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GSC1620 Chapter 11. Resources Overview and Water as a Resource. Resources (Background). Earth resource – any valuable or useful commodity extracted from the Earth

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Gsc1620 chapter 11

GSC1620 Chapter 11

Resources Overview and Water as a Resource

Resources background
Resources (Background)

  • Earth resource – any valuable or useful commodity extracted from the Earth

  • Resources can be classified into various categories including: reserves, subeconomic resources, hypothetical resources, and speculative resources

  • Reserves – identified resources that are profitable to extract


  • Subeconomic resources – identified resources that are currently unprofitable to remove

  • Note: the classification of resources as reserves or subeconomic resources can change if the commodity price fluctuates significantly


  • Hypothetical Resources – resources hypothesized to exist because resources of that type have been found in the same general area and geological setting (gold “rush” mentality)

  • Speculative Resources – resources that are speculated to exist even though resources of that type haven’t been found in that area (see review figure)


  • Resources can also be classified as renewable and nonrenewable

  • Renewable resources are replaceable on a human time scale while nonrenewable resources are not

  • What is an example of a renewable and a nonrenewable resource?

Water as a resource1
Water as a Resource

  • Obviously no society can prosper without a reliable source of fresh water

  • Fresh, potable water has become a precious commodity in many parts of the world, here in the U.S. there are many legal battles raging, especially in the West, over water usage rights

Water as a resource2
Water as a Resource

  • Remember, the surface and subsurface waters of Earth are part of the hydrologic cycle (see figure)

  • We’ll initially focus on groundwaters since they constitute such a large percentage of our liquid freshwater resource (see figures)

Hydrologic cycle – powered by solar energy, the continual circulation of Earth’s water

through the atmospheric, surface, and subsurface reservoirs.

Groundwaters constitute circulation of Earth’s water

about 95% of Earth’s

liquid freshwater resources!

About half of the US population relies

on groundwater for drinking water!

Groundwater circulation of Earth’s water

  • The origin of groundwater is water that infiltrates the surface; however, not all subsurface water is termed groundwater

  • Groundwater is defined as subsurface water present in the saturated zone - here all the pore spaces between adjacent rock and sediment particles are saturated with water (see figure)

Groundwater circulation of Earth’s water

  • Groundwater moves due to the influence of gravity and the pressure from the weight of the overlying rock and sediment (squeezed sponge analogy)

  • Therefore, groundwater moves toward zones of lower pressure (i.e., the surface) (see slides)

Groundwater circulation of Earth’s water

  • As you’re seeing the groundwater and surface water systems (streams, lakes, wetlands) are typically intimately connected

  • Today, many scientists are advising that we consider these as one resource system

  • Why? Think of the practical and environmental applications when viewing the next slide.

Oakland Press circulation of Earth’s water

June 12, 2005

Brochure distributed in 2005 by the Brandon Township circulation of Earth’s water

Phase II Stormwater Management Education Group

Oakland circulation of Earth’s water

Press 7/26/07

Future concern
Future Concern? circulation of Earth’s water

Groundwater circulation of Earth’s water

  • Significant quantities of groundwater are found only in sediments or rocks that are sufficiently porous and permeable (How would you define these terms?)

  • Porosity – the percentage of void (open) space a substance contains

  • Permeability – a measure of how readily a substance transmits fluids

Groundwater circulation of Earth’s water

  • Aquifers - rock or sediment bodies that absorb and transmit water very effectively

  • Aquicludes - rock or sediment bodies that absorb and transmit water very poorly

  • Aquitards – rock or sediment bodies with properties between those of an aquifer and aquiclude

  • See the following table and try to discern the best aquifer material

Groundwater accumulation
Groundwater Accumulation circulation of Earth’s water

  • Sediments like sands and gravels (which typically underlie the surface soils in southeast MI to maximum depths of 400 ft) typically make good aquifers

  • ~97% of Oakland County wells terminate into sand/gravel aquifers

Groundwater accumulation1
Groundwater Accumulation circulation of Earth’s water

  • Rocks like limestone and poorly cemented sandstones typically make good aquifers

  • Clay sediments, sedimentary rocks like shale and nearly all igneous and metamorphic rocks are aquicludes except under rare circumstances (see slides)

fractures circulation of Earth’s water

e.g., granite

Groundwater circulation of Earth’s water

  • Deep (hundreds of feet) accumulations of groundwaters may have taken thousands of years to accumulate; significant volumes of groundwater are not typically found below about 2300 feet (see slide) Why?

