Stationarity in Annual Daily Maximum Streamflow Series in the Hydrographic Basin of the Upper Juruá River, Western Amazon

Abstract

The objective of this study was to investigate the hypothesis of stationary behavior in the streamflow regime of the upper Juruá river. For this purpose, annual maximum daily flow data recorded at stations located in Cruzeiro do Sul and Marechal Thaumaturgo, AC, Brazil, were analyzed using Mann-Kendall, Pettitt, and Spearman's Rho tests. The results show sufficient evidence to conclude that in Cruzeiro do Sul flow rates have an ascending temporal behavior, while in Marechal Thaumaturgo it is descending. However, this tendency is not significant (p<0.05), allowing to conclude in favor of the hypothesis of stationarity in the streamflow series of the referred basin. Thus, one of the physical implications associated to the results obtained may be the conclusion that the streamflow regime in the Upper Juruá basin has not changed significantly over time. Key words: stationarity, annual maximum daily flow, Upper Juruá basin. R E S U M O O presente estudo tem o objetivo de investigar a hipótese de comportamento estacionário no regime de vazões do alto rio Juruá. Para tal, foram utilizadas as séries temporais de vazões diárias máximas anuais, gravados nas estações localizadas em Cruzeiro do Sul e Marechal Thaumaturgo, as quais foram analisadas por meio do teste de Mann-Kendall, de Pettitt e do Spearman Rho teste. Os resultados demonstram evidências suficientes para concluir que, em Cruzeiro do Sul, as vazões apresentam comportamento temporal ascendente, enquanto em Marechal Thaumaturgo descendente. Entretanto, tal inclinação não é significativa (p<0,05), permitindo concluir em favor da hipótese de estacionariedade nas séries de vazões da referida bacia hidrográfica. Assim, uma das implicações físicas associadas aos resultados obtidos pode ser a conclusão de que o regime de vazões na bacia do Alto Juruá não sofreu alterações significativas ao longo do tempo. Palavras-chave: estacionariedade, vazões máximas, Bacia do Alto Juruá.

Distribuição espaço-temporal das anomalias de precipitação pluviométrica no Acre

“…Conversely, both weather stations have a dry season from June to August, with an average rainfall variation of 52.83 mm to 88.33 mm. The results are in line with what is reported by Moreira et al (2019), where it is highlighted that the region is divided into two rainfall periods, one drier and one notably rainy, with an average annual precipitation of around 2,000 mm but with high rainfall variation.…”

Probability of rainfall for the city of Cruzeiro do Sul, Acre, Brazil

“…It is noteworthy, nevertheless, that both the scientific community and other organizations are already reaching the consensus that the impacts of climate change (on a global and/or regional scale) are already influential on the Amazon. As a result, the rainfall regime in the region under study may change its patterns and, consequently, the estimated values, since hydrological processes, especially rainfall regime, are quite sensitive to climate change (Moreira et al, 2019;Marengo and Souza Júnior, 2018).…”

“…In this work, the total monthly and annual rainfall data was used, computed for the city of Cruzeiro do Sul, during the period from 1970 to 2019, recorded at the meteorological station 82704 (7º38' S; 72º40' W, in datum WGS84), operated by the National Institute of Meteorology (INMET) (Souza et al, 2011;Moreira et al, 2019) (Figure 1). There are occasional failures in the records in the years 1991 and 1992, corresponding to 4% of the records, whose monthly values were filled out using the regional weighting method (Oliveira et al, 2010).…”

“…In addition, the realization of this work is justified, since the estimated values of rainfall precipitation can be influenced over time, due to several factors, among them, the climatic changes credited to anthropic actions, as well as those related to the natural climate variability that, collectively or in isolation, have an effect on the hydrological processes operating in the region (Moreira et al, 2019;Marengo and Souza Júnior, 2018).…”

Modelagem de vazões máximas e mínimas com base em aprendizado de máquina

“…O teste de MK apresenta como limitação a necessidade de dados independentes e aleatórios, a qual foi superada pela modificação feita por Hamed e Rao (1998) no cálculo da variância dos dados. Quanto ao teste SP, ele é equivalente ao teste de Mann-Kendall, de fácil implementação e é comumente utilizado com o teste de MK para fins de comparação ou análise complementar da tendência (ASHRAF et al, 2021;MOREIRA et al, 2019;SÖNMEZ;KALE, 2020). A inclinação de TSS, contudo, não apresenta nenhuma suposição, sendo aplicada em conjunto com os demais testes para identificar a magnitude da tendência (MOHAMMED et al, 2022;NOURANI;DANANDEH MEHR;AZAD, 2018).…”