Water Resource Management, Groundwater Basics Integrated Water Resource Management Groundwater basics
Water Resource Management, Groundwater Basics
Integrated Water Resource Management
Groundwater basics
Water Resource Management, Groundwater Basics
How wet is our planet?� 70% of the earth’s surface
is covered in water.• The majority of this water is
contained in the oceans as salt water.
• Other sources for water include the polar ice caps, the atmosphere, and groundwater.
Water Resource Management, Groundwater Basics
How wet is our planet?
� Surprisingly, less than 1% of the earth’s total supply of water is readily suitable for drinking.
� Of this supply of drinking water, 98% of it is found in underground aquifers. • This water source
is called groundwater.
Water Resource Management, Groundwater Basics
What is groundwater?� Groundwater is water that is
found underground in the cracks and spaces in soil, sand, and rocks.
� Groundwater is stored in—and moves slowly through—geologic formations called aquifers.
Water Resource Management, Groundwater Basics
Why is groundwater important?
� Groundwater is a source of drinking water for more than 50% of the people in the U.S.
� Agricultural irrigation is the largestuser of groundwater.
� Paper manufacturing, food processing, and other industrial processes also use a large amount of groundwater.
Water Resource Management, Groundwater Basics
Where is groundwater found?
� Groundwater is available, at least in small amounts, nearly everywhere, though the quantity available varies from one region to another based on geologic materials and other conditions.
� Humans access groundwater with the use of a pump driven water well or windmill.
Water Resource Management, Groundwater Basics
How does groundwater move?
� Underground, water slowly moves from an aquifer’s recharge areas (areas where water seeps into the aquifer from rain fall, snow melt, etc.) to it’s discharge area (like streams, springs and lakes).
� Groundwater is always moving (this is called groundwater flow) and moves very slowly--only inches per year.
groundwater flow discharge area
evaporation
recharge area
precipitation
condensation
runoff
transpiration
aquifer
water table
infiltration
Hydrologic Cycle
Water Resource Management, Groundwater Basics
Most available freshwater is groundwater
Oceans97.2%
Atmosphere0.0001%
0.61%(97%)
Streams and Lakes
0.01%(3%)
The Hydrologic Cycle, Quantities
Water Resource Management, Groundwater Basics
Hydrologic Cycle, Definitions
Fiction: Groundwater is often thought of as an underground river or lake. Only in caves or within lava flows does groundwater occur this way. Instead, groundwater is usually held in porous soil or rock materials, much the same way water is held in a sponge.
Water Resource Management, Groundwater Basics
Hydrologic Cycle, Unsaturated Zone
Water moves through the unsaturated zone into the saturated zone, where all the interconnected openings between rock particles are filled with water. It is within this saturated zone that the term "groundwater" is correctly applied. Groundwater is held in aquifers.
Water Resource Management, Groundwater Basics
Groundwater Aquifers
Aquifer is the term given to a rock unit that will yield water in usable quantities to wells or springs. An aquifer can be visualized as a giant underground sponge which holds water and which, under certain conditions, will allow water to move through it.
Water Resource Management, Groundwater Basics
• Volcanic Processes:– Groundwater controls water
content of magmas– Groundwater injected by
magmas can metamorphose country rocks
– Geysers are an example of volcanic activity interacting with groundwater
Groundwater and volcanoes
Water Resource Management, Groundwater Basics
Groundwater Movement• It is a common misconception that groundwater is found in
underground rivers, like those that form limestone caverns. In fact, groundwater is more like the water in a sponge, held within the tiny pores of the surrounding aquifer material. Much like the flow of water in a river, however, the flow of groundwater is subject to gravity and is almost always in motion, flowing from areas of higher elevation to areas of lower elevation.
• It is important to note that the rate of groundwater flow, especially in confined systems, is very slow compared to the flow of water on the surface. It is typically in the range of several inches per year to several feet per year.
• For water to move freely through a rock, the pores and/or fractures must be large enough and connected enough so that the friction from the water moving past the rock particle does not impede the flow. The degree of an aquifer's porosity and conductivity is key to the movement of groundwater through an aquifer.
Water Resource Management, Groundwater Basics
– Permeable pathways are controlled by distributions of geological materials
– Where groundwater is available as a resource is controlled by geology
– Contaminant transport in the subsurface is controlled by geology
Geology controls groundwater flow
Groundwater movement, large scale
Water Resource Management, Groundwater Basics
Groundwater movement, small scale
Ground water can move through pores or fractures
Water Resource Management, Groundwater Basics
Groundwater and WellsWhen pumping begins, water begins
to flow towards the well, in contrast to the natural direction of ground water movement. In response, the water level in the well falls below the water table in the surrounding aquifer. As a result, water begins to move from the aquifer into the well.
As pumping continues, the water level in the well continues to decrease until the rate of flow into the well equals the rate of withdrawal from pumping. The movement of water from an aquifer into a well results in the formation of a cone of depression
Water Resource Management, Groundwater Basics
Typical Groundwater Problem: Well Near a River
Only clean groundwater is pumped out
Both clean groundwater and possibly contaminated river water is pumped out
Water Resource Management, Groundwater Basics
What causes groundwater
contamination?
