The hydrochemical facies evolution diagram (HFE-D) was applied to the data from an alluvial aquifer on the East Coast of Spain (Vinaroz-Pe˜n´ıscola Plain; Figures 2a and 2b) where samples were taken in both summer and winter. The samples collected in summer generally correspond
to hydrochemical facies that indicate a generalized sea water intrusion through the aquifer, while the winter samples indicate that certain parts of the aquifer are in a phase of recovery related to the recharge water. The presence of water with a sulfate facies indicates that the
recharge water can be either bicarbonate or sulfate type.