Floods in southern Portugal: their physical and human causes, impacts and human response

Floods have been the most deadly natural disasters in Portugal during the last century, followed by earthquakes. The type of flood known as a ‘progressive flood’ mainly affects the larger basins, such as that of the Tagus River, and results in a large inundated area. These floods are caused by heavy rains associated with a westerly zonal circulation that may persist for weeks. The system of dams within the basin reduces the frequency of flooding, but cannot ‘tame’ the river. The dam system has even contributed to an increase in the peak flow, as in the 1979 flood. Nevertheless, these floods are not a danger for the human population. In contrast, flash floods are more dangerous and deadlier than progressive floods, as demonstrated in 1967 and 1997. They affect the small drainage basins and are caused by heavy and concentrated rainfall, created by convective depressions (active cold pools or depressions caused by the interaction between polar and tropical air masses), active in the south of the country, in the Lisbon region, Alentejo and the Algarve. Deforestation, soil impermeability, chaotic urbanization, building on floodplains, the blockage of small creeks or their canalisation, and the building of walls and transverse embankments along the small creeks all contribute to the aggravation of this kind of flood.info:eu-repo/semantics/publishedVersio

Post-wildfires effects on physicochemical properties of surface water: the case study of Zêzere watershed (Portugal)

In Portugal, wildfires are frequent and sometimes catastrophic and responsible for high damages and human losses. They have been especially intense in the Center Region of Portugal, where the Zêzere watershed is located. This research presents an analysis of the temporal and spatial occurrence of these events within the watershed. It was observed that the extent of the burned areas has a high annual variation and is not directly related to the number of reported occurrences. However, considering these factors and the high incidence of these events in some delimited sectors, environmental stress is observed, especially on the surface water quality. Water quality deterioration in the main water bodies is particularly relevant within the areas where drinking water reservoirs are located. The water quality parameters (WQPs) collected by the water quality monitoring stations (WQSs) located in these sectors (data from SNIRH) were cross-referenced with the burned areas recorded annually. Variations in the physicochemical properties of the surface water were analyzed, depending on the occurrence of wildfires and their corresponding burned areas. The increase of certain WQP downstream of watercourses that intersect sub-basins with burned areas also demonstrates the straight relation between wildfires and an increasing risk for water quality.info:eu-repo/semantics/publishedVersio

SoResilere—A Social Resilience Index Applied to Portuguese Flood Disaster-Affected Municipalities

Decades of academic discussion on social resilience have led to the development of indicators, indexes, and different approaches to assessing it at national and local levels. The need to show real-world applications of such assessments is evident since resilience became a political and disaster risk reduction governance component. This article gives a full description of the methodology used to develop SoResilere, a new social resilience index applied to flood disaster-affected Portuguese municipalities. Study cases were selected according to historical databases, academic sources and governmental entities. Statistical methods for data dimension reduction, such as Factor Analysis (through Principal Component Analysis), were applied to the quantitative data and Optimal Scaling to the categorical data. SoResilere results were analyzed. Since SoResilere is a new tool, component weighting was applied to compare results with no weighting, although it did not affect the SoResilere status in 55.5% of the study cases. There is a tendency to look at the improvement of SoResilere results with component weighting due mainly to the quantitative subindex. There is no evidence of the benefits of component weighting, as no logical association or spatial pattern was found to support SoResilere status improvement in 22.22% of the study cases.info:eu-repo/semantics/publishedVersio

Avaliação da suscetibilidade de ocorrência de deslizamentos na bacia hidrográfica do Zêzere: a importância das propriedades da geoinformação

Alguns deslizamentos na bacia hidrográfica do Zêzere (5063,9 km2) têm provocado prejuízos materiais, sobressaindo a destruição ou interrupção de estradas que causaram constrangimentos socioeconómicos. A suscetibilidade de ocorrência de deslizamentos tem sido avaliada em diferentes contextos, sendo os fatores de predisposição considerados na modelação provenientes de diferentes conjuntos de geoinformação que é por vezes escolhida de forma aleatória, i.e., não se justifica a escolha de determinado conjunto de geoinformação em detrimento de outro com diferentes propriedades. Neste contexto destaca-se a geoinformação do uso e ocupação do solo (em inglês “land use and land cover” - LUC). O principal objetivo desta investigação é a determinação da suscetibilidade de ocorrer deslizamentos na bacia hidrográfica do Zêzere com dois conjuntos de geoinformação LUC com diferentes propriedades (Tabela 1), para se perceber se há variação dos resultados finais de suscetibilidade.info:eu-repo/semantics/publishedVersio

