Historical evidences of streamflow fluctuations in the Mendoza River,Argentina,and their relationship with ENSO

Documentary sources are used to construct records of high and low flows of the Mendoza River and to relate these to ENSO over the historical period. The historical data are calibrated against measured discharge (ad 1909–1940) and validated by precipitation discharge-series reconstructed from tree-rings (ad 1600–1960). An increase in the number of high-streamflow events since the mid-seventeenth century is accompanied by several intervals with an above-average number of high-streamflow events; some of these intervals are also characterized by an above-average number of low-streamflow events. A considerable number of high-streamflow events do not coincide with ENSO events, which are regarded as a necessary but not sufficient cause of the extreme streamflow variations.