Chapter 14 1 groundwater
Sponsored Links
This presentation is the property of its rightful owner.
1 / 38

Chapter 14-1 Groundwater PowerPoint PPT Presentation


  • 132 Views
  • Uploaded on
  • Presentation posted in: General

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.

Download Presentation

Chapter 14-1 Groundwater

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


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

  • 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

  • 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 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:


  • 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


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 events

  • Maintains water levels of lakes and wetlands

  • Provides drinking water from natural springs and human-made 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


How does a geyser occur?

  • Geyser animation


Conserving Groundwater- Water Budgets

Chapter 14-2

Pages 306-307


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

  • 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


Another water budget example


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


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.


  • 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, KY

  • In Florida


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


Groundwater and Geology

Chapter 14-3

Pages 309-311


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

    • 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

    • 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

    • 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

    • 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


  • Login