Dr. R. B. Schultz
Groundwater is water, which originates from the infiltration of fluids through
the soil profile and accumulates below the earth's surface in a porous layer.
Porosity is the percentage of open void space in the subsurface material. It is
expressed as a percent.
Permeability is how readily a fluid can flow through a material. Often referred
to as "connected pore space".
Pieziometric surface is the surface in which water is pushed up to by the
Spring is where water flows out without the aid of pumping. It may be caused
by hydrostatic pressure (pressure pushing upward), or the intersection of
the pieziometric surface with the ground surface. Also referred to as an
An aquifer is the porous unit or layer of rock that is able to store or hold
water and transmit enough fluid to be of economic value.
An aquitard is rock material that is low in porosity/permeability. Fluid flow is
not good and the unit may often be termed a "cap rock", not allowing
underlying water to flow upward.
Flowing or Artesian Well Development
An aquiclude is a unit of rock or layer of rock, which is impermeable to fluids.
It acts as a barrier to fluid flow. There probably are no true aquicludes.
There are two (2) scenarios that may occur with aquifers:
1. Confined Aquifer -- when an aquifer is bounded by two (2) aquitards (one
above and one below)
2. Unconfined Aquifer -- when an aquifer is not bounded on the surface side
by an aquitard so that fluids may flow freely above the aquifer.
The distribution of groundwater is present in several distinct layers or zones:
a. Soil moisture zone -- usually top soil; much infiltration; much organic
b. Zone of aeration (Vadose Zone) -- mostly air but some interstitial water
c. Capillary fringe -- transition between unsaturated and saturated zone; top
d. Zone of saturation (Phreatic Zone) -- pores completely saturated with
water; main aquifer storage zone
Where does water in the ground originate?
Hydrologic Cycle explains the origin of groundwater.
Depicts the occurrence and movement of water in the earth-atmosphere
Water enters the GW system at recharge areas.
Water leaves GW system at discharge areas.
Occurrence of water
1. 97% of all water on earth is in oceans.
2. ~ 2% of the earth's water in ice caps & glaciers
3. About 0.6% of earth's water is groundwater
Water in rivers, lakes, and the atmosphere amounts to less than 0.02%
of earth's water
Movement of Water
Atmosphere to surface: precipitation
Surface to atmosphere: evaporation -- liquid to vapor
Sublimation -- solid to vapor
Transpiration -- release of water vapor by plants
On surface: downslope movement to lakes, streams, and oceans
Below surface: movement of groundwater
If GW seeps into stream, stream is a gaining stream.
If water seeps from stream into subsurface, it is a losing stream.
In areas in which soluble rock (i.e., limestone) is present in the layer near the
groundwater, a situation often develops that is characterized by rock layer
dissolving. This is referred to as karst topography.
Indiana, Kentucky, and Georgia are areas in which karst topography may develop.
The area is characterized by:
• a. Soluble bedrock near the surface
• b. Disappearing streams that feed downward with no end on the surface
• c. Sinkholes
• d. Patchy, pockmarked surface topography
• e. Frequent fluctuations in water table
• f. Caves
• g. Submerged caves
Caves are formed by the dissolving nature of the rock fed by groundwater. Large
cavities develop as well as solid drops of rock that precipitate from the
Those overhead are called stalactites (stick tight to the ceiling) and those that
build up from the ground floor are termed stalagmites (with a ''g'').
There are several problems, which can develop, associated with the lowering of
the groundwater surface due to overuse/over pumping:
• 1. Cone of depression develops
• 2. Lowering of the pieziometric surface, thus wells dry up
• 3. Saltwater incursion/intrusion if near an ocean
Contamination results in a decline in water quality.
Nitrates Sewage, Fertilizers, Feedlots
Pesticides, herbicides Agriculture, lawn care
Organic chemicals Industrial wastes, landfills, spills/leaks of fuels
Metals Industrial processes
Brines Oil production
Protecting groundwater resources
• Apply agricultural chemicals properly
• Build better landfills
• Regulate disposal of hazardous materials
• Regulate underground storage tanks (USTs)
• Limit contaminant levels in drinking water supplies.
Cone of Depression Development
Development of Contamination in Groundwater
Permeability Pieziometric surface
Spring Artesian system
Aquiclude Confined aquifer
Unconfined aquifer Soil moisture zone
Vadose zone Phreatic zone
Zone of aeration Zone of saturation
Capillary fringe Hydrologic cycle
Recharge area Discharge area
Sublimation Gaining stream
Losing stream Karst topography
Cone of depression Saltwater intrusion/incursion
Pertinent Web Sites
Good information, photos, and links related to geysers.
Carlsbad Caverns National Park
Home page of Carlsbad Caverns National Park.
World cave database sorted by depth, length, and country.
An extensive listing of cave links from the National Speleological Society.
Caves and Karst Links (Houghton Mifflin)
Links to several cave and karst sites, including class lecture notes, arranged by topic.
Information on show caves in the United States.
Information on caving from the Great Outdoor Recreation Pages (GORP) site.
Edwards Aquifer, Texas
The Edwards aquifer in Texas is a unique groundwater system and one of the most prolific artesian aquifers in the world.
Online groundwater calculators from LMNO Engineering, Research, and Software, Ltd.
The Groundwater Foundation is dedicated to informing the public about one of our greatest hidden resources, groundwater.
Groundwater Issues and Resources
Links to several groundwater and groundwater issue sites.
Groundwater Links (Houghton Mifflin)
Links to several groundwater sites, including class lecture notes, arranged by topic.
Groundwater Links (NAGT)
An extensive listing of groundwater links arranged by topic from the National Association of Geology Teachers (NAGT).
A good basic introduction to groundwater from the Environmental Protection Agency (EPA).
This Central Michigan University site maintained by Dr. Mark Francek lists several good links to Web sites containing
information relative to topics discussed in the chapter.
National Ground Water Association
The mission of the National Ground Water Association is to provide professional and technical leadership in the advancement
of the ground water industry and in the protection, the promotion, and the responsible development and use of ground
National Speleological Society (NSS)
The NSS was founded for the purpose of advancing the study, conservation, exploration, and knowledge of caves.
Great information on how groundwater exists, where it exists, and how it moves.
The Virtual Cave has collected images from around the world and combined them to generate an 'ideal' cave—one that
contains an example of every major type of speleothem, or secondary mineral deposit.
Water Resource Terms (Glossary of)
A glossary of water resource terms from the Edwards aquifer home page.