ABSTRACT
Hydrology is no longer limited to the geophysical science of the natural circulation and storage of waters on the earth. This chapter attempts to review some of the evidence available and to provide an insight into the nature and extent of this impact. Faced with the task of highlighting recent trends within the science of hydrology, Ackermann emphasized the need for a greater awareness of the impact of man on hydrological processes and added further support to a view which had become increasingly voiced during the 1960s. Numerous studies, working groups, and symposia resulted from this international activity, and the vast body of evidence and knowledge concerning man's impact on hydrological processes and associated problems that has accumulated, reflect a widespread recognition of the view echoed by Ackermann. Modifications to individual processes will clearly have repercussions throughout the hydrological system and for this reason they are rarely studied in isolation.
