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					Groundwater




              Dr. R. B. Schultz
                              Groundwater
 
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".
                            space
 
Pieziometric surface is the surface in which water is pushed up to by the
    pressure below.
 
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
    Artesian System.
 
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
      material
b.     Zone of aeration (Vadose Zone) -- mostly air but some interstitial water
c.      Capillary fringe -- transition between unsaturated and saturated zone; top
      of aquifer
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
      system.
 
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.
 
                          Hydrologic Cycle




                                       Precipitation

              Precipitation
Evaporation

                              Runoff
                                               Infiltration
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
    groundwater solution.
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

Groundwater Contamination
Contamination results in a decline in water quality.

Common contaminants:
  Types                                                       Sources
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
                     Key Terminology

Groundwater                   Porosity
Permeability                  Pieziometric surface
Spring                        Artesian system
Aquifer                       Aquitard
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
Precipitation                 Transpiration
Evaporation                   Runoff
Sublimation                   Gaining stream
Losing stream                 Karst topography
Stalagmites                   Stalactites
Cone of depression            Saltwater intrusion/incursion
                                                Pertinent Web Sites
About Geysers
      Good information, photos, and links related to geysers.
  
Carlsbad Caverns National Park
      Home page of Carlsbad Caverns National Park.


Cave Database
      World cave database sorted by depth, length, and country.


Cave Links
      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.


Caves Directory
      Information on show caves in the United States.


Caving Links
      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.


Groundwater Calculations
      Online groundwater calculators from LMNO Engineering, Research, and Software, Ltd.


Groundwater Foundation
      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).


Groundwater Primer
      A good basic introduction to groundwater from the Environmental Protection Agency (EPA).


Karst Links
      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
          water resources.


National Speleological Society (NSS)
      The NSS was founded for the purpose of advancing the study, conservation, exploration, and knowledge of caves.


Understanding Groundwater
      Great information on how groundwater exists, where it exists, and how it moves.


Virtual Cave
      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.

				
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