Browsing by Author "Fragoso, Rui"
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- A minimum cross entropy approach to disaggregate agricultural data at the field levelPublication . Xavier, Antonio; Fragoso, Rui; Costa Freitas, M. B.; Rosario, Maria do Socorro; Valente, FlorentinoAgricultural policies have impacts on land use, the economy, and the environment and their analysis requires disaggregated data at the local level with geographical references. Thus, this study proposes a model for disaggregating agricultural data, which develops a supervised classification of satellite images by using a survey and empirical knowledge. To ensure the consistency with multiple sources of information, a minimum cross-entropy process was used. The proposed model was applied using two supervised classification algorithms and a more informative set of biophysical information. The results were validated and analyzed by considering various sources of information, showing that an entropy approach combined with supervised classifications may provide a reliable data disaggregation.
- An approach using entropy and supervised classifications to disaggregate agricultural data at a local levelPublication . Xavier, Antonio; Fragoso, Rui; Costa Freitas, M. B.; Rosario, Maria do SocorroChanges in the Common Agricultural Policy (CAP) had several consequences on land-use and on the environment. This calls for detailed disaggregated agricultural data with precise geographical references. To tackle such problems data disaggregation processes are needed and a series of studies are being carried out at international level, which still have not taken the utmost advantage of remote sensing technologies by combining them with mathematical programming methods, namely entropy. Therefore, the objective of this article was to provide an approach to disaggregate agricultural data at the local level, taking advantage of the existent up-to-date satellite imagery and an entropy approach for manage different sets of data. The results were compared with other approaches and showed to be coherent, and may be improved further with the inclusion of other information.
- Analysing the recent dynamics of agricultural sustainability in Portugal using a compromise programming approachPublication . Xavier, António; Costa Freitas, M. B.; Fragoso, Rui; Rosário, Maria do SocorroSociety recognises the importance of agriculture to supply goods, which are essential for human survival and well-being. Sustainable agriculture is an important goal since resources need to be preserved for future generations. The recent agricultural policy orientations towards environmental concerns have also had consequences for Portuguese agriculture. The information provided by the 2019 Agricultural Census offers an opportunity to analyse the recent dynamics and establish rankings of municipalities related to agricultural sustainability. Sustainability in agriculture can be studied using different types of indicators, but its quantification and aggregation into an index is still difficult. This paper proposes an approach based on compromise programming to analyse sustainability considering the dynamics between the 2009 and 2019 Agricultural Census. This approach has three main steps: in the first one, the indicators are selected and a HJ-Biplot and Cluster analysis are carried out to identify groups of municipalities and general dynamics; in the second step, the weights of indicators are defined, and a novel compromise programming model is implemented to define the rankings of sustainability for each year; finally, in the third step, the spatial dynamics of the sustainability rankings are analysed and classified into the clusters of municipalities previously created. The analysis was implemented using data from the 308 Portuguese municipalities for 12 individual indicators encompassing the several dimensions of sustainability. The results were promising since the approach allowed for the identification of the main dynamics and tendencies regarding sustainability.
- A composite indicator to measure sustainable water use in Portugal: a compromise programming approachPublication . Costa Freitas, M. B.; Xavier, António; Fragoso, Rui; Antunes, CarlaClean water is an important resource for maintaining human life, economic activities, and ecosystems' survival. Nevertheless, its irregular distribution and occasional scarcity lead to the need to promote its sustainable use. To assess the current situation and the dynamics of sustainable water use, it is crucial to identify the main factors affecting it and to propose monitoring indicators. This paper develops an approach based on compromise programming to analyse water use sustainability at the municipal level, with a methodology that comprise a framework designed in five steps: 1 - indicators' choice; 2 - indicators's weights; 3 - definition of sustainability rankings with the application of a compromise programming approach; 4- application of a GIS analysis; 5 - identification of the main factors affecting sustainable water use. As a first result, the consensus weights of the chosen indicators were defined, indicating that the most important internal factors affecting sustainable water use are safe water, the percentage of housing served by water supply and water distributed by inhabitant. Then sustainability rankings at the municipality level were defined considering these factors. Finally, it was possible to conclude that tourism activity, income level, and young age population have a significant negative effect on sustainable water use, and municipal revenue has a positive effect. Irrigated farming shows a non-significant negative effect on sustainable water use. Population density, elderly population and education level did not show the expected effects on sustainable water use.
- Integration of fire risk in a sustainable forest management modelPublication . Costa Freitas, Maria de Belem; Xavier, Antonio; Fragoso, RuiIn Mediterranean areas, forest fires are a considerable risk most years. The seasonality of the climate with a dry summer, high temperatures and low rainfall (which implies increased flammability of materials) is one of the main factors in the ignition and progression of fires. This factor conjugated with more favourable biophysical conditions (e.g., high slopes, aspect) leads to easy propagation and the increasingly destructive power of such phenomena. To prevent and reduce the consequences of forest fires, it is necessary to simulate and forecast the territory use and management, not only focused on forest areas, but also on all land uses and agricultural activities that may coexist there, considering the probability of fire occurrence. The objective of this paper is to present a methodological approach to address the integration of fire risk in integrated Mediterranean forest management models. The methodological approach considers simultaneously the climatic conditions through different times of the year (more or less favourable to forest fire damage) and structural conditions addressed to land uses, aspect, slope, roads and demographic density. The methodological approach was implemented in a management area located in the Algarve, in southern Portugal. The results for the Algarve region showed that the proposed approach is very useful for managers, since it allowed the calculation of fire susceptibility, vulnerability and fire damage, according to several climatic scenarios. It also allowed the incorporation of different paths regarding different fire risk conditions and the minimization of risk due to fire damage through different management responses.