Chapter 14 1 groundwater
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Chapter 14-1 Groundwater. Pages 298-315 Geology. Groundwater. Factors 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. Porosity.

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Chapter 14-1 Groundwater

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Chapter 14 1 groundwater

Chapter 14-1 Groundwater

Pages 298-315

Geology


Groundwater

Groundwater

Factors 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


Porosity

Porosity

  • The percent of a materials volume that is pore space – the more the space, the more water that can be held.

  • Depends on:

    • Particle shape

      • More rounded particles allows for more pore spaces

    • Sorting

      • Well sorted material (same size) offers greatest pore spaces


Permeability

Permeability

  • The rate at which water or other liquids pass through the pore spaces of a rock.

    • Permeability increases with grain size

    • Ex: 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 table

The water table

  • The 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 aeration

    • This zone of aeration contains 3 parts:


Chapter 14 1 groundwater

  • The three parts of the zone of aeration are:

    • 1) capillary fringe

      • Found just above the water table, where water rises due to water’s attraction to the soil particles.

      • This is called Capillary action

    • 2) a dry region of soil except after rainfall

    • 3) organic or humus layer just below the surface


Chapter 14 1 groundwater

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


How is the water table important

How is the water table important?

  • Seepage from water table keeps streams flowing between rain events

  • Maintains water levels of lakes and wetlands

  • Provides drinking water from natural springs and human-made wells


Types of wells

Types of wells

  • Ordinary well

    • Water must be pumped out of the well

  • Artesian well

    • Well 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

View of an artesian formation


How does a geyser occur

How does a geyser occur?

  • Geyser animation


Conserving groundwater water budgets

Conserving Groundwater- Water Budgets

Chapter 14-2

Pages 306-307


Water budget

Water budget

  • Describes the income and spending of water for a region.

    • The income is rain or snow

    • The 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 budget

Four parts of a water budget

  • Recharge

    • When moisture is added to the groundwater, the soil water storage is filling

  • Surplus

    • Occurs when the rainfall is greater than the need for moisture, and the storage water is filled

  • Usage

    • If the need for moisture is greater than the rainfall and the plants draw water from the soil water supply

  • Deficit

    • Occurs when the need for moisture is greater than the rainfall and the soil water is gone.


Examples of water budget

Examples of water budget


Another water budget example

Another water budget example


Water conservation

Water conservation

  • In 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

Percent water consumption


Overuse of groundwater

Overuse of groundwater

  • When groundwater supplies are depleted, the water table drops

    • This 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.


Chapter 14 1 groundwater

  • 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 form from loss of groundwater

Sinkholes may formfrom loss of groundwater


Chapter 14 1 groundwater

  • In Bowling Green, KY

  • In Florida


Groundwater pollution

Groundwater pollution

  • Groundwater may become polluted by human activities:

    • Fertilizer

    • Oil from roadways

    • Pesticides

    • Sewage from septic tanks and sewers

    • Hazardous wastes from industry

    • Toxic waste dumps (Love Canal – New York)


Images of love canal

Images of Love Canal


Groundwater and geology

Groundwater and Geology

Chapter 14-3

Pages 309-311


Geologic formations formed by groundwater

Geologic formations formed by groundwater

  • Groundwater 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 washing

  • Artesian water is usually harder than regular groundwater

  • Groundwater is almost always harder than river water


  • Mineral deposits

    Mineral deposits

    • When 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 trees

    • Calcite is most common dissolved mineral cement for grains of sand and pebbles.


    Mineral springs

    Mineral springs

    • A spring with a high concentration of mineral matter

      • May be due to:

        • Hot water

        • Water passes through easily dissolved minerals

        • Water contains large quantity of gases

    • Some mineral springs areas have become health resorts – Hot Springs, Arkansas

    • Yellowstone’s Mammoth Hot Springs forms calcium deposits called traventine


    Caverns

    Caverns

    • Formed in areas with limestone bedrock

    • Limestone is dissolved by carbonic acid found in the groundwater

      • Dripstone

      • Stalactites

      • Stalagmites

        • When 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 topography

    Karst Topography

    • Identified by sinkholes, sinkhole ponds, fissures, lost rivers, and underground rivers

    • Created when caverns collapse

    • Forms where bedrock is made of calcite or dolomite

    • Found in south-central Kentucky, Door County, WI


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