Groundwater flow rates
Groundwater Flow Rates circulation of Earth’s water

  • Groundwater flow rates depend on two factors: 1) the permeability of the rock or sediment, and 2) the slope of the water table (tilt of the rock or sediment body to the ground surface)

  • Groundwater flow rates vary widely from a few inches a year in impermeable materials to perhaps 500 – 10000 ft/day in very porous and permeable materials (e.g., some gravels) (see figure)



Groundwater circulation of Earth’s water

  • On the average, groundwaters flow a few inches to about a foot per day; remember this is a gross average

Artesian springs
Artesian Springs circulation of Earth’s water

  • An artesian system requires a confined aquifer (an aquifer directly overlain and underlain by low-permeability rocks) to form and is defined as a system where the water rises under its own pressure (no pumping required) past the top of the aquifer (see slide)

Geologic work of groundwater
Geologic Work of Groundwater circulation of Earth’s water

  • Certain rocks (e.g., limestone) are prone to slow dissolution by slightly acidic groundwaters – what is the primary acid?

  • The dissolving of these rocks may lead to the formation of caverns/caves, sinkholes and other unique features often called “karst topography”(see slides)

Acidic soil water circulation of Earth’s water

Limestone or similarly soluble


Caverns exposed when water table


Geologic work of groundwater1
Geologic Work of Groundwater circulation of Earth’s water

  • Sinkholes – depressions formed by the collapse of the ground surface into an underlying void (cavern)

  • Sinkholes vary in size and are fairly common in areas underlain by cavernous limestone

  • Think about the potential hazards (obvious and nonapparent) of sinkholes as we view the following slides

Geologic work of groundwater2
Geologic Work of Groundwater circulation of Earth’s water

  • Karst topography – landscape, predominantly formed by the dissolution of soluble bedrock like limestone, that typically hosts sinkholes, sinking (disappearing) streams, and caverns/caves (see slide)

Consequences of groundwater withdrawal
Consequences of Groundwater Withdrawal karst topography!

  • If groundwater is removed faster than it is replenished the water table lowers, but not uniformly as one may think

  • Cone of depression – a cone-shaped drawdown in the water table immediately adjacent to a pumping well (see slide)

  • Possible consequences: negative impact on the water levels in nearby wells and ground subsidence (see slides)

Effect of land subsidence karst topography!

Geotimes, July 2008 karst topography!

Consequences of groundwater withdrawal1
Consequences of Groundwater Withdrawal karst topography!

  • Remember: in many major metropolitan and intensively farmed areas groundwater is essentially a nonrenewable resource and groundwater depletion is problematic (see slide)

  • What is meant by the term nonrenewable resource?

Shaded sections karst topography!

represent sections of the U.S.

where groundwater extraction

rates significantly exceed

recharge rates

Groundwater Depletion West of karst topography!

The Mississippi

Consequences of groundwater withdrawal2
Consequences of Groundwater Withdrawal karst topography!

Along marine coastlines or on oceanic islands, excessive withdrawal of groundwaters can facilitate a form of groundwater pollution called “saltwater intrusion” (see figure)

Other consequences of urbanization
Other Consequences of Urbanization karst topography!

  • Urbanization can result in a loss of groundwater recharge area if significant portions of ground overlying the aquifer are covered by impermeable materials (e.g., asphalt) or buildings (see figure); draining and infilling wetlands also reduces recharge

Other consequences of urbanization1
Other Consequences of Urbanization karst topography!

  • Artificial recharge can help reduce this problem (see figure)

  • Potential problems?

Water supply and use topics

Water Supply and Use Topics karst topography!

Water supply and use
Water Supply and Use karst topography!

  • Although a seemingly tremendous volume of precipitation falls on average upon the surface of the contiguous U.S. daily (see slide), the precipitation and subsequent outcomes are not uniform (see slide)

  • Therefore water supplies in the contiguous U.S. vary in volume and quality

Numbers represent karst topography!

billions of gallons

per day

Water supply and use1
Water Supply and Use karst topography!

  • Note the difference between “water withdrawals” (water withdrawn from a source) and “conveyance loss” and “consumption” (consumptive use – water not returned to the source) (see slides)

Water supply and use2
Water Supply and Use karst topography!

  • The increased demand for water accompanying population growth and expanded development has led to bitter legal battles and disputes, within and between nations, over water access rights (see slides)

Water supply and use3
Water Supply and Use karst topography!

Egypt pushes Ethiopia to scrap Nile dam karst topography!

