Streamflow variability of the Neuquén river on the phases of its annual cycle and it relationship with climate indices

• Main Authors: Ricetti, Lorenzo, Hurtado, Santiago I., Agosta Scarel, Eduardo, Cesanelli, Andrés
• Format: Article in Journal/Newspaper
• Language: Spanish
• Published: Centro Argentino de Meteorólogos 2024
• Subjects: Northern Patagonia; El Niño Southern Oscillation; Southern Annular Mode; Indian Ocean Dipole; Atlantic Ocean; Patagonia norte; El niño oscilación del Sur; modo anular del sur; dipolo del Océano Índico; Océano Índico; North Atlantic
• Online Access: https://revistas.unlp.edu.ar/meteorologica/article/view/16712

The Neuquén river has great relevance for the northern Patagonian region. For this reason, this work aims to study it streamflow variability based on observational data in the context of hydrological emergency in the basin. Firstly, a study of daily streamflow infilling methods was performed, from which the multiple linear regression stood out as the most appropriate for the basin. Then, the phases of the annual cycle were determined with an objective methodology. The methodology was able to determine the beginning and ending dates in each of the three identified phases, in concordance with the river’s pluvio-nival cycle. Accordingly, there is a minimum streamflow phase, which takes place from the beginning of the year until May, a relative maximum phase which extends from May through mid-September, when the absolute maximum phase begins until the next minimum phase. Subsequently, streamflow series representative of each phase were examined. All the estimated series showed a breakpoint or step change towards lower streamflow between 2007 and 2010, which induces negative and significant trends, yet spurious. Throughout the homogeneous period before the breakpoint, the series of the different phases showed distinct variability. Regarding the potential forcings, the streamflow of the minimum phase showed an inverse relationship with the Southern Annular Mode (SAM) index and a direct association with the TNA index, which represents the sea surface temperature (SST) variability of the tropical North Atlantic Ocean. The streamflow of the relative maximum phase exhibited a direct relationship with El Niño Southern Oscillation (ENSO) indices and an inverse association with the TSA index of the tropical south Atlantic SST. Lastly, the streamflow of the absolute maximum phase showed a direct relationship with the ENSO and Indian Ocean Dipole indices and an inverse connection with the SAM and TNA indices. These results provide useful insights about the changes in the hydrological regime of the river and its variability, ...