Análise temporal da fragilidade ambiental na bacia hidrográfica do rio Sorocabuçu, Ibiúna, SP
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2020-02-04
Autores
Costa, Hetiany Ferreira da
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Universidade Estadual Paulista (Unesp)
Resumo
O mapeamento da fragilidade ambiental é de extrema importância uma vez que integram variáveis naturais e antrópicas a fim de evidenciar as adequações no uso da terra, além de servirem como subsídio para o planejamento e gestão ambiental de paisagens no geral. Outro produto usado para auxiliar em tomadas de decisões é a simulação de cenários futuros do uso do solo e cobertura vegetal, onde conhecer uma possibilidade de cenário futuro auxilia no planejamento de caminhos para atingir ou distanciar desse cenário final. Assim, o objetivo desse estudo é elaborar e comparar o uso do solo e cobertura vegetal e a Fragilidade Ambiental entre 2010 e 2019, e desenvolver modelo baseado na Cadeia de Markov cenários futuros para a área. O estudo foi desenvolvido na Bacia Hidrográfica do Rio Sorocabuçu, situado em Ibiúna, São Paulo. A área está inserida no bioma Mata Atlântica, apresentando grande importância ambiental por estar inserida na Área de Preservação Ambiental de Itupararanga. A metodologia foi iniciada pela construção da base cartográfica de apoio, divisão das sub-bacias e no mapeamento de uso do solo e cobertura vegetal para 2010 (a partir de ortoimagens do sensor Vexcel Ultracam) e posterior retificação para 2019, utilizado para extrair os fragmentos florestais e gerar a fragilidade emergente baseada no grau de modificação que as diferentes classe de uso do solo e cobertura vegetal possui. Também foi gerada a declividade e extraído a pedologia da área a partir do mapeamento feito para o Estado de São Paulo. A declividade, pedologia e os fragmentos florestais foram utilizadas para gerar a Fragilidade Potencial. A Fragilidade Ambiental foi gerada a partir dos produtos obtidos na Fragilidade Potencial e Emergente. A partir do software TerrSet 18.10, pelo módulo Markov e CA_Markov, foi realizada a simulação de estado futuro do uso do solo e cobertura vegetal com posterior geração da Fragilidade Ambiental para 2028. A área de estudo apresenta, em sua maioria, Fragilidade Potencial muito baixa tanto para 2010 quanto para 2019 (49,59% e 49,86%, respectivamente) e o menor representativo é para alto grau de Fragilidade Potencial (0,71% e 0,77%). A Fragilidade Emergente é representada pelo muito baixo grau de modificação (54,22% e 53,09%), classe representada pelas matas e corpos d’água, e a menor representação é a média Fragilidade Emergente (2,13% e 2,45%). A Fragilidade Ambiental se concentra entre os graus muito baixo e baixo, somando aproximadamente 92% em ambas as datas, e não apresenta o alto e muito alto grau de fragilidade ambiental. Através da matriz de probabilidade de transição entre 2019 e 2028, obteve-se que a classe campo possui a maior probabilidade de mudança. As classes de campo e reflorestamento são as que apresentam maior probabilidade de substituírem as áreas ocupadas por vegetação. Foi possível verificar, também, que a diminuição de 1,7 km² da matas e o aumento das Áreas Urbanizadas. Quanto ao cenário da Fragilidade Ambiental em 2028, houve o aumento de aproximadamente 2 km² para o médio grau, além do aparecimento do alto grau de Fragilidade Ambiental. A muito baixa/baixa fragilidade da área se deu pela presença de solo de baixa fragilidade, declividade em sua extrema maioria de média fragilidade e grande presença de remanescente florestal. A proposta do cenário futuro indicou o aumento das áreas antrópicas e consequente diminuição das áreas com cobertura vegetal, bem como o aumento da fragmentação florestal.
