GroundwaterGroundwater

Water that soaks into Water that soaks into the ground after rainthe ground after rain

Factors that Factors that determine the determine the amountamount Steepness of slopesSteepness of slopes Type of surface Type of surface

materialsmaterials Intensity of rainfallIntensity of rainfall Type and amount of Type and amount of

vegetation vegetation

Distribution of GroundwaterDistribution of Groundwater

Belt of Soil Moisture – water that covers the top of Belt of Soil Moisture – water that covers the top of the soilthe soil

Roots, openings from decayed roots, animal burrowsRoots, openings from decayed roots, animal burrows Zone of Aeration – area above the water table that Zone of Aeration – area above the water table that

contains air in between soil particlescontains air in between soil particles Zone of Saturation – open spaces in the soil fill with Zone of Saturation – open spaces in the soil fill with

water (groundwater) that can be extracted by wellswater (groundwater) that can be extracted by wells Water Table – boundary between the zone of Water Table – boundary between the zone of

aeration and zone of saturationaeration and zone of saturation

Porosity and PermeabilityPorosity and Permeability

Porosity – the amount of Porosity – the amount of water that can be stored water that can be stored in the pore spaces in the in the pore spaces in the rock or sediments rock or sediments

Joints, faults, and caverns Joints, faults, and caverns are includedare included

Permeability – a material’s Permeability – a material’s ability to release waterability to release water

If pore spaces are too small, If pore spaces are too small, the water cannot pass the water cannot pass through - impermeablethrough - impermeable

AquifersAquifers Aquitard – formed Aquitard – formed

by impermeable by impermeable materials that materials that create a zone of create a zone of saturation above itsaturation above it

Aquifer – permeable Aquifer – permeable layers that allow layers that allow water to flow freely water to flow freely throughthrough The source of most The source of most

water wellswater wells

Springs and GeysersSprings and Geysers Spring – groundwater that Spring – groundwater that

emerges naturally from the emerges naturally from the ground surfaceground surface

Hot Springs – have a Hot Springs – have a temperature that is 6-9temperature that is 6-9ooC C warmer than average air warmer than average air temperature; heated by heat temperature; heated by heat flow from magmaflow from magma

Geyser – hot spring that Geyser – hot spring that shoots water up from the shoots water up from the ground periodicallyground periodically

Water is heated by heat flow Water is heated by heat flow from magma from magma water expands water expands creates pressure creates pressure forces forces water out of the groundwater out of the ground

WellsWells

A hole drilled into the zone of saturation for the purpose A hole drilled into the zone of saturation for the purpose of extracting waterof extracting water

65% of wells are for agricultural irrigation in the United States65% of wells are for agricultural irrigation in the United States The well must extend below the water table to account for the The well must extend below the water table to account for the

periodic rise and fall of the water levelperiodic rise and fall of the water level Cone of depression – lowering of the water table around a well Cone of depression – lowering of the water table around a well

due to large amounts of water being pumped outdue to large amounts of water being pumped out Artesian Well – the water in the ground rises under its Artesian Well – the water in the ground rises under its

own pressureown pressure

Groundwater OveruseGroundwater Overuse

Groundwater is Groundwater is replenished mostly by replenished mostly by rainrain If there is less rain than If there is less rain than

use of the water, the use of the water, the water level will water level will decreasedecrease

If the water use is If the water use is stopped, it may take stopped, it may take thousands of years to thousands of years to completely replenish completely replenish the groundwaterthe groundwater

Groundwater Overuse Groundwater Overuse (cont’d)(cont’d)

Ground Ground subsidencesubsidence (sinking) can occur if (sinking) can occur if water is used faster than water is used faster than it is replenishedit is replenished Creates depressions or Creates depressions or

sinkholessinkholes Leads to Leads to karst topographykarst topography

(leads to irregular terrain (leads to irregular terrain with various sinkholes)with various sinkholes)

Found in Kentucky, Found in Kentucky, Tennessee, Alabama, Tennessee, Alabama, southern Indiana, and southern Indiana, and northern Floridanorthern Florida

Sources of Groundwater Sources of Groundwater ContaminationContamination Sewage from septic tanks, farm wastes, inadequate or Sewage from septic tanks, farm wastes, inadequate or

broken sewersbroken sewers Fertilizers and pesticides from agricultureFertilizers and pesticides from agriculture Residential runoffResidential runoff Highway saltsHighway salts Chemical and industrial materials that leak from Chemical and industrial materials that leak from

pipelines, storage tanks, landfills, or holding tankspipelines, storage tanks, landfills, or holding tanks Saltwater in coastal areasSaltwater in coastal areas Minerals and nutrients from dissolved rock and other Minerals and nutrients from dissolved rock and other

natural materialsnatural materials

Types of Groundwater PollutionTypes of Groundwater Pollution

Point Source Pollution – Point Source Pollution – contaminants have an contaminants have an identifiable sourceidentifiable source Smokestacks, car Smokestacks, car

tailpipetailpipe Nonpoint Source Nonpoint Source

Pollution – contaminant Pollution – contaminant source cannot be foundsource cannot be found Several farmlands in the Several farmlands in the

same areasame area

Contaminant SpreadingContaminant Spreading Flow downhill – contaminants leaked into the Flow downhill – contaminants leaked into the

ground at the top of a hill will flow downhill ground at the top of a hill will flow downhill Rainwater – runs through the contaminant, Rainwater – runs through the contaminant,

absorbs it, and transfers it to another areaabsorbs it, and transfers it to another area

Groundwater CleaningGroundwater Cleaning If water travels slowly If water travels slowly

through sand or through sand or permeable sandstone, permeable sandstone, the water is purified the water is purified

Sometimes Sometimes contaminated water is contaminated water is pumped out of an pumped out of an aquifer and treated; the aquifer and treated; the aquifer is replenished aquifer is replenished naturally or with the naturally or with the treated watertreated water

AssignmentAssignment

A Snapshot In A Snapshot In TimeTime