Diagnóstico da variabilidade espacial e temporal da pluviometria e caracterização das secas na região Alto Rio Paraná: 1990 a 2020
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2022-02-18
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Universidade Estadual Paulista (Unesp)
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A carência de dados hidrológicos e o cenário de escassez hídrica fazem necessário um novo horizonte de planejamento das águas que depende da investigação das variáveis hidrológicas. Técnicas de regionalização que permitem a transferência de informações entre áreas homogêneas e o uso de métodos geoespaciais tornam possível o monitoramento contínuo e preventivo das chuvas em macroescala. Devido à crítica situação de escassez hídrica situada sobre a Região Hidrográfica do Rio Paraná e sua relevância nacional, o estudo teve como objetivo geral avaliar a variabilidade espaço-temporal das chuvas na região do alto curso do rio Paraná (Alto Rio Paraná) e a possível influência do El Niño – Oscilação Sul (ENOS) nas chuvas anuais durante o período de 1990 a 2020. A área de estudo compreende 14 unidades hídricas de planejamento das águas, distribuídas nos estados de Goiás, Mato Grosso do Sul, Minas Gerais e São Paulo. Os dados de precipitação foram obtidos junto ao banco de dados da Rede Hidrometeorológica Nacional. A priori foi analisada a disponibilidade temporal e espacial dos dados e proposta uma classificação para a densidade da rede observacional da área de estudo, além da identificação de áreas homogêneas de chuva para subsidiar a análise de consistência de dados. A determinação de regiões pluviométricas foi avaliada com base no Teste de Homogeneidade do Método dos Momentos-L. Posteriormente, efetuou-se o mapeamento da chuva, a partir das séries anuais de 408 estações, e o cálculo do Índice de Porcentagem Normal (IPN) para identificação e classificação da severidade das secas na região, realizando-se a interpolação dos dados por krigagem ordinária. Todos os mapas para os anos de 1990 a 2020 apresentaram dependência espacial moderada a alta, conforme seus ajustes semivariográficos, possibilitando a análise da influência do ENOS nas chuvas anuais, bem como a obtenção das médias decenais e normais para as regiões homogêneas e unidades hídricas. Os períodos e áreas secas e chuvosas foram avaliadas, não encontrando influência direta do ENOS, com base no Índice Oceânico Niño. Por fim, foram discutidos os impactos da escassez pluviométrica na região Alto Rio Paraná e efetuada a classificação das unidades quanto à vulnerabilidade da rede observacional e dos setores usuários. As análises possibilitaram identificar as unidades de Mato Grosso do Sul e São Paulo como maiores contribuintes nas secas identificadas na região Alto Rio Paraná, além de 2010 como decênio mais seco do período analisado, com maior contribuição do período de 2019/2020, onde as secas atingiram mais de 60% da área por dois anos consecutivos, evento nunca identificado nas últimas 3 décadas. As curvas do IPN respectivas à seca e umidade inicial permitiram verificar anos de crise hídrica e alta umidade quando seus percentuais atingiram 50% da região analisada. A metodologia para manipulação dos dados oficiais apresenta grande versatilidade permitindo seu uso em qualquer bacia hidrográfica. As classificações propostas para as unidades de gestão indicaram que a capacidade de gestão das águas na região deve ser aprimorada sob diferentes respectivas, tendo em vista a persistência no cenário de secas e a insuficiência da rede observacional.