The mapping of environmental fragility is extremely important as it integrates natural and anthropogenic variables in order to highlight land use adequacy, as well as serving as a subsidy for the planning and environmental management of landscapes in general.Another product used to assist in decision-making is the simulations of possible future scenarios of land and use occupation, where knowing a possibility of this helps in planning the paths to reach or distance from this final scenario. Therefore, the aim of this reaserch was to elaborate and compare the land use and occupation and environmental fragility between 2010 – 2019 and to develop a model based on Markov Chain to simulate future scenarios. The reaserch was develop in Sorocabuçu River Watershed, located in Ibiúna, São Paulo. Inserted in the Atlantic Forest biome and mainly in the Itupararanga Environmental Preservation Area, the watershed presents great environmental relevance. The methodology applied was initiated by the construction of the cartography base support, division of subwatershed and in the mapping of land use and occupation for (from orthoimaging of the Vexcel Ultracam sensor) and subsequent rectification to 2019, used to extract the forest fragments and generate the emerging fragility based on the degree of modification that different class of use and occupation has. Also, was the slope was generated and the pedology of the area was extracted from mapping carried out for the State of São Paulo. The slope, pedology and forest fragmentes were used to generate potencial fragility. The environmental fragility was generated from the products obtained in potencial and emergent fragility. From the TerrSet 18.10 software, from “Markov” and “CA_Markov” modules it was carried out the simulation of future scenario of the land use and occupation and environmental fragility. Most of the study area has very low potential fragility both for 2010 and 2019 (49,59% and 49,86%, respectively) and the lowest representative is for a high degree of potential fragility (0,71% and 0,77%). Emergent fragility is also more represented by the very low degree of change for 2010 and 2019 (54,22% and 53,09%), a class represented by the forests, and the lowest representation is the average emergent fragility (2,13% and 2,45%). Environmental fragility is concentrated between very low and low extent, accounting for approximately 92% in 2010 and 2019, and no presents high and very high degree of environmental fragility. Through the transition probability matrix between 2019 and 2028, it was obtained that the field class has the highest probability of change. Field and reforestation classes are those most likely to replace areas occupied by vegetation. It was also possible to verify that the decrease of 1.7 km² of forests and the increase of urbanized areas. Regarding the scenario of Environmental Fragility in 2028, there was an increase of approximately 2 km² for the medium degree, in addition to the appearance of the high degree of Environmental Fragility. The very low/low fragility of the area was due to the presence of soil of low fragility, slope in its extreme majority of medium fragility and great presence of remnant forest. The proposal of the future scenario indicated the increase of anthropic areas and consequent decrease of areas with vegetation cover, as well as the increase of forest fragmentation.
The mapping of environmental fragility is extremely important as it integrates natural and anthropogenic variables in order to highlight land use adequacy, as well as serving as a subsidy for the planning and environmental management of landscapes in general.Another product used to assist in decision-making is the simulations of possible future scenarios of land and use occupation, where knowing a possibility of this helps in planning the paths to reach or distance from this final scenario. Therefore, the aim of this reaserch was to elaborate and compare the land use and occupation and environmental fragility between 2010 – 2019 and to develop a model based on Markov Chain to simulate future scenarios. The reaserch was develop in Sorocabuçu River Watershed, located in Ibiúna, São Paulo. Inserted in the Atlantic Forest biome and mainly in the Itupararanga Environmental Preservation Area, the watershed presents great environmental relevance. The methodology applied was initiated by the construction of the cartography base support, division of subwatershed and in the mapping of land use and occupation for (from orthoimaging of the Vexcel Ultracam sensor) and subsequent rectification to 2019, used to extract the forest fragments and generate the emerging fragility based on the degree of modification that different class of use and occupation has. Also, was the slope was generated and the pedology of the area was extracted from mapping carried out for the State of São Paulo. The slope, pedology and forest fragmentes were used to generate potencial fragility. The environmental fragility was generated from the products obtained in potencial and emergent fragility. From the TerrSet 18.10 software, from “Markov” and “CA_Markov” modules it was carried out the simulation of future scenario of the land use and occupation and environmental fragility. Most of the study area has very low potential fragility both for 2010 and 2019 (49,59% and 49,86%, respectively) and the lowest representative is for a high degree of potential fragility (0,71% and 0,77%). Emergent fragility is also more represented by the very low degree of change for 2010 and 2019 (54,22% and 53,09%), a class represented by the forests, and the lowest representation is the average emergent fragility (2,13% and 2,45%). Environmental fragility is concentrated between very low and low extent, accounting for approximately 92% in 2010 and 2019, and no presents high and very high degree of environmental fragility. Through the transition probability matrix between 2019 and 2028, it was obtained that the field class has the highest probability of change. Field and reforestation classes are those most likely to replace areas occupied by vegetation. It was also possible to verify that the decrease of 1.7 km² of forests and the increase of urbanized areas. Regarding the scenario of Environmental Fragility in 2028, there was an increase of approximately 2 km² for the medium degree, in addition to the appearance of the high degree of Environmental Fragility. The very low/low fragility of the area was due to the presence of soil of low fragility, slope in its extreme majority of medium fragility and great presence of remnant forest. The proposal of the future scenario indicated the increase of anthropic areas and consequent decrease of areas with vegetation cover, as well as the increase of forest fragmentation.
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Palavras-chave
Fragilidade Ambiental, Cadeias de Markov, Geoprocessamento, Environmental Fragility, Markov Chain, Geoprocessing