Published: Oct. 19, 2012 at 10:50 AM

CAIRO, Oct. 19 (UPI) -- Egypt increasingly views Ethiopia's plan to build a massive 6,000-megawatt hydroelectric dam on the Nile River as a threat to its national security because it will seriously cut the Arab state's water supplies.Egypt depends on the Nile for virtually all of its water and is mounting a major diplomatic and economic campaign to scupper the plan. "Even direct military action by Egypt cannot be ruled out," observed the U.S. global security consultancy Stratfor.Both countries have undergone major political upheavals recently, which have added to the tension in a long-running battle for control of the world's longest river which rises in the Ethiopian highlands. Egypt's Muslim Brotherhood now controls the presidency and Parliament following the February 2001 downfall of longtime dictator Hosni Mubarak and is locked in a struggle for supremacy with the military.Longtime Ethiopian ruler, Prime Minister Meles Zenawi, as harsh a dictator as Mubarak and whose ethnic Tigray group has long dominated the military, died Aug. 20, leaving a leadership vacuum and internal rivalries.

What’s the Great karst topography!

Lakes Compact?

Great lakes compact
Great Lakes Compact karst topography!

  • As stated in the adjacent article the U.S. Congress and president must still approve this legislation

  • Source: Oakland Press, 7/10/08

  • This legislation was subsequently approved by the Congress and president

Water supply and use4
Water Supply and Use karst topography!

  • Adequate supplies of clean water will be one of the most significant challenges worldwide in the 21st century

  • See figure; 1700 cubic meters per person per year of fresh water is considered adequate

Water supply and use5
Water Supply and Use karst topography!

  • Depending on the situation, one or more measures may be undertaken to extend water supplies; the three primary water supply extension measures include:

  • Conservation

  • Interbasin Water Transfer

  • Desalination

Water supply extension measures
Water Supply Extension Measures karst topography!

  • Conservation – as population increases, significant reduction in water withdrawals won’t occur due to conscious deprivation but by advances in technology which produce the same outcome with less water

  • Examples?

Examples of? karst topography!

Water supply extension measures1
Water Supply Extension Measures karst topography!

  • Interbasin Water Transfer – movement of water from one drainage basin to another (e.g., via aqueducts or pipelines)

  • Is this a relatively new idea?

  • Potential implications for the Great Lakes region? (Don’t forget about the Great Lakes Compact)

Water supply extension measures2
Water Supply Extension Measures karst topography!

Desalination – conversion of saline to fresh water via filtration or distillation (see figure)

Potential disadvantages?

Final thought
Final Thought karst topography!

  • Relatively new idea: what’s your (our) “virtual” water use? (The total amount of water used to create a product.)

  • Example: most studies suggest a pound of beef requires, minimally, nearly 15- 20 times more water to produce than a pound of grain

  • See following table and figure

Virtual water use
Virtual Water Use karst topography!

Source: National Geographic, April 2010

Water quality measures
Water Quality Measures karst topography!

  • Concentrations of water contents are routinely measured in parts per million (ppm) and parts per billion (ppb)

  • 1ppm = 1 milligram (mg) of a dissolved substance per liter (L) of solution; 1 ppm = 1 mg/L

  • 1 ppm = 1000 ppb; 1 ppb = 0.001 mg/L

  • Some substances can now be measured in concentrations as low as 1 part per trillion!

General water quality measures
General Water Quality Measures karst topography!

  • Total Dissolved Solids (TDS) – the total amount of dissolved solids in solution; most public water supplies can’t legally distribute water with a TDS value > 500 ppm

  • Be careful: a TDS value < 500 ppm doesn’t ensure potable/healthy water

General water quality measures1
General Water Quality Measures karst topography!

  • Water hardness – a measure of the total amount of calcium and magnesium dissolved in a water source

  • Hard water – water whose dissolved calcium and magnesium levels exceed 100 ppm

  • Why do people usually soften hard household waters and what are the health risks of softened water to specific populations?

Assessments of analytical measures
Assessments of Analytical Measures karst topography!

  • Chemical analysis can be qualitative or quantitative in nature

  • Qualitative analysis – chemical analysis that determines the presence of a substance above a certain detection threshold (e.g., dissolved arsenic in drinking water above 2 ppb)

  • Quantitative analysis – chemical analysis that seeks to accurately measure the amount of a substance

Assessments of analytical measures1
Assessments of Analytical Measures karst topography!

  • Analytical precision – a measure of the reproducibility of results – Do you obtain the same, or nearly the same, results on repeat analyses of samples of the tested material?

  • Analytical accuracy – a measure of how close the measured value is to the true value

  • Do not use the terms “analytical precision” and “analytical accuracy” interchangeably!

Water testing laboratory
Water Testing Laboratory karst topography!

  • Conduct all analyses first; review data and answer questions at home if necessary – lab data sheets are due at the beginning of next class

  • Tips: pH and phosphate are two different tests! For the pH test, follow instructions (C) for testing waters of unknown pH

  • Phosphate test: follow instructions for low range

  • Hardness test : follow directions for total hardness

  • Dissolved oxygen: follow directions on inside cap cover of test kit; begin with sample collection and preservation