GROUNDWATER & AQUIFERS IN THE MIAMI VALLEY
Groundwater is one segment of the natural system known as the hydrologic cycle. This complex cycle consists of the many pathways a droplet of water may take on its journey between the land, sea, and atmosphere.
- The Hydrologic (or Water) Cyle
Water is moved through the hydrologic cycle by the processes of precipitation, evaporation, plant transpiration, infiltration and runoff. Some of the water that falls to the earth as rain may run off the land surface and enter into lakes, streams, and the oceans. Some of it may evaporate immediately from the land surface or enter the soil where it may be absorbed and transpired back to the atmosphere by plants.
A fraction of the water that falls upon the land surface infiltrates into the soil and percolates downward through the open pore spaces between the soil and rock particles. Eventually this water reaches the water table below which is a saturated zone where all the pore spaces are filled with water. The water in this zone is called groundwater. A soil or rock formation that is capable of storing, transmitting, and yielding groundwater to wells is called an aquifer. Aquifers serve as underground reservoirs from which quantities of groundwater can be withdrawn.
- Groundwater is stored in aquifers.
The groundwater in an aquifer is in a constant state of change. The level of the water table and the amount of water present continuously fluctuate with the amount of water entering and leaving the aquifer. Water that enters and replenishes the aquifer is called recharge. Water that leaves the aquifer is called discharge. The amount and rate of recharge and discharge are governed by a variety of natural factors related to soil type, streamflow, climate, geology, topography, and vegetation as well as a number of man-made factors such as groundwater pumping, urbanization, and land use.