Interannual-to-multidecadal Hydroclimate Variability and its Sectoral Impacts in northeastern Argentina

Abstract

This study examines the joint variability of pre- cipitation, river streamflow and temperature over northeast- ern Argentina; advances the understanding of their links with global SST forcing; and discusses their impacts on water re- sources, agriculture and human settlements. The leading pat- terns of variability, and their nonlinear trends and cycles are identified by means of a principal component analysis (PCA)complemented with a singular spectrum analysis (SSA). In- terannual hydroclimatic variability centers on two broad fre- quency bands: one of 2.5?6.5 years corresponding to El Niño Southern Oscillation (ENSO) periodicities and the second of about 9 years. The higher frequencies of the precipita- tion variability (2.5?4 years) favored extreme events after 2000, even during moderate extreme phases of the ENSO. Minimum temperature is correlated with ENSO with a main frequency close to 3 years. Maximum temperature time se- ries correlate well with SST variability over the South At- lantic, Indian and Pacific oceans with a 9-year frequency. Interdecadal variability is characterized by low-frequency trends and multidecadal oscillations that have induced a tran- sition from dryer and cooler climate to wetter and warmer decades starting in the mid-twentieth century. The Paraná River streamflow is influenced by North and South Atlantic SSTs with bidecadal periodicities.The hydroclimate variability at all timescales had signif- icant sectoral impacts. Frequent wet events between 1970 and 2005 favored floods that affected agricultural and live- stock productivity and forced population displacements. On the other hand, agricultural droughts resulted in soil mois- ture deficits that affected crops at critical growth stages. Hy-drological droughts affected surface water resources, caus- ing water and food scarcity and stressing the capacity for hydropower generation. Lastly, increases in minimum tem- perature reduced wheat and barley yields.