Trends of hydrograph components in rivers of North of Iberian Peninsula during 1972–2012

An analysis of temporal evolution of discharge components was made in 13 rivers located at the North of Iberian Peninsula over the period 1972–2012. Three hydrograph separation methods (PART, HYSEP-LM and BFI) were used to evaluate the trend of baseflow and quickflow. Baseflow represents more than 50% of streamflow on an annual scale in all rivers, except in one of them (Miera River). All rivers of Northwestern part showed a significant negative trend of monthly baseflow, with a mean decrease of 0.6% per year and in Northeastern part most of rivers (4 out of 7) showed a negative trend representing an annual decrease of 2%. In contrast, quickflow increased significantly in five of the 13 rivers studied. The relation of hydrograph components trend and rainfall trend was significant for baseflow in winter, while quickflow was significant for winter and spring. In autumn and summer, no relationship between these trends was detected.