DEFINITIONS

Hydrologic Cycle:  Also known as the water cycle, this refers to the paths water moves through in its various states–vapor, liquid, and solid–as it moves throughout Earth's systems (oceans, atmosphere, groundwater, streams, etc.).

Aquifer: An underground bed of saturated soil or rock that yields significant quantities of water.

Groundwater: Water found in spaces between soil particles underground (located in the zone of saturation).

TO DO

Have students participate in the Great Swamp Incredible Journey activity (Appendix 1) to learn how water moves through the Great Swamp watershed.

2. The Water Cycle

The Earth’s supply of fresh water is a precious, and very limited, resource. Although 75% of the Earth’s surface is covered by water, less than 3% of that water is fresh, and only one half of one percent is readily accessible for human use.

Water continuously moves from the atmosphere to the land to the oceans and back to the atmosphere in what is known as the Hydrologic Cycle. After precipitation falls (in the form of rain, snow or ice), it may immediately evaporate from the ground, plants and trees, or water bodies back into the air. A small percentage will run off into streams and rivers, eventually making its way to the oceans. Most of the water soaks into the ground, where it either replenishes shallow aquifers that sustain streams and springs, or seeps into deeper aquifers that serve as large underground reservoirs of freshwater. Water may remain in deep aquifers for centuries, gradually moving toward and into the sea, where it evaporates again into the atmosphere.

Source: Project WET: Curriculum and Activity Guide

Despite the fact that water is constantly moving through the hydrologic cycle and thus being recycled in a sense, it is not necessarily being returned to its prior pristine state. Humans interfere with the basic processes of the water cycle in a number of ways. These interferences include depleting groundwater supplies for drinking water, agriculture and other human needs, paving over the land surface, and releasing pollutants into local streams. Once polluted or degraded, it is very difficult to restore water to the standards that must be met for human consumption. Thus pollution prevention is the most efficient and effective way to protect our water quality.

Copyright 2000. Great Swamp Watershed Association.