Chapter 14-1 Groundwater

Pages 298-315Geology

GroundwaterFactors that affect the amount of seepage of water into the ground are:Type of rock or soil on the ground where the water falls

Climate, topography, land use, vegetation

PorosityThe percent of a materials volume that is pore space the more the space, the more water that can be held.Depends on: Particle shapeMore rounded particles allows for more pore spacesSortingWell sorted material (same size) offers greatest pore spaces

PermeabilityThe rate at which water or other liquids pass through the pore spaces of a rock.Permeability increases with grain sizeEx: sand and gravel is highly permeable while clay and shale has low permeability.

So, can a rock be highly porous but not be permeable? explain

Or, can a nonporous rock become highly permeable?

The water tableThe water table is the upper surface of the zone of saturation

Above this level up to the surface, the ground can still hold more water, and this area is called the zone of aerationThis zone of aeration contains 3 parts:

The three parts of the zone of aeration are:1) capillary fringeFound just above the water table, where water rises due to waters attraction to the soil particles.This is called Capillary action2) a dry region of soil except after rainfall3) organic or humus layer just below the surface

What are some factors that affect the depth of the water table

How is the water table important?Seepage from water table keeps streams flowing between rain eventsMaintains water levels of lakes and wetlandsProvides drinking water from natural springs and human-made wells

Types of wellsOrdinary wellWater must be pumped out of the wellArtesian wellWell water is under some pressure to force the water up the well does not have to be to the top.

Large volumes of water found underground in the pore spaces is called an aquifer.***best aquifers are those made of uncemented sands and gravel, followed by porous sandstones.

View of an artesian formation

How does a geyser occur?Geyser animation

Conserving Groundwater- Water BudgetsChapter 14-2Pages 306-307

Water budgetDescribes the income and spending of water for a region.The income is rain or snowThe spending includes water loss by use, runoff, and by evapotranspiration.Weather is the controlling factor of evapotranspiration- when temperatures are high, the amount of evapotranspiration would also increase.- the opposite is also true, low temperature causes low evapotranspiration.

Four parts of a water budgetRechargeWhen moisture is added to the groundwater, the soil water storage is fillingSurplusOccurs when the rainfall is greater than the need for moisture, and the storage water is filledUsageIf the need for moisture is greater than the rainfall and the plants draw water from the soil water supplyDeficitOccurs when the need for moisture is greater than the rainfall and the soil water is gone.

Examples of water budget

Another water budget example

Water conservationIn many regions, water is being used at a faster rate than can be naturally replenished.

Pollution is also threatening many groundwater supplies

Percent water consumption

Overuse of groundwaterWhen groundwater supplies are depleted, the water table dropsThis may cause wells, springs to go dry

If this happens along coastal regions, salt water may seep into overused freshwater aquifers and damage water supplies by making them salty and unusable.

Overuse of groundwater may cause ground levels to drop due to compaction of the removal of groundwater below.Entire valleys may subside like the San Joaquin Valley of California (up to 30 feet drop from 1925-1977)!

Sinkholes may formfrom loss of groundwater

In Bowling Green, KYIn Florida

Groundwater pollutionGroundwater may become polluted by human activities:FertilizerOil from roadwaysPesticidesSewage from septic tanks and sewersHazardous wastes from industryToxic waste dumps (Love Canal New York)

Images of Love Canal

Groundwater and GeologyChapter 14-3Pages 309-311

Geologic formations formed by groundwaterGroundwater moving through bedrock may take in dissolved minerals.This water is now called hard water.Calcium ions is most common mineral in hard H2O

What do we do at home to reduce hard water?

Hard water causes water spots, poor washingArtesian water is usually harder than regular groundwaterGroundwater is almost always harder than river water

Mineral depositsWhen water evaporates or cools, it will leave behind any minerals that were dissolved in the water.Examples: geyserite, geodes, mineral veins of copper, quartz, gold, silver, calcite, etc.

Petrified wood is formed when minerals replace decaying wood of buried treesCalcite is most common dissolved mineral cement for grains of sand and pebbles.

Mineral springsA spring with a high concentration of mineral matterMay be due to:Hot waterWater passes through easily dissolved mineralsWater contains large quantity of gasesSome mineral springs areas have become health resorts Hot Springs, ArkansasYellowstones Mammoth Hot Springs forms calcium deposits called traventine

CavernsFormed in areas with limestone bedrockLimestone is dissolved by carbonic acid found in the groundwaterDripstone StalactitesStalagmitesWhen they meet, they form columns or pillars

Examples include Mammoth Cave in Kentucky, caves of Calumet and Door County, WI, Eagle Cave west of Madison

Karst TopographyIdentified by sinkholes, sinkhole ponds, fissures, lost rivers, and underground riversCreated when caverns collapseForms where bedrock is made of calcite or dolomiteFound in south-central Kentucky, Door County, WI