ISEP – DMA – Comunicações em eventos científicos
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- Fatores e processos em ravinas permanentes em ambiente mediterrâneo (Centro de Portugal)Publication . Martins, Bruno; Nunes, Adélia; Meira Castro, Ana C.; Lourenço, LucianoNa bacia do rio Alva, à semelhança de outras áreas serranas do nosso território, algumas ravinas atingem uma dimensão espetacular. Neste trabalho procuramos analisar alguns fatores responsáveis pela evolução da ravina do Corgo, localizada no vale do rio Alva, no Centro de Portugal, nos últimos 4 anos (2015-2019), considerando o declive, a percentagem de coberto vegetal, a resistência do solo à penetração e torção, e a forma da vertente. Para o efeito, aplicou-se modelo de regressão múltipla (stepwise), ferramenta usada na construção de modelos para identificar um subconjunto útil de preditores. No período em análise, a ravina, com um comprimento de 130 metros, localizada sobre um manto de alteração granítico, teve um alargamento médio de 27.8 cm (DP: 72.0 cm) e um aprofundamento médio de 66 cm (DP: 85.5cm). Na evolução da ravina, o modelo de regressão explica entre 26% e 45 % do seu alargamento. Os resultados indicam 26% da variabilidade pela resistência do solo à penetração; 35,4% quando à variável anterior se associa o declive; e 44,5% quando se considera também a forma da vertente. Por sua vez, o aprofundamento assinalado pela ravina é explicado, entre 26% e 44,5%, a partir do mesmo modelo de regressão. A forma da vertente explica 32% da variância observada. Quando, além desta variável, se considera a percentagem de coberto vegetal, o resultado aumenta cerca de 10%. O modelo com o melhor resultado, 44,5%, considera as variáveis: forma da vertente, percentagem do coberto vegetal e resistência do solo à penetração. Confirmando os fatores envolvidos na evolução da ravina e optimizando a ligação estatística entre os fatores e a evolução, os resultados podem fornecer informações importantes para prever taxas de erosão em ambientes semelhantes.
- Ravinas de Seirós (Norte de portugal). Simulação com vista a prevenir o seu reaparecimentoPublication . Martins, Bruno; Meira Castro, Ana C.; Ferreira, Carmen; Lourenço, Luciano; Nunes, AdéliaNeste trabalho são analisadas as ravinas de Seirós, localizadas próximo de Ribeira de Pena, no Norte de Portugal, e que, numa área agrícola, se instalaram sobre um coluvião. As ravinas formaram-se após um episódio de chuva intensa e concentrada, entre os dias 14 e 15 de dezembro de 2015. Este episódio chuvoso permitiu o galgamento de um canal, de geometria retangular, com cerca de 49 metros de comprimento, 0,70 metros de largura e 0,75 metros de profundidade, construído pelo proprietário do terreno agrícola como forma de proteção da escorrência proveniente de montante. Para além da caracterização e a análise dos factores que estiveram na génese das ravinas, este estudo também pretende discutir a adequação desta estratégia como forma de prevenção e mitigação do risco de ravinamento. Com base nos resultados obtidos pela simulação apresentada, torna-se claro que, para episódios de precipitação semelhantes o canal não é eficaz. Como medida mitigadora, sugere-se o aumento da profundidade da secção transversal do canal, cuja altura mínima recomendada deverá ser de 120 cm.
- The development of gullies in a Mediterranean environment: The example of the Corgo gully (central Portugal)Publication . Martins, B.; Meira Castro, Ana C.; Nunes, A.; Lourenço, L.Gullies are the most energy-efficient way to transport excess runoff from the watershed after a landscape disturbance. The diversity of physical factors that are associated with gully formation makes straightforward interpretation difficult and requires well-founded analysis based on local observations. Some gullies have developed in the Alva river basin and some of them reach a spectacular size, especially in areas where forest fires have recurred with greater severity. In this paper, we identify the most important factors in the formation and development of the River Corgo’s gully, located in the Alva river valley in central Portugal. The evolution of this gully in the last 4 years is also examined, based on a study of the modification of its morphological characteristics. The analysis was based on the Spearman-Rho correlation coefficient and stepwise multiple regression to estimate the correlation between the quantitative characteristics, geomorphological processes and biophysical variables. The results show that the main factors that seem to control the spatial variation of soil erosion are the soil penetration resistance, slope, slope shape and vegetation cover.
