http://www.linkplug.com/science_and_technology/hydrology/LinkPlug! is about providing a directory of quality sites for world wide web users. Our goal is to list the best sites for a wide variety of topics giving our users the most relevant results for their searches. The hydrologic cycle is a constant movement of water above, on, and below the earth's surface. It is a cycle that replenishes ground water supplies. A practitioner of hydrology is a hydrologist, working within the fields of either earth or environmental science.