The lack of hydrological data and the scenario of water scarcity make a new horizon of water planning necessary, which depends on the investigation of hydrological variables. Regionalization techniques that allow the transfer of information between homogeneous areas and the use of geospatial methods make possible the continuous and preventive monitoring of rainfall on a macroscale. Due to the critical situation of water scarcity located over the Paraná River Hydrographic Region and its national relevance, the study aimed to evaluate the spatio-temporal variability of rainfall in the upper course of the Paraná River (Upper Paraná River) and the possible influence of El Niño – Southern Oscillation (ENSO) on annual rainfall during the period from 1990 to 2020. The study area comprises 14 water planning units, distributed in the states of Goiás, Mato Grosso do Sul, Minas Gerais and São Paulo. Precipitation data were obtained from the database of the National Hydrometeorological Network. First, the temporal and spatial availability of the data was analyzed and a classification for the density of the observational network in the study area was proposed, in addition to the identification of homogeneous areas of rainfall to support the analysis of data consistency. The determination of the rainfall regions was evaluated based on the Homogeneity Test of the L-Moments Method. Subsequently, the rainfall mapping was carried out, based on the annual series of 408 stations, and the calculation of the Normal Percentage Index (IPN) to identify and classify the severity of droughts in the region, performing data interpolation by ordinary kriging. All maps for the years 1990 to 2020 showed moderate to high spatial dependence, according to their semivariographic adjustments, allowing the analysis of the influence of ENSO on annual rainfall, as well as obtaining decennial and normal averages for homogeneous regions and water units. The dry and rainy periods and areas were evaluated, finding no direct influence of ENSO, based on the Oceanic Niño Index. Finally, the impacts of rainfall scarcity in the Alto Rio Paraná region were discussed and the units were classified according to the vulnerability of the observational network and user sectors. The analyzes made it possible to identify the units of Mato Grosso do Sul and São Paulo as the largest contributors to the droughts identified in the Alto Rio Paraná region, in addition to 2010 as the driest decade of the analyzed period, with the greatest contribution from the period 2019/2020, where droughts reached more than 60% of the area for two consecutive years, an event never identified in the last 3 decades. The IPN curves related to drought and initial humidity allowed us to verify years of water crisis and high humidity when their percentages reached 50% of the analyzed region. The methodology for handling official data is highly versatile, allowing its use in any watershed. The classifications proposed for the management units indicated that the water management capacity in the region must be improved under different respective ones, in view of the persistence in the scenario of droughts and the insufficiency of the observational network.
The lack of hydrological data and the scenario of water scarcity make a new horizon of water planning necessary, which depends on the investigation of hydrological variables. Regionalization techniques that allow the transfer of information between homogeneous areas and the use of geospatial methods make possible the continuous and preventive monitoring of rainfall on a macroscale. Due to the critical situation of water scarcity located over the Paraná River Hydrographic Region and its national relevance, the study aimed to evaluate the spatio-temporal variability of rainfall in the upper course of the Paraná River (Upper Paraná River) and the possible influence of El Niño – Southern Oscillation (ENSO) on annual rainfall during the period from 1990 to 2020. The study area comprises 14 water planning units, distributed in the states of Goiás, Mato Grosso do Sul, Minas Gerais and São Paulo. Precipitation data were obtained from the database of the National Hydrometeorological Network. First, the temporal and spatial availability of the data was analyzed and a classification for the density of the observational network in the study area was proposed, in addition to the identification of homogeneous areas of rainfall to support the analysis of data consistency. The determination of the rainfall regions was evaluated based on the Homogeneity Test of the L-Moments Method. Subsequently, the rainfall mapping was carried out, based on the annual series of 408 stations, and the calculation of the Normal Percentage Index (IPN) to identify and classify the severity of droughts in the region, performing data interpolation by ordinary kriging. All maps for the years 1990 to 2020 showed moderate to high spatial dependence, according to their semivariographic adjustments, allowing the analysis of the influence of ENSO on annual rainfall, as well as obtaining decennial and normal averages for homogeneous regions and water units. The dry and rainy periods and areas were evaluated, finding no direct influence of ENSO, based on the Oceanic Niño Index. Finally, the impacts of rainfall scarcity in the Alto Rio Paraná region were discussed and the units were classified according to the vulnerability of the observational network and user sectors. The analyzes made it possible to identify the units of Mato Grosso do Sul and São Paulo as the largest contributors to the droughts identified in the Alto Rio Paraná region, in addition to 2010 as the driest decade of the analyzed period, with the greatest contribution from the period 2019/2020, where droughts reached more than 60% of the area for two consecutive years, an event never identified in the last 3 decades. The IPN curves related to drought and initial humidity allowed us to verify years of water crisis and high humidity when their percentages reached 50% of the analyzed region. The methodology for handling official data is highly versatile, allowing its use in any watershed. The classifications proposed for the management units indicated that the water management capacity in the region must be improved under different respective ones, in view of the persistence in the scenario of droughts and the insufficiency of the observational network.
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Palavras-chave
MML, Região Homogênea, IPN, Krigagem, Seca, Homogeneous region, NPI, Kriging, Dry