- Mortar with pet—Preliminary resultsPublication . Oliveira, Rosário; Garcia, Maria da Luz; Meira Castro, Ana C.; Silva, Teresa NetoThe objective of this work is to evaluate the performance and feasibility of the use of coating mortars with the incorporation of ground polyethylene terephthalate (PET) waste. It was studied the performance of 1: 4 mortars in weight with partial replacement of the aggregate by PET residuals in different percentages (0%, 5% and 10%). Obtained results showed a decrease of the mechanical resistance of mortars in the inverse proportion of the use of PET residues of the mixture, an increase in resistance to water absorption by capillary action and a decrease in thermal conductivity. These results support the potential use of PET waste in coating mortars, thereby contributing to reduce the environmental impact caused by plastic waste. However, in order to be considered energy efficient, this new material needs further improvements.
- Ravinas de Seirós (norte de Portugal). Simulação com vista a prevenir o seu reaparecimentoPublication . Martins, Bruno; Meira Castro, Ana C.; Ferreira, Carmen; Lourenço, Luciano; Nunes, AdéliaNeste trabalho são analisadas as ravinas de Seirós, localizadas próximo de Ribeira de Pena, no Norte de Portugal, e que, numa área agrícola, se instalaram sobre um coluvião. As ravinas formaram-se após um episódio de chuva intensa e concentrada, entre os dias 14 e 15 de dezembro de 2015. Este episódio chuvoso permitiu o galgamento de um canal, de geometria retangular, com cerca de 49 metros de comprimento, 0,70 metros de largura e 0,75 metros de profundidade, construído pelo proprietário do terreno agrícola como forma de proteção da escorrência proveniente de montante. Para além da caracterização e a análise dos factores que estiveram na génese das ravinas, este estudo também pretende discutir a adequação desta estratégia como forma de prevenção e mitigação do risco de ravinamento. Com base nos resultados obtidos pela simulação apresentada, torna-se claro que, para episódios de precipitação semelhantes o canal não é eficaz. Como medida mitigadora, sugere-se o aumento da profundidade da secção transversal do canal, cuja altura mínima recomendada deverá ser de 120 cm.
- Wildfires in Portugal: where and why?Publication . Nunes, Adélia; Meira Castro, Ana C.; Lourenço, Luciano; Martins, BrunoFire has been a key tool used by humans for several thousands of years and a vital component in ecosystem dynamics. Uncontrolled fires cause, however, large environmental and economic damages, especially in the Mediterranean region. Nowadays, wildfires rank top of all European forest problems, affecting landscape, wildlife, vegetation, soils, water and air quality, as well as the human wellbeing Portugal has the highest relative burnt area of all southern European countries, between 1980 and 2017. Therefore, several studies have been addressed to the drivers behind wildfires in Portuguese territory, linking them mainly with climate/weather conditions and changes in the landscape mosaic, as a consequence of agricultural abandonment and a marked increase in land covered by shrubs, grass and other light vegetation that is very prone to fire. The association between social and economic vulnerability and wildfire incidence, particularly in terms of burnt area, has received less attention. Based on the assumption that the association between burnt area incidence and socio-economic vulnerability varied geographically, the main goals of this study are: to analyse the spatial patterns of burnt area on a municipal level; to identify the most critical social and economic variables associated with spatial incidence and recurrence of wildfires, by comparing the performance of classical linear regression and geographically weighted regression (GWR) modelling; to map spatial variation in the relationships between social and economic vulnerability and wildfire incidence in order to identify spatial clusters. The results obtained clearly show a strong spatial association between the incidence of burnt areas and some socio-economic variables that contribute to wildfire vulnerability in mainland Portugal. In general, the results demonstrated that the municipalities with high burnt areas displayed high social and economic vulnerability as a result of the higher ageing index and unemployment rates. Conversely, higher income populations and the prevalence of higher livestock densities, namely sheep and goats, influence negatively on the burnt extension. The overlap between socio-economic vulnerability, in terms of low socio-economic status of residents, and wildfire incidence in Portuguese territory suggests a need to evaluate wildfire management policies with regard to social and economic conditions.
