Abstract
Climate changes have been observed all over the world and are pointed out as responsible to impact the natural resources, especially the amount and the quality of the water in a hydrographic basin. Thus, the present research aimed to analyze the variability and trends of air temperature and rainfall data in the Hydrographic Basin of the Ribeirão do Lobo, São Paulo state, Brazil. The weather data from 1988 to 2017 were collected in the Center of Water Resources and Environment Studies of the University of São Paulo (CRHEA), and in five rainfall stations of the National Water Agency of Brazil (ANA) spread all over the basin. To identify climate changes were applied the simple regression, the run test, the Mann-Kendall and modified Mann-Kendall tests. The results showed significant positive trends in air temperature, especially in the annual period and during the third quarter with rising up to 0.068 °C year-1. Significant increases were verified to minimum, maximum and mean air temperature, which suggests possible climate changes during the period in the analysis. To the rainfall data, periods with positive and negative trends were found, although, most of the time the trends were non-significant. However, a significant negative trend of the rainfall was observed in Ribeirão do Feijão station with a reduction of -10.03 mm year-1. Variabilidade e tendência da temperatura do ar e precipitação na Bacia Hidrográfica do Ribeirão do Lobo, Brasil R E S U M OAs mudanças climáticas têm sido observadas em todo o mundo e são apontadas como responsáveis por impactar os recursos naturais, especialmente a quantidade e a qualidade da água em uma bacia hidrográfica. Assim, o presente trabalho teve como objetivo analisar a variabilidade e as tendências da temperatura do ar e da chuva na Bacia Hidrográfica do Ribeirão do Lobo, Estado de São Paulo, Brasil. Os dados meteorológicos de 1988 a 2017 foram coletados no Centro de Recursos Hídricos e Estudos Ambientais da Universidade de São Paulo (CRHEA), e em cinco estações pluviométricas da Agência Nacional de Águas do Brasil (ANA) distribuídas por toda a bacia. Para identificar as mudanças climáticas, foram aplicados os testes de regressão simples, teste de run, Mann-Kendall e Mann-Kendall modificado. Os resultados mostraram tendências positivas significativas na temperatura do ar, especialmente no período anual e durante o terceiro trimestre, com aumento de até 0,068 °C por ano. Aumentos significativos foram verificados para temperatura mínima, máxima e média do ar, o que sugere possíveis mudanças climáticas no período analisado. Para os dados de chuva, foram encontrados períodos com tendências positivas e negativas, contudo, na maioria das vezes, as tendências não foram significativas. No entanto, uma tendência negativa significativa da precipitação foi observada na estação de Ribeirão do Feijão com redução de -10,03 mm ao ano.Palavras-chave: mudanças climáticas, regressão simples, Mann-Kendall, tendência.
Highlights
Climate changes are defined as modification over the climate conditions through 30 years and, can be represented by air temperature rises, changes in rainfall patterns and by the increase of the frequency and intensity of extreme meteorological events
Annual data variability Analyzing the air temperature data from the CRHEA climatological station for the whole period, it was verified that the average minimum air temperature (Tmin) was of 14.0 °C, which presented a minimum value of 12.0 °C and maximum of 16.5 °C observed in 1999 and 2015, respectively
Fante and Sant’Anna Neto (2017) analyzing changes in the air temperature patterns into the São Paulo state, found that raises in the minimum air temperature was more prominent compared with maximum air temperature
Summary
Climate changes are defined as modification over the climate conditions through 30 years and, can be represented by air temperature rises, changes in rainfall patterns and by the increase of the frequency and intensity of extreme meteorological events. According to the International Panel of Climate Change (IPCC, 2013), these modifications are considered as non-natural, are associated with the global warming, that can be the result of the human activities, which emit greenhouse gases, as carbon dioxide and methane into the atmosphere. Climate changes can be resulted by natural causes and, other human activities, for example, changes in land use. The impact of the climate changes over natural resources are diverse and, promote drawbacks in the agriculture (Verhage et al, 2017) human health and food security (Myers et al, 2017) and, at the economic and social development of a region. The evaluation of these impacts must encompass different areas (agriculture, hydric resources, infrastructure and, industrial production) and spatial scale (local, regional and global) (Huber et al, 2014)
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