation, practice, prevention and risk management have been promoted in different ways. In Portugal, the areas susceptible to landslides are included in the ‘National Ecological Reserve’, which is a public utility restriction legal figure that rules the land use planning at the municipal level. In addition, the Municipal Emergency Plans include landslide susceptibility maps that are combined with the map of the exposed elements, allowing the assessment of exposure to landslides. This study is applied to the Loures municipality located to the north of Lisbon. In this municipality 621 landslides registered in a landslide inventory (rotational slides, deep-seated translational slides and shallow translational slides) that affected 1,469,577 m2 (0.87%) of the Loures territory. The final landslide susceptibility map shows that in Loures municipality 1347 ha are associated to a Very high landslide susceptibility and 2372 ha to High landslide susceptibility, which corresponds both to 22.1% of the entire municipality, and constitutes the larger fraction of the National Ecological Reserve, related to landslides. These areas do not presente geomorphological and geotechnical suitability for building structures or infrastructures. From the civil protection and emergency management point of views 34 classes of exposed elements were identified in the municipality, with point, linear and polygonal representations. The elements at risk located in the Very High or High landslide susceptibility classes were summarized and correspond to: high voltage poles; wind turbines; transmission/reception antennas; industrial areas; water tanks; silo; gas station/tank; servisse area; buildings of educational institutions; worship buildings; buildings of electricity facilities; regular buildings; gas pipeline; motorways; national roads; and municipal roads.
- Defining evacuation travel times and safety areas in a debris flow hazard scenarioPublication . Melo, Raquel; Zêzere, José; Oliveira, Sérgio; Garcia, Ricardo A C; Oliveira, Sandra; Pereira, Susana; Piedade, Aldina; Santos, Pedro Pinto; van Asch, TheoDebris flows are one of the most hazardous types of landslides in mountain regions. In the upper part of the Zêzere valley (Serra da Estrela, Portugal) several debris flows events occurred in the last 200 years, some of them causing loss of lives and material damages. In this work, a methodology for pedestrian evacuation modelling, in a debris flow hazard scenario, was implemented. A dynamic run-out model, developed in previous studies, was used to evaluate the debris flows velocities, thickness of the deposits and extent of the mobilized material. The buildings potentially affected by the impact of debris flows were identified and the potentially exposed population was estimated by applying a dasymetric distribution. The results lead to the conclusion that, in the study area, the elderly are those who are most exposed to debris flows. Furthermore, the time lapse between the debris flows initiation and the arrival at the buildings at risk was estimated, allowing to account for the overall number of buildings where the evacuation time takes longer than the debris flows arrival. Additionally, the safe areas within the study area were identified, and several safe public buildings with the capacity to gather a large number of persons were selected. Considering that the study area is located in a mountain region, characterized by steep slopes, the evacuation modelling was performed based on an anisotropic approach, in order to consider the influence of slope direction on travel costs. At the end, three pedestrian evacuation travel time scenarios, based on different walking speeds to accommodate residents with different ages in safer places, were compared and the results mapped. The implemented methodology is not local dependent, which allows its reproduction elsewhere.
- Avaliações multirrisco como abordagem para a construção de cidades resilientes e sustentáveisPublication . Santos, Pedro; Pereira, Susana; Lourenço, Paulo; Zêzere, José Luís; Reis, Eusébio; Oliveira, Sérgio; Garcia, Ricardo; Ferreira, Tiago MiguelO conhecimento integrado dos fatores de risco é um elemento-chave para o desenho e implementação de políticas, estratégias e medidas de redução de impactos. O presente trabalho procura contribuir para a definição de metodologias de avaliação do efeito combinado da manifestação de múltiplos fenómenos perigosos, tomando como exemplos os processos de inundação costeira, cheias, sismos, movimentos de massa em vertentes e incêndios urbanos, e como área de trabalho os 18 municípios da Área Metropolitana de Lisboa. A avaliação de risco considera os fatores de suscetibilidade/perigosidade, exposição e vulnerabilidade. Os resultados obtidos até ao momento identificaram os pares de fenómenos perigosos cujo efeito combinado se traduz nos cenários de risco mais elevado, com destaque para a relação entre sismicidade e incêndios urbanos.