The International Hydrological Decade (which ended in 1975) led to a revival of hydrological sciences to a degree which, seen in retrospect, is quite spectacular. This research programme had strong government support, no doubt due to an increased awareness of the role of water for prosperous development. Since water quality is an essential ingredient in almost all water use, there was also a considerable interest in hydrochemistry during the Decade. As many concepts in classical hydrology had to be revised during and after the Decade there was also a need for revising hydrochemistry to align...