ResumoO Centro-Oeste brasileiro era extensivamente coberto por fitofisionomias de Savanas até o final da década de 1970, quando se iniciaram amplas transformações, devido à expansão da fronteira agrícola e modernização da agricultura, que promoveram desmatamento intensivo e rápido. A vegetação que resta hoje se encontra na forma de fragmentos, os quais podem sofrer vários efeitos que podem levar à diminuição ou desaparecimento de espécies. As mudanças ocorridas em uma paisagem podem ser estudadas pelos métodos da Ecologia da Paisagem, por meio da avaliação de índices ou métricas para caracterização quantitativa, permitindo também comparar paisagens, identificar diferenças e determinar relações entre os processos funcionais e os padrões dessas paisagens. O objetivo deste trabalho foi analisar a estrutura da paisagem na alta bacia do rio Araguaia, em cinco épocas (1977, 1989, 1997, 2002 e 2006) para avaliar o seu padrão de fragmentação ao longo do tempo após desmatamento intenso. Os resultados mostram que a metodologia utilizada foi satisfatória, a fragmentação revela notável taxa de conversão das fitofisionomias originais em favor de pastagem e agricultura e as métricas de área, área central, forma e isolamento, mostram que os fragmentos encontram-se sob forte ameaça em relação à sua integridade. Palavras-chave: Métricas da paisagem; Fragstats; fragmentação; integridade dos fragmentos. AbstractLandscape structure analysis of the upper Araguaia river basin in the brazilian savanna. The CentralWest region of Brazil was extensively covered by Savanna physiognomies at the end of 1970`s, when large transformations, due to expansion of agriculture frontier and agriculture modernization, promoted an intensive and fast deforestation. The vegetation that remains today is in the fragments form, which can suffer several effects that can lead to the decrease or disappearance of species. The changes that occurred in a landscape can be studied through the methods of Landscape Ecology, by evaluating the indices or metrics for quantitative characterization, allowing to compare landscapes, identify differences and determine relationships between the functional processes and the patterns of those landscapes. The objective of this paper was to analyze the structure of the landscape in the upper Araguaia river basin, in five years (1977, 1989, 1997, 2002 and 2006), to evaluate its pattern of fragmentation along the time, after the intensive deforestation. The results showed that the methodology used was satisfactory. The fragmentation revealed notable rate of conversion of the original physiognomies in pasture and agricultural lands and the metrics of the area, core area, shape and isolation of the natural classes showed that the fragments, in relation to its integrity, are under strong threat. Keywords: Landscape metrics; Fragstats; fragmentation; fragments integrity. INTRODUÇÃOO Centro-Oeste brasileiro se apresentava extensamente coberto por fitofisionomias de savanas até a década de 1970. Amplas transformações nas suas paisagen...

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The increasing figures of natural disasters and related human and material losses represent a major challenge to be faced by the Brazilian government, the scientific community and civil society all together. Landslides and floods resulting from climatic extremes have been associated not only to global climatic changes, but mostly due to the increase of population vulnerability and the lack of effective mitigation actions. Core governmental responses to mitigate such losses include the creation of operational centers for disaster monitoring and management -Cemaden (National Early Warning and Monitoring Centre of Natural Disasters) and CENAD (Centro Nacional de Gerenciamento de Riscos e Desastres). The establishment of these institutions associated with investments to map risky areas are key to implement landslides and floods monitoring systems. Despite significant investments, the implementation of such natural disaster monitoring systems depend much on cooperative actions among organizations and entities from different sectors of the society. The main objective of this work is to present the challenges and perspectives of innovative digital ecosystems designed to effectively monitor, warn and respond to natural disasters related to landslides and floods in Brazil. The several methodologies adopted make use of technical, scientific and empirical knowledge to establish a rain gauge network of 1400 automatic pluviometers and 1100 semiautomatic pluviometers, distributed in more than 800 municipalities defined as priority ones by the Brazilian National Plan of Risk Management and Response to Natural Disasters. Pilot projects of landslides monitoring systems are also included in the methodology in key municipalities where the number of human losses has been significant in recent disasters. In order to develop such challenging methodologies, Cemaden has worked together with the Center for Information Technology Renato Archer (CTI), CENAD, a number of research institutions, the private sector, local and regional governments and non-governmental organizations as well as the civil society. The combination of different types of knowledge, technological approaches and levels of interaction to population under risk of such a variety of organizations shall configure a collective intelligence able to improve the efficiency and confidence of early warnings of landslides and floods, as well as to promote further commitment of local governments and communities to respond to warnings. Categories and Subject Descriptors H.3.4 [Information storage and retrieval]:Systems and software -current awareness systems (selective dissemination of information--SDI), information networks, performance evaluation (efficiency and effectiveness), question-answering (fact retrieval), user profiles and alerts systems.

Abstract. On 15 February 2022, the city of Petrópolis in the highlands of the state of Rio de Janeiro, Brazil, received an unusually high volume of rain within 3 h (258 mm), generated by a strongly invigorated mesoscale convective system. It resulted in flash floods and subsequent landslides that caused the deadliest landslide disaster recorded in Petrópolis, with 231 fatalities. In this paper, we analyzed the root causes and the key triggering factors of this landslide disaster by assessing the spatial relationship of landslide occurrence with various environmental factors. Rainfall data were retrieved from 1977 to 2022 (a combination of ground weather stations and the Climate Hazards Group InfraRed Precipitation – CHIRPS). Remotely sensed data were used to map the landslide scars, soil moisture, terrain attributes, line-of-sight displacement (land surface deformation), and urban sprawling (1985–2020). The results showed that the average monthly rainfall for February 2022 was 200 mm, the heaviest recorded in Petrópolis since 1932. Heavy rainfall was also recorded mostly in regions where the landslide occurred, according to analyses of the rainfall spatial distribution. As for terrain, 23 % of slopes between 45–60∘ had landslide occurrences and east-facing slopes appeared to be the most conducive for landslides as they recorded landslide occurrences of about 9 % to 11 %. Regarding the soil moisture, higher variability was found in the lower altitude (842 m) where the residential area is concentrated. Based on our land deformation assessment, the area is geologically stable, and the landslide occurred only in the thin layer at the surface. Out of the 1700 buildings found in the region of interest, 1021 are on the slope between 20 to 45∘ and about 60 houses were directly affected by the landslides. As such, we conclude that the heavy rainfall was not the only cause responsible for the catastrophic event of 15 February 2022; a combination of unplanned urban growth on slopes between 45–60∘, removal of vegetation, and the absence of inspection were also expressive driving forces of this disaster.