Fig 1. Rainfall, water flows and volume stored in the Cantareira system since 2004.

Upper panel: notwithstanding the inter-annual trend, a clear seasonal fluctuation is present in the rainfall (gray) which was followed by the volume of stored water (percentage of operational volume, blue line) until mid 2013. From this point on, the volume of water decreased to very low levels, without any seasonal trend. A recovery of small amplitude is seen from Feb-May 2015 due to reduction in outflow. This is shown in the lower panel: the water inflow into the reservoir (gray) showed seasonal fluctuations coupled to rainfall. The reservoir operators kept outflow (blue line) around the maximum average allowed (36 m ³ s ⁻¹, exceeded only to avoid overflow). Operators started a gradual decrease in outflow in the beginning of 2014, when the operational volume was close to depletion. Since the depletion (July 2014), water is available only by pumping, and outflow reduction proceeded in a slow pace till January 2015, when it was abruptly cut by 25%.