GROUND WATER LECTURE NOTES

VOCABULARY: hydrologic cycle, evapotranspiration; glaciers; ground water; soil moisture; water vapor; meteoric water, connate water; magmatic water; juvenile water; permeability; porosity; impermeable; gradient; well; drawdown; cone of depression; artesian well; subartesian well; recharge; cap rock; aquifer; aquiclude; spring; hot spring; geyser; karst topography; carbonation; cavern; sinkhole; disappearing stream; stalactite; stalagmite; youth; late youth; maturity; old age; haystack hills

HYDROLOGIC CYCLE

agent--GROUND WATER
process--solution

ground water--the water contained in the ground and moving through it

composed of:

• meteoric water--soaks into the ground
• connate water--trapped in sediments when formed
• magmatic water (juvenile water)--given off by cooling magmas

usually ground water sinks until solid or impermeable layer, backs up above it, becomes saturated, forms water table
water may flow within the permeable layer

GROUND WATER

permeability--rate at which water passes through a porous material like soil or rock
porosity--amount of space between grains in a rock

depends on:

• sorting or uniformity of particles
• packing arrangement of particles in a mass
• grain shape--rounded, irregular
• extent of cementation

permeability varies:

• loose--usually very permeable
• granular rocks, more than shale or limestone
• dense rocks (igneous, metamorphic) only if fractures or joints

rate (speed) of flow--2 factors:

• gradient or slope
• permeability of rock

IF both HIGH, several FEET per day
level of water table varies according to amount of rainfall; wet weather, rises near surface and conforms to it; dry weather, sinks, almost level
wells--holes dug or drilled below water table
any well drilled in permeable rock usually will supply water
shallow wells may dry up during dry season, may be pumped dry
igneous and metamorphic must be jointed or fractured, deeper, fewer cracks

cone of depression--three dimensional lowering of the water table around an active well
drawdown--vertical depression of the water table in an active well

artesian well--exception, relies on water from another area, an impermeable rock is necessary; free flowing
subartesian well--needs to be pumped part way
spring--ground water naturally coming to surface


ground water is cool because the sun's rays do not penetrate that deep
hot springs and geysers--subsurface volcanic activity
geyser--steam collects in a pocket within earth, heat, boil, expand, steam in air


KARST--an adjective to describe the topography which results from solution of the bedrock
karst topography--the result of the form of weathering by carbonation

cavern--ground water channel excavation
sinkhole--result of cavern roof collapse
disappearing stream--stream flowing into a sinkhole
stalactite--evaporite deposit hanging down from roof of cavern
stalagmite--evaporite deposit sticking up from floor of cavern

youth--few sinks, smooth
late youth--more
maturity--cavern collapse, irregular
old age--little limestone remaining, haystack hills

Go to the Karst Block

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Go to the Ground Water Review Questions

Go to the Glossary of Landform Terms

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