The Hydrogeologic Cycle And Its Relationship To Geologic Processes

The concept of the hydrologic cycle, the germ of which was conceived of by Plato and expanded upon by Vitruvius, Palisay, Perrault, Mariotte, Halley, Lametherie and others required more than 2000 years for its acceptance. The physical and chemical factors that govern the state, occurrence, movement, quality and quantity of water in various segments of this cycle are still being clarified 2300 years after Plato advanced his pluvial concept in "Critis's." Man's understanding of the natural laws that operate in the hydrologic cycle and his engineering mastery over them holds the key to his successful evaluation, development, and management of water in all segments of this cycle. Water in the hydrologic cycle serves as an active and passive agent to geologic and other processes and has played a varied and significant role in shaping geologic events. Since water is an intimate agent to geologic processes, it should not be thought of exclusively in the restricted sense of man's economic exploitation of water, his social and aesthetic benefits nor the harassment it causes him due to its overabundance or scarcity. Consideration of the role of water in the hydrologic cycle through geologic time and of water not generally considered part of the hydrologic cycle requires that recognition be given to a second grander cycle - the hydrogeologic cycle — which involves the interaction of earth materials and water under varied environmental conditions from sediment accumulation to tectonics.