� Leaky underground storage tanks
� Poorly constructed landfills and septic systems
� Improperly abandoned mines and wells
� The overuse of fertilizers, pesticides, and road salts
� Runoff from livestock confinement areas
� Careless industrial and manufacturing organizations
Water Resource Management, Groundwater Basics
What are the effects of groundwater contamination?
� Groundwater contaminated with bacteria, chemicals, pesticides, gasoline or oil can result in serious human health problems.
� Although it is possible to clean up groundwater contamination, it may cost communities several millions of dollarsand can double or triple the cost of water.
� It costs far less to prevent contamination than attempt to clean it up.
Water Resource Management, Groundwater Basics
How can groundwater contamination be prevented?
� Development of wellhead protection areas.� Public information and education on
groundwater.� Proper use, storage, and disposal of
chemicals.� Monitoring activities.� Land use planning and
implementation programs.
Water Resource Management, Groundwater Basics
Too Much Discharge?
In some areas overwithdrawal can make the ground sink because ground water pressure helps to support the weight of the land. This is called subsidence.
Water Resource Management, Groundwater Basics
Role of groundwater in Great Lakes (GL)
• Provides recharge to aquifers• Discharges to lakes, tributaries and other surface water
bodies– Direct discharge rates to GL estimated 800-6,700
ft3/sec– Indirect discharge accounts for 25-97% of streamflow
• Transports pollutants• Provides withdrawals for drinking water, agriculture,
livestock, mining, hydroelectric and thermoelectric power generation
Water Resource Management, Groundwater Basics
Quantity
• Great Lakes Basin contains 1,000 mi3 of ground water (~ 20% of the total water volume of lakes)
• Ground water is the source of drinking water for more than 8 million people in the Basin
• Ground water is estimated to contribute 22-42% of the inflow to the net water supply in the Great Lakes
• Millions of dollars have been spent regulating lake levels by the International Joint Commission (IJC) and US Army Corps of Engineers using models that do not directly account for ground water…
Water Resource Management, Groundwater Basics
Source: USGS, “Indirect Ground-Water Discharge to the Great Lakes”
Water Resource Management, Groundwater Basics
Hydrogeology
• Two types of aquifer systems in GLB– Surficial system
• Most widespread in Basin• Composed of high yield glacial deposits• Greatest hydraulic connection with surface waters• Recharges underlying bedrock aquifers
– Bedrock systems• Vary throughout the Basin, USGS documented 10 different aquifers• Some confined, some semi-confined, and some unconfined• Yields vary depending on aquifer, but most industrial withdrawals
come from these systems• Most are recharged by overlying Surficial aquifers or directly from
surface waters at outcrops
Water Resource Management, Groundwater Basics
Surficial Aquifer System
Source: USGS National Ground Water Atlas
Water Resource Management, Groundwater Basics
Key Management Questions
• How does ground water influence lake levels?• How do lake levels affect groundwater?
– Regulation – Climate change
• At what point do withdrawals of ground water resources begin to have significant adverse affects in the basin? – Reduced inflow to Lakes– Water quality in wetlands– Locations of watershed boundaries (groundwater divides)
Water Resource Management, Groundwater Basics
Models as management tools• Surface water routing models are currently used by
USACE (United States Army Corps of Engineers) to manage lake levels
• Groundwater models are used extensively for localized analysis but not over entire GL system
• Constructing a model over entire GL system requires decisions regarding:– Level of geographic and hydrologic detail– Data acquisition and management– Numerical and computational approach– Manner of describing surface/groundwater
interactions
Water Resource Management, Groundwater Basics
Example: Ohio1843: Acton v. Blundell
“English Rule”
The landowner can pump groundwater at any rate even if an adjoining property owner were harmed.
1861: Frazier v. BrownEnglish Rule in Ohio
Groundwater is “…occult and concealed…” and legislation of its use is “…practically impossible.”
1984: Cline v. American AggregatesEnglish Rule overturned in Ohio
Justice Holmes: “Scientific knowledge in the field of hydrology has advanced in the past decade…” so it “…can establish the cause and effect relationship of the tapping of underground water to the existing water level.”
Water Resource Management, Groundwater Basics
Example: Wisconsin
1903: Huber v. MerkelEnglish Rule in Wisconsin
A property owner can pump unlimited amounts of groundwater, even with malicious harm to a neighbor.
1974: Wisconsin v. Michels Pipeline Constructors Inc.English Rule Overturned
Landowners no longer have “an absolute right to use with impunity all water that can be pumped from the subsoil underneath.”
Water Resource Management, Groundwater Basics
• Water-level changes in the Texas--Oklahoma-High Plains area.
• The Ogallala aquifer --composed of water-bearing sands and gravel that underlie about 400,000 km2.
• Water is being used for irrigation at a rate up to 20 times more than natural recharge by infiltration.
• Water level (water table) in many parts has declined and the resource eventually may be used up.
Ogallala Aquifer
S. Hughes, 2003