Use of Teleconnection Indices for Water Management in the Cantareira System - São Paulo – Brazil

The drought that occurred in 2014/2015 over the Metropolitan Region of São Paulo (MRSP) was considered one of the most intense in the region’s history, causing a crisis in the state of São Paulo’s public water-supply sector. The objectives of this study were: (1) to generate a hydroclimatological baseline for the Cantareira System region; (2) to evaluate the local potential relationship between teleconnections based on global climatic indices and rainfall/flow anomalies; and (3) to propose a tool to assist in the management of the MRSP’s largest water-production system. Precipitation and natural-flow data in the Cantareira System for 1948–2015 were used in this study. The evaluated teleconnection indices included the Oceanic Niño Index (ONI), Antarctic Oscillation (AAO), Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation (NAO). We verified that these indices were more sensitive on a seasonal scale to the occurrence of excess rainfall and flow events than drought events. For the ONI and AAO positive phases, the Cantareira System’s flow was above-average in summer and winter, which is associated with flood events. The AAO’s negative phase was associated with deficit events in summer and winter, but not extreme deficit events. The PDO’s positive phase was associated with flood events in winter and spring. The results from this study could be used as an additional climatic tool for managing the Cantareira System through the monitoring of average flows and seasonal indices.