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- Automatic detection of vegetation cover changes in urban-rural interface areasPublication . Barbosa, Bruno; Rocha, Jorge; Costa, Hugo; Caetano, MárioThe present work started from the need to streamline the process of monitoring changes in vegetation in the in urban-rural interface fuel management bands, defined by Portuguese legislation as areas where the existing biomass must be totally or partially removed. The model developed uses a time series of Sentinel 2 satellite images to search for changes in the vegetation cover in a 100 m buffer around built-up areas. The use of satellite data allows analysing large areas and speeds up the task of identifying the places where fuel management took place and the places where there is a need to carry out such management. The objective of the proposed method is to give a script in Python language that can verify the cleanliness of vegetation in the fuel management ranges through multi-temporal analysis of satellite images. • The paper presents a step-by-step procedure for a Sentinel 2 time series vegetation index analysis. • Automated routine to detection of spatiotemporal vegetation changes based on statistical parameters. • Used Python language to do geoprocessing analysis.
- Detecção Automática de Alterações de Coberto Vegetal em Áreas de Interface Urbano-RuralPublication . Barbosa, Bruno; Costa, Hugo; Rocha, Jorge; Caetano, MárioPara fazer face aos incêndios florestais o SDFCI estabelece faixas de gestão de combustíveis como forma de auxiliar o combate e mitigação deste problema. O objetivo do trabalho foi elaborar um modelo capaz de identificar a remoção da vegetação nestas faixas através da análise do NDVI em séries temporais de imagens Sentinel 2. O modelo busca diferenças estatisticamente significantes, através do Welch t-test, nas informações contidas nas imagens. O modelo foi aplicado no concelho de Figueiró dos Vinhos e os resultados mostraram-se promissores na identificação de áreas onde não foi feita a gestão, ou seja, áreas de infração a legislação.
- Uncovering vegetation changes in the urban–rural interface through semi-automatic methodsPublication . Barbosa, Bruno; Rocha, Jorge; Costa, Hugo; Caetano, MárioForest fires are considered by Portuguese civil protection as one of the most serious natural disasters due to their frequency and extent. To address the problem, the Fire Forest Defense System establishes the implementation of fuel management bands to aid firefighting. The aim of this study was to develop a model capable of identifying vegetation removal in the urban–rural interface defined by law for fuel management actions. The model uses normalised difference vegetation index (NDVI) of Sentinel-2 images time series and is based on the Welch t-test to find statistically significant differences between (i) the value of the NDVI in the pixel; (ii) the mean of the NDVI in the pixels of the same land cover type in a radius of 500 m; and (iii) their difference. The model identifies a change when the t-test points for a significant difference of the NDVI value in the ‘pixel’ as comparted to the ‘difference’ but not the ‘mean’. We use a moving window limited to 60 days before and after the analysed date to reduce the phenological variations of vegetation. The model was applied in five municipalities of Portugal and the results are promising to identify the places where the management of fuel bands was not carried out. This indicates which model could be used to assist in the verification of the annual management of the fuel bands defined in the law.
- Mapping the wildland-urban interface at municipal level for wildfire exposure analysis in mainland PortugalPublication . Barbosa, Bruno; Oliveira, Sandra; Caetano, Mário; Rocha, JorgeThe Wildland-Urban Interface (WUI), where vegetation and built-up structures intermingle, encompasses a variety of territorial elements that interact spatially, being variable both in space and time. Mapping the WUI at finer scales is paramount to assess wildfire exposure and define tailored mitigation strategies. Our aim was to develop a semi-automated method to map the WUI at municipal level, leveraging recent advances in data and technology. We tested the procedure in four municipalities of mainland Portugal with different fire history, biophysical conditions, and sociodemographic contexts. We considered WUI as either intermix or interface. Our approach integrates both building location data and high-resolution vegetation maps, to calculate the density of buildings and forest cover proportion within different circular moving window sizes. Within each radius, we evaluated the total area and spatial distribution of the WUI types, as well as the number of buildings within WUI and within the fire perimeters recorded between the years 2000 and 2022 and analysed the differences between municipalities. We then compared the mapped WUI with previous WUI mappings for mainland Portugal, to identify common spots and potential spatial divergences. We found that the area mapped as WUI within all four municipalities ranged from about 400 km2 to 1135 km2 depending on the radius size. A distinct distribution for each type of WUI was observed as the radius size increased: the intermix WUI showed a tendency to increase, and the interface WUI increased only between the radius of 100 and 200 m, decreasing gradually in subsequent radii. Between 39.4% and 45.5% of the nearly 200,000 buildings in the study areas were within WUI, depending on radius size and a total of 5436 buildings were within the historic fire perimeter. Although the comparison with other maps showed fair agreement, due to differences in data and methodology, common areas mapped as WUI were found, which suggests that these areas should receive greater attention from decision-makers regarding fire management strategies, since their classification as WUI remains consistent across different methodologies.
- Detecção automática de alterações de coberto vegetal em áreas de interface urbano-ruralPublication . Barbosa, Bruno; Costa, Hugo; Rocha, Jorge; Caetano, MárioPara fazer face aos incêndios florestais o Sistema de Defesa da Floresta contra Incêndios estabelece faixas de gestão de combustíveis como forma de auxiliar o combate e mitigação deste problema. O objetivo do trabalho foi elaborar um modelo capaz de identificar o controlo da biomassa nestas faixas através da análise do NDVI em séries temporais de imagens Sentinel 2. O modelo busca diferenças estatisticamente significativas, através do Welch t-test, nas informações contidas nas imagens. O modelo foi aplicado no concelho de Figueiró dos Vinhos e os resultados mostraram-se promissores na identificação de áreas onde não foi feita a gestão, ou seja, áreas de infração à legislação.