groundwater. freshwater glaciers atmosphere groundwater lakes soils rivers wetlands 3% of total...
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Groundwater
Freshwater
GlaciersAtmosphereGroundwaterLakesSoilsRiversWetlands
3% of totalEarth water
Aquifers/Groundwater
0.6% of total earth water.
98% of all readily available freshwater
Supplies ½ of the drinking water in U.S.and 90% of the drinking water in FL.
Aquifers
Water-bearing formation thatcan store and release usableamounts of water.
Aqua – waterFerre – to carry
Where is Groundwater?
Water found in pore spaces, seamscracks, and fractures in geologic material or soils beneath the surface of the earth
SandsSilts
GravelsMudsClaysRock
Water-bearingUnit materials
Aquifers and Aquifer Types
Consolidated
Unconsolidated
Confined
Unconfined
Aquifer Classification
Basic Aquifer Classification
Unconsolidated or Consolidated
Consolidated: sandstone, limestone, granite
Unconsolidated: granular sand, gravel, clays, silts
Water held in pore spaces between grainsof sand, gravel, clays, or rock fragments
Water held in cracks, fissures and seamsin solid rock formations.
Unconsolidated Aquifers
Unconsolidated sands and gravel
Water-Bearing Unit
Unconsolidated: sand and gravel
saturated thickness ranges from a few feet to more than 1000 feet
thick
thin
174,000 mi²
High Plains Aquifer
27 percent of the irrigated land in the United States overlies this aquifer yields about 30 percent of the nation's ground water used for irrigation
20% of U.S. grain production
provides drinking water to 82 percent of the people who live within the aquifer boundary
Semi-arid Region
Consolidated Aquifers
Consolidated Rock: igneous or sedimentary
Water-Bearing Unit
Rocks formed from the cooling and solidification of molten magma originating in the earth's core
Igneous Rocks
Extrusive rock is formed when the solidification process occurs at or near the ground surface. These rocks are generally very permeable because of the "bubbling" of gases escaping during cooling and solidification.
horizontal fracturing
The Columbia River Plateau covering eastern Washington and Oregon, and Idaho, averages about 500 m in thickness and is one of the largest basalt deposits in the world. Basalt aquifers are critically important water sources for the HawaiianIslands.
Consolidated Aquifers
Granite
Consolidated Rock Aquifers
Sandstone and Carbonate
Sandstone is a cemented form of sand and gravel
St. Peter Sandstone in northeastern Illinois covers more than 290,000 mi2 and averages 80 to 160 ft in thickness
Carbonate formations include limestone (CaCO3) and dolomite
Exhibit mostly secondary porosity due to fracturing and dissolution openings
Sedimentary
Consolidated Aquifers: Guaraní Aquifer
Sedimented sandstones deposited during the Triassic and Jurassic periods
overlaid with igneous basalt with low-permeability
Thickness: 50 m to 800 m
Slowly Recharged
37,000 km³ of water
fresh drinking water for 200 years
(166 km³/year)
Argentina, Brazil, Paraguay and Uruguay
5% of world population
Confined and Unconfined Aquifers
Low PermeabilityGeologic or Soil material
Water
HighPermeability
Unconfined Aquifer
Saturated Zone
Groundwater table
Saturated Zone thickness dependent on rainfall
Open to the surface, butconfined at greater depthby low-permeability material
Low permeability – slow water
Unconfined or Surficial Aquifer
Confined Aquifers
A generally inclined, water-bearing formation located between impermeable layers
of clay, rock, or shale.
Confining units (aquicludes)
Water-bearing unit (consolidated or unconsolidated)
Water-bearing unit is confined between two layers of material that are not permeable to water (confining units).
Confined Aquifers
Water-bearing unit
Impermeable material
Recharge
Flow
High Pressure
Confined and Unconfined
impermeable
impermeable
Recharge
Water-bearing unit
Water-bearing unit
Recharge
Unconfined aquifer (surficial aquifer)
Open to the surface, but confined at greater depth by low-permeability material
Recharge is generally by rainfall and surface water bodies
Confined aquifer
Water-bearing unit is confined between two layers of material that are not permeable to water (confining units).
Recharge is in areas where the upper confining unit is thin or absent
Water-bearing units: sands, gravel, silts, clays, porous or fractured rock
Recharge, Usage, and Water Mining
Aquifer Recharge: precipitation
surface water runoffLakes
StreamsRivers
WetlandsSinkholes
Non-Renewable Groundwater Resources
Groundwater resources are never strictly non-renewable.
In cases where present-day aquifer replenishment is very limited but aquifer storage is very large, the groundwater resource can be termed non-renewable
Non-Renewable Groundwater Resources
Time for Replenishment
Climate Changes
Non-renewable aquifers are often described as “fossil” aquifers.
These are aquifers with no appreciable modern recharge.
“Fossil” Aquifers
Most often found in arid climates, fossil and other non-renewableAquifers are an important water resource for many nations.
Nubian Sandstone aquifer underlying