Análise de tendências e seus pontos de mudança na precipitação do estado do Rio Grande do Norte
Over the past few years, increasingly stronger evidence of possible climate change has surfaced, and its present and future effects in climate dynamics have been a constant object of study. It is predicted that these changes will have a considerable impact in water resources engineering, especial...
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Formato: | Dissertação |
Idioma: | pt_BR |
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Brasil
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Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/27786 |
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Resumo: | Over the past few years, increasingly stronger evidence of possible climate change has surfaced,
and its present and future effects in climate dynamics have been a constant object of study. It is
predicted that these changes will have a considerable impact in water resources engineering,
especially regarding the distribution, frequency and intensity of rainfall events. This research,
by consequence, aimed to investigate the existence of trends and change points in time series
data ranging from 1963 to 2010, from 48 rain gauges in the Brazilian state of Rio Grande do
Norte – which is located, in its majority, in an area of semiarid climate that often goes through
severe droughts. Thirteen indexes related to total and extreme values of precipitation were
calculated for each time series, and three different methods to detect these changes have been
chosen: the Mann-Kendall test for trend detection (with a pre-whitening approach for
autocorrelated time series), the Theil-Sen method for slope estimation and the Pettitt test for
change-point detection. Results show that, even though the changes in annual total precipitation
were not significant in their majority, various trends were identified for other indexes: drought
periods have become longer, precipitation events seemed to occur in fewer days and, mainly in
the eastern portion of the state, indexes associated with the frequency and intensity of extreme
events presented positive trends in several stations. Furthermore, when analyzed in a seasonal
scale, total precipitation seemed to decrease in numerous rain gauges over the years, both in
rainy and dry seasons. The Pettitt test attested that most of the detected change points
represented a positive variation, mostly for extreme event indexes and for the duration of
drought periods, and mostly occurred between the years of 1990 and 1995. Even though some
of the observed changes in this study can be partially explained by natural climatic phenomena
that occur periodically within the region, their persistence and significance might represent
important challenges for water resource management and risk prevention in the state of Rio
Grande do Norte. |
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