Influence of Pacific Ocean multidecadal variability on the distributional properties of hydrological variables in north-central Chile

- We analyze PDO and ENSO relationship with precipitation and streamflow records.
- Streamflows show regime shift consistent with that of PDO.
- Precipitation does not show regime shift.
- Streamflow distributional properties are related with PDO phases.
- Under PDO cool phase, mean annual streamflow is always lower than that for warm PDO.

SummaryThis paper addresses the relationship between multitemporal variability and regime shifts in the Pacific Decadal Oscillation and El Niño Southern Oscillation, with precipitation and streamflows in Andean watersheds of the north-central region of Chile. In addition, an analysis of the effect of a regime shift displayed by annual streamflow records on their distributional properties is performed. By applying empirical fluctuation processes to monthly standardized PDO, Niño 3.4, precipitation and streamflow time series, the occurrence of a regime shift in the streamflow series, consistent with that for PDO, but highly dependent on the latitude of particular watersheds, is shown. No regime shift is detected for the precipitation time series. Using the ensemble Empirical Mode Decomposition procedure on all series, a relationship between climatic indices and hydrological variables in two main modes is determined: the former associated with a mean period of quasi 1.5-3 years related to interannual variability, and the latter with a mean period of quasi 30-35 years, related to decadal low frequency variability. Using the regional frequency analysis based on the L-moments procedure, it is found that the distributional properties of streamflow records are influenced by the phases of the PDO, with changes that affect the mean, L-CV, L-skewness and L-kurtosis in three identified homogeneous regions. The importance of incorporating low-frequency climate variability for distributional analysis and the implications of these results for water resources management and planning in north-central Chile and similar areas is discussed.