Climate changes impacts in the upper Paiva River: today and in the future

The Paiva River is a tributary of the Douro River in northern Portugal with a length of 110 km and a catchment area of 790 km(2). Nowadays, its upper section dries completely by the end of the dry season every year. The individuals living in communities along the river are consistent in identifying the beginning of this phenomenon by the end of the 1990 s or early 2000 s. In the present research, the potential causes for this are identified, evaluated, and discussed. The direct human consumption was possible to exclude due to the decrease of both population and water-intensive activities in the period of interest. Considering the information available, climate changes are identified as the main driver for the complete dry out of the upper section. Specifically, the differences in the precipitation distribution along the year were found to be statistically significant and the increase of the number of consecutive days without rain could be related to the depletion of the underground water. Considering rainfall pattern forecasts for 2050 based on various climate change scenarios and global circulation models, it is possible to conclude that the already poor environmental condition of the upper Paiva River section will degrade even further in the future.