Fresh Water and Karst Topography. Hydrologic cycle On a global basis: Water from atmosphere to earth...
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Transcript of Fresh Water and Karst Topography. Hydrologic cycle On a global basis: Water from atmosphere to earth...
Hydrologic cycleHydrologic cycle
On a On a globalglobal basis: basis:
Water from atmosphere to earth
(Precipitation)
Water from earth to atmosphere
(Evaporation andTranspiration)
=
Surface WaterSurface Water
lakeslakes
streamsstreams
overland flowoverland flow
Ground waterGround water
soilsoil
pores in rockspores in rocks
regolithregolith
sedimentssediments
Ground waterGround water
Water stored beneath the surface, in Water stored beneath the surface, in rock, regolith, soil, sedimentsrock, regolith, soil, sediments
– Flows to surface waterFlows to surface water– Is Is rechargedrecharged (fed) by surface streams (fed) by surface streams
Water percolates downward from soil as Water percolates downward from soil as gravitational water through gravitational water through aerated aerated zonezone; reaches ; reaches water tablewater table, which is the , which is the top of the top of the saturated zonesaturated zone
aquifer:aquifer: rock or sediment that rock or sediment that holds a body of free-flowing holds a body of free-flowing
ground waterground water
Ground water utilization: Ground water utilization:
well pumping causes well pumping causes cone of depressioncone of depression; ;
Karst TopographyKarst Topography
movement of ground water through movement of ground water through limestone produces limestone produces karst karst landscapes.landscapes.
Characteristics:Characteristics: SinkholesSinkholes
CavesCaves SpringsSprings
Lack of surface waterLack of surface water
Requirements:Requirements:(Not all limestone regions are karst regions)(Not all limestone regions are karst regions)
““pure” limestone pure” limestone – (>80% calcium carbonate)(>80% calcium carbonate)
abundant rainfallabundant rainfall complex joint patterns in complex joint patterns in
limestonelimestone
Carbonation process:Carbonation process:
1. carbon dioxide + water 1. carbon dioxide + water carbonic carbonic acidacid
2. carbonic + 2. carbonic + calciumcalcium calciumcalcium
acidacid carbonatecarbonate bicarbonatebicarbonate
in limestone
soluble
Soluble product of the reaction is Soluble product of the reaction is carried away in groundwatercarried away in groundwater
As groundwater seeps through As groundwater seeps through joints, rock is gradually dissolved; joints, rock is gradually dissolved; beginning of cavern formationbeginning of cavern formation
As rock dissolves, surface loses As rock dissolves, surface loses underlying support and subsides or underlying support and subsides or collapses:collapses:
SINKHOLE developsSINKHOLE develops
TravertineTravertine
Calcite that has precipitated out of Calcite that has precipitated out of groundwater as a mineral depositgroundwater as a mineral deposit
carbonation in reverse carbonation in reverse ::
calcium calcium calcite + CO calcite + CO2 2 + + HH22OO
bicarbonatebicarbonatetravertine
Some types of travertine:Some types of travertine:
soda strawssoda straws draperiesdraperies stalactitesstalactites stalagmitesstalagmites columnscolumns