River‐discharge dynamics in the Southern Central Andes and the 1976–77 global climate shift

Abstract

AbstractRecent studies have shown that the 1976–77 global climate shift strongly affected the South American climate. In our study, we observed a link between this climate shift and river‐discharge variability in the subtropical Southern Central Andes. We analyzed the daily river‐discharge time series between 1940 and 1999 from small to medium mountain drainage basins (102–104 km2) across a steep climatic and topographic gradient. We document that the discharge frequency distribution changed significantly, with higher percentiles exhibiting more pronounced trends. A change point between 1971 and 1977 marked an intensification of the hydrological cycle, which resulted in increased river discharge. In the upper Rio Bermejo basin of the northernmost Argentine Andes, the mean annual discharge increased by 40% over 7 years. Our findings are important for flood risk management in areas impacted by the 1976–77 climate shift; discharge frequency distribution analysis provides important insights into the variability of the hydrological cycle in the Andean realm.