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Last Update: 26 Jun 2018
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Hydrologic CycleHydrologic Cycle
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HYDROLOGIC CYCLE

Hydrology may be defined as the science of the occurrence, movement and control of water in all its natural forms, vapour, liquid and solid, whether occurring in the air, on the surface of the earth or underground. The hydrologist, accordingly, must be a person of many parts, possessing a knowledge of hydraulics, physics, meteorology, mathematics, geography and geology and the ability to foresee the technical requirements for the observation of relevant natural phenomena in the field. Every phenomenon is unique; an observation missed is an observation lost forever.

The physical phenomena with which the hydrologist is concerned are best conceived in terms of the "hydrologic cycle". Water, in all its natural forms, is in constant circulation. The simplest example of such circulation, the cloud-rain-river-sea-cloud cycle, is one facet of the hydrologic cycle. It will be appreciated that there are many other paths both shorter and longer that water may take in completing a cycle. The hydrologic cycle embraces all these paths and the hydrologist is concerned primarily with quantitative observations of the water movement along each of the various paths.