Surface water resources evolution in 4 stream flows tributaries of the Douro river

Abstract

In this work we analyze the surface water resources evolution in four stream flows, tributaries of the Douro river, since the second half of the XX century till the beginning of the XXI. The obtained results show a decrease in the total annual flow of the four rivers, even though this decrease was not statistically significant. This declining tendency is particularly remarkable after 1980.

Except for autumn, in which a slight increase is verified, all the other seasons show regressive tendencies in overland flow, much more accentuated during winter and spring, although in summer, due to the deficit shown by these rivers, situations of high amount scarcity in water resources could be promoted. This annual decline in water resources, especially during the period in which the highest demand and the lowest quantity are registered, must be a subject for reflection, in order to avoid situations of water scarcity.