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- Flood susceptibility assessment based on Analytical Hierarchy Process: application in mainland PortugalPublication . Santos, Pedro Pinto; Pereira, Susana; Zêzere, José; Reis, Eusébio; Garcia, Ricardo A C; Oliveira, Sérgio; Santos, MónicaAlthough the scientific and computational advances in the hydrological study of flood hazard assessment, a demand still exists concerning more expedite and extensive methods to map flood susceptibility or proneness over large areas. The relevant question is very often to achieve the best equilibrium between the complexity of flood hazard models and the accuracy and quantity of the input data. The presented study aims to assess flood susceptibility in mainland Portugal through the application of an Analytical Hierarchy Process (AHP), using 17 flood susceptibility conditioning factors related with: i) terrain morphology (elevation, slope angle, slope over area ratio, flow accumulation, topographic position index, landform classification - Jenness); ii) basin morphology (hypsometric integral, Gravelius index, circularity ratio and the orographic coefficient of Fournier); iii) permeability (lithology, , alluvial zones, hydraulic conductivity and ecological zones); iv) rainfall (water balance) and v) hydrography (drainage density and Strahler’s fluvial hierarchy). All variables were classified according to empirical knowledge and further defined as raster datasets at the national level with a resolution of 25x25 m cell size. AHP technique was used to achieve the relative weights based on the Saaty’s scale of influence, which ranges between 1 and 9. The weighting of conditioning factors was performed at two levels: initially, between variables and, secondly, between the different classes of each variable. This later process, although consensual regarding most of the variables (e.g., slope angle or flow accumulation) is rather more complex regarding specific variables which require a deeper interpretation of scores (e.g., topographic position index, landform classification and the permeability-related variables). The study also highlights the challenges posed during the data preparation and integration steps, namely, the integration of data from variables that are represented at the basin level (e.g., those related to basin morphometry and hydrologic behavior) with data represented on a cell-by-cell basis, such as flow accumulation or slope angle. Future exploration of the results includes the aggregation of the AHP-based flood susceptibility scores – distinguishing progressive floods from flash floods – at the administrative level, achieving a flood susceptibility municipal index in order to verify to each extend disastrous floods have been controlled by natural constrains at the municipal level. Such indexes will be applied later in decision support systems in order to define public civil protection-related resources.
- Avaliação da suscetibilidade das linhas de água a cheias utilizando análise multicritérioPublication . Santos, Pedro Pinto; Pereira, Susana; Reis, Eusébio; Santos, Mónica
- A Novel Approach to Measuring Spatiotemporal Changes in Social Vulnerability at the Local Level in PortugalPublication . Santos, Pedro Pinto; Zêzere, José; Pereira, Susana; Rocha, Jorge; Tavares, Alexandre OliveiraSocial vulnerability, as one of the risk components, partially explains the magnitude of the impacts observed after a disaster. In this study, a spatiotemporally comparable assessment of social vulnerability and its drivers was conducted in Portugal, at the civil parish level, for three census frames. The first challenging step consisted of the selection of meaningful and consistent variables over time. Data were normalized using the Adjusted Mazziotta-Pareto Index (AMPI) to obtain comparable adimensional-normalized values. A joint principal component analysis (PCA) was applied, resulting in a robust set of variables, interpretable from the point of view of their self-grouping around vulnerability drivers. A separate PCA for each census was also conducted, which proved to be useful in analyzing changes in the composition and type of drivers, although only the joint PCA allows the monitoring of spatiotemporal changes in social vulnerability scores and drivers from 1991 to 2011. A general improvement in social vulnerability was observed for Portugal. The two main drivers are the economic condition (PC1), and aging and depopulation (PC2). The remaining drivers highlighted are uprooting and internal mobility, and daily commuting. Census data proved their value in the territorial, social, and demographic characterization of the country, to support medium- and long-term disaster risk reduction measures.
- Landslide risk profiles for municipal land use planning in PortugalPublication . Pereira, Susana; Santos, Pedro Pinto; Zêzere, José; Tavares, Alexandre Oliveira
- Development of a stream flood susceptibility index at the municipal level in mainland PortugalPublication . Santos, Pedro Pinto; Reis, Eusébio; Pereira, Susana; Santos, MónicaThe growing computational capabilities and data availability promotes the development of flood susceptibility methodologies, although there is still field for improvement regarding small-scale flood susceptibility assessment. In this research, after assessing a national stream flood susceptibility (SFS) on a cell-by-cell basis, a municipal representation of SFS was performed to rank the 278 municipalities in mainland Portugal.