- O risco de ravinamento: o exemplo das ravinas de Seirós (norte de Portugal)Publication . Martins, Bruno; Meira Castro, Ana C.; Nunes, AdéliaNeste trabalho, é apresentado o exemplo de um conjunto de ravinas formadas numa área agrícola, sobre um coluvião, em Seirós, próximo de Ribeira de Pena, no Norte de Portugal. As ravinas formaram-se durante um episódio de chuva intensa e concentrada, em dezembro de 2015. A existência de um canal retangular de 49 metros de comprimento, 0,70 metros de largura e 0,75 metros de altura, construído pelo proprietário do terreno, como forma de proteção da escorrência a montante do terreno de cultivo, contribuiu para uma concentração excecional da escorrência que, sendo insuficiente para a conter, permitiu o transbordo e a consequente formação de 8 ravinas. A presença dessas ravinas impossibilitou a prática agrícola durante cerca de um ano, após o qual o proprietário, com recurso a maquinaria, não só neutralizou as ravinas, mas também procedeu à reconstrução do canal de proteção, parcialmente destruído durante o episódio chuvoso, tendo voltado a funcionar novamente como único meio de controlo de erosão. O estudo apresentado tem como objetivo a caracterização das ravinas, bem como, analisar os fatores determinantes na sua formação. Além disso, pretende-se ainda discutir a adequação da estratégia existente como forma de prevenção e mitigação do risco de ravinamento
- The influence of coal-fired power plants operations on environmental radioactivity and assessment of the associated radiation hazardPublication . Dinis, Maria de Lurdes; Fiúza, António; Góis, Joaquim; Carvalho, José S. de; Meira Castro, Ana C.The natural radioactivity of coal and by-products from coal-fired power plants has been reported in many countries. Most of these studies focus on the radioactivity levels of airborne discharges with enhanced concentration in fly ashes. However, the distribution of natural radionuclides in the environment is crucial to estimate the radiological impact and the resulting risk to the potential exposed nearby population. The activity released into the atmosphere from of a coal-fired power plants depends on many factors: the radionuclides concentration in coal, the ash content and inert matter of the coal, the combustion’s temperature, the portioning between bottom and fly ash and the efficiency of the filtering system. Therefore, marked differences should be expected between the by-products produced and the amount of activity discharged, per unit of energy produced, from different coal-fired power plants (Dinis et al., 2014). At national level, data from coal-fired power plants is not available as radionuclides measurements are not compulsory; regulations are only restricted to airborne discharges of SO2, NOx and suspended particles. The consequent radiological impact is rather difficult to estimate as there is no data concerning the radiological elements released. This study aims to evaluate the influence of a coal-fired power plant operation on the environmental radioactivity and the assessment of the resulting radiation hazard through the radium equivalent index (Raeq). The spatial distribution of the radionuclides found in the surroundings of a coal plant, and the hazard index, were investigated by statistic and geostatistics tools. The current study was applied to a coal plant located in the southwest coastline of Portugal. This power plant started working in 1985 with two operational stacks, both with 225 m height, and fuelled by bituminous coal. The main concern from this coal power plant results mainly from past atmospheric emissions. In fact, the amount of particulate matter released from this coal-fired power plant into the atmosphere decreased substantially in the last ten years: 1 740 tons (2001); 812 tons (2004); 587 tons (2007); 394 (2009); 130 tons (2010); 99.7 tons (2010); 286 (2011); 178 ton (2012) (E-PRTR, 2014).
- Identification and characterization of the main forest management systemsPublication . Lima, K. Sumaya; Meira Castro, Ana C.; Baptista, J. SantosA proficient forest management system aims to merge the sustainable use and exploitation of the forest with its conservation through a set of rules oriented towards the certification of forest management. In order to identify and characterize the main forest management systems available at the international level a scientific literature review was conducted in 24 databases. Two forest management systems internationally accepted were identified: the FSC system responsible for 39% of international forest management certifications and the PEFC system that accounts for 61%. Other forest management systems were also performed by some countries but their scope is strictly focused on the countries’ characteristics.
- Spatial patterns of forest fires ignition’ causes in mainland PortugalPublication . Meira Castro, Ana C.; Lourenço, Luciano; Sousa, António; Nunes, Adélia; Bento-Gonçalves, António; Vieira, AntónioThe spatial incidence of Mediterranean forest fire occurrences is inevitably linked to two main factors: the specificity of the environment, which includes the climatic and meteorological conditions of this region as well as the relief and the characteristics of the fuels, and the anthropic use of fire, mainly as a tool to control and modify the use of forest areas. Depending on the social, economic and cultural context of a given region, the causes of the forest fires ignition may spatially differ from country to country and from region to region within the same country. The fire ignition causes significantly influence the fire risk assessment. Thus, both the knowledge and the understanding of the motivations that are at the origin of forest fires are indispensable tools in the design of prevention policies, which must be adapted to the socio-economic, cultural and environmental reality of this country. In this communication, a description of the distribution of the number of forest fires whose causes were investigated, occurred in Portugal between 1996 and 2015, as well the correspondent burned area in this period is made. In addition, it is inspected how the causes of these investigated forest fires are related within the most critical years, as well as in those that were less problematic. The results of this investigation can be used to support an effective planning of fire mitigation and suppression as well an effective implementation of preventive policies of forest fire occurrences.