Understanding driving forces and implications associated with the land use and land cover changes in Portugal

Understanding the processes of land use and land cover changes (LUCC) and the associated driving forces is important for achieving sustainable development. This paper presents the LUCC in Portugal at the regional level (NUTS II) from 1995 to 2010 and discusses the main driving forces and implications associated with these LUCC. The main objectives of this work are: (a) to quantify the land use and land cover (LUC) types (level I of LUC cartography) by NUT II in Portugal for the years 1995, 2007 and 2010; (b) to assess the spatio-temporal LUCC; and (c) to identify and discuss the main driving forces of LUCC and corresponding implications based on correlations and Principal Components Analysis. The results revealed large regional and temporal LUCC and further highlighted the different and sometimes opposite time trends between neighboring regions. By associating driving forces to LUCC, different influences at the regional level were observed, namely LUCC into agriculture land derived from the construction of dams (Alentejo region), or the conversion of coniferous forest into eucalypt forest (Centre region) associated with increased gross value added (GVA) and employment in industry and forestry. Temporal differentiation was also observed, particularly in the settlements that expanded between 1995 and 2007 due to the construction of large infrastructures (e.g., highways, industrial complexes, or buildings), which is reflected on employment in industry and construction and respective GVA. However, certain LUCC have implications, particularly in energy consumption, for which different behavior between regions can be highlighted in this analysis, but also on land-use sustainability.info:eu-repo/semantics/publishedVersio

The floods in the south of Portugal in different kinds of drainage basins

No século XX, as cheias foram o desastre natural mais mortífero em Portugal, seguidas pelos sismos: por cada morte devida aos sismos morreram sete pessoas devido às cheias. O tipo de cheias conhecidas como «cheias progressivas» afectam principalmente as grandes bacias hidrográficas, como a do rio Tejo, provocando a inundação de uma ampla área. Este tipo de cheias é causado por períodos de chuva abundante relacionada com a circulação zonal de oeste que se mantém durante semanas. O sistema de barragens da bacia reduz a frequência das cheias mas não consegue «domar» o rio, contribuindo mesmo, por vezes, para o aumento do pico de escoamento, tal como aconteceu em 1979. Apesar disso, estas cheias não constituem, geralmente, um perigo para a população. As cheias rápidas, pelo contrário, são perigosas e mortíferas, tais como as que ocorreram em 1967, 1983 e 1997. Afectam as pequenas bacias de drenagem e são causadas por chuvadas fortes e concentradas, devido a depressões convectivas (gotas frias extremamente activas ou depressões estacionárias causadas pela interacção entre as circulações polar e tropical), nomeadamente no Sul do País (região de Lisboa, Alentejo e Algarve). A desflorestação, a impermeabilização dos solos, a urbanização caótica, a construção em leitos de cheia, o entulhamento dos pequenos cursos de água, ou a sua canalização, a construção de muros e aterros transversais ao sentido de escoamento das linhas de água, que funcionam como diques, contribuem para a agravamento deste tipo de cheias. São aqui analisadas as cheias nos rios do Sul do País, desde as grandes bacias de drenagem (rio Tejo, 80 100 km2 ) até às mais pequenas (ribeira de Cobres, 700 km2 ; ribeira da Garganta, 1 km2 ).The regime of the Portuguese rivers depends on the space and time variation of rainfall. Portugal has clear regional contrasts in the geographical distribution of rainfall. The NW and the Central Mountain Range (Cordilheira Central) are the regions with more rainfall. The NE and the south are the driest regions. The rainfall regime is very irregular. The monthly rainfall regime is clearly Mediterranean with autumn-winter rains (November-March) and an extremely dry summer. The river flows are also very irregular, with severe droughts and surprisingly high flood discharges. These characteristics tend to worsen from NW to SE. The southern rivers have specific discharges 6 to 7 times inferior to the ones of the NW, greater irregularity (the flow in years with more rainfall may surpass 100 to 240 times the flow in driest years), a more severe drought (6 months), almost all are temporary, and flood peaks (200-300 times the average flow) can reach extremely high values. In the twentieth century, floods were responsible for the highest rate of casualties in natural disasters in Portugal, followed by earthquakes: one death for every seven were due to floods. The type of floods known as «progressive floods» mainly affects the big hydrographic basins, such as the River Tagus basin, due to the large flooded area. This kind of flood is caused by heavy rainfall periods connected to the western zonal circulation, which usually lasts several weeks. The dams’ basin system reduces flood frequency, especially in autumn when reservoirs still manage to absorb the high flows after the summer dry period, but cannot «tame» the river. It has even contributed to an increase of the peak flow, as in the 1979 flood. Flashfloods are another kind of floods that occur in Portugal and, unlike the former, are dangerous and deadly, such as those in 1967, 1983 and 1997. They affect the small drainage basins and are caused by heavy and concentrated rainfalls, due to convective depressions (cold pools especially active or depressions caused by the interaction between polar and tropical circulations), namely in the south of the country (Lisbon region, Alentejo and Algarve). In the small drainage basins with a natural regime (uninfluenced by a dam), it is interesting to verify the existence of a trend in these extreme phenomena over the last decades. There has been a clear intensification of flood importance during autumn months, in contrast with an accentuated diminishing in winter and spring months. This trend concerns us mainly for two reasons. Firstly, the rainfall concentration in fewer months lessens its availability in the other months and requires a greater storage capacity. Secondly, this concentration means a bigger rainfall intensity in autumn, with the worsening of the number and intensity of floods and a greater soil loss. Deforestation, soil impermeability, chaotic urbanisation, building on floodplains, the blocking up of small creeks, or their canalisation, the building of walls and transverse embankments along the small creeks courses that work as dikes, contribute to the aggravation of this kind of floods. The floods in rivers of southern Portugal are here analysed, and range from the big drainage basins (River Tagus, 80 100km2 ), to the smaller ones (Cobres stream, 700 km2 ; Garganta stream, 1 km2 ). Also discussed are the human causes that have contributed to increasing the consequences of the floods in small catchments.info:eu-repo/semantics/publishedVersio

Introductory Chapter: How to Use Design of Experiments Methodology to Get Most from Chemical Processes

Economic pressure and the need to target more competitive levels drive organizations to invest in efficient methodologies to get solutions able to provide clear advantages in a very demanding market. In this scenario, statistical approaches emerge as valuable tools to be used in the chemical process industry. Indeed, the chemical industry uses a wide set of statistical methodologies, ranging from descriptive approaches to complex optimization topics such as Design of Experiments (DoE), always targeting safer, more repeatable and profitable solutions.info:eu-repo/semantics/publishedVersio

Development of a stream flood susceptibility index at the municipal level in mainland Portugal

The 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.info:eu-repo/semantics/publishedVersio

Physical vulnerability assessment to flash floods using an indicator‐based methodology based on building properties and flow parameters

This study focuses on the physical vulnerability of buildings to flash floods using an indicator-based methodology. A physical vulnerability index (PhVI) that combines intrinsic vulnerability (IV) of buildings and flash flood intensity (FFI) is proposed. IV evaluates the propensity to suffer damage, resulting from indicators related to building properties. FFI estimates the potential to cause damage, resulting from indicators related to flow parameters. PhVI was applied to a critical section of a small drainage basin in Portugal where flash floods are frequent. Evaluating IV and the intensity of natural hazards is essential in physical vulnerability assessments. This study addresses two problems found in the literature: the lack of flash flood-dedicated physical vulnerability assessments and the difficulties in assembling building properties and the intensity of natural hazards in a vulnerability index defined from indicatorbased methodologies. PhVI is a useful tool where damage records are rare or non-existent, allowing the prioritisation of resources and application of local protection measures. This index can be adapted to other study areas and natural hazards, although more research is needed to improve the knowledge on the indicators and weights of IV and FFI.info:eu-repo/semantics/publishedVersio