Abstract
ABSTRACTThe high variability in the hydrological regime of the Eastern Hydrological Region (EHR) of Northeast Brazil often results in floods and droughts, leading to serious socio-economic issues. Therefore, this work aimed to investigate connections between spatiotemporal hydrological variability of the EHR and large-scale climate phenomena. Multivariate statistical techniques were applied to relate climate indices with hydrological variables within two representative river basins in the EHR. The results indicated a multi-annual relationship between the state of the sea surface temperature of the Atlantic and Pacific oceans and anomalous hydrological variability in the basins. In addition, the northern Tropical Atlantic conditions were shown to play an important role in modulating the long-term variability of the hydrological response of the basins, whilst only extreme ENSO anomalies seemed to affect the rainy season. This knowledge is an important step towards long-term prediction of hydrological conditions and contributes to the improvement of water resources planning and management in the EHR.
Highlights
Variability in climate conditions can lead to significant worldwide impacts on the hydrological regime, increasing the chances of extreme events such as floods or droughts (Labat 2010, Massei and Fournier 2012, Räsänen and Kummu 2013) causing damage to human activities and, economic losses
The first four modes of the rotated Principal component analysis (PCA) together explain 80.5% of the total variance of the MJJ precipitation, with 69.1% being explained by the three first modes (Table 1). which presented characteristics clearly connected to spatial distribution of the local climate
The temporal variability of the precipitation appears to be influenced by large-scale climate conditions, since the simultaneous Spearman correlation indicates that there are significant correlations between the modes of the rotated PCA and climate indices
Summary
Variability in climate conditions can lead to significant worldwide impacts on the hydrological regime, increasing the chances of extreme events such as floods or droughts (Labat 2010, Massei and Fournier 2012, Räsänen and Kummu 2013) causing damage to human activities and, economic losses. Efforts have been developed to identify the role of the large-scale atmospheric and oceanic circulations in the dynamics of hydrological variability in both the short and long term, as well as the relationship between hydrological anomalies and large-scale climate variability (Uvo 2003, Andreoli and Kayano 2005, Massei and Fournier 2012, Räsänen and Kummu 2013, Grimm and Saboia 2015, Tedeschi et al 2016, Berton et al 2017) The understanding of such relationship provides a major step towards predicting hydrological conditions weeks or months ahead. Total annual precipitation may vary from less than 600 mm in the semi-arid part of NEB to up to 1600 mm along the coastal zones (Rao et al 1993, Uvo et al 1998, Amorim et al 2014, Cunha et al 2015)
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