Trends in hydrologic time series

Nowadays it is often mentioned that the Earth is already suffering from climate change effects: it is no longer a matter of future climate scenarios, but rather frequent abnormal climate occurrences. If changes are already happening then they should be embedded in some of the hydrologic time series, with emphasis on those series more closely related to the weather, such as the rainfall series. In the previous scope several studies were carried out aiming at identifying trends in long Portuguese hydrologic time series and at relating such trends with the climate change issue. Some of the models applied for that purpose, as well as some of the results achieved, are briefly summarized. In general terms the studies showed that for the time being the hydrologic time series do not exhibit the trends that are generally pointed out as typifying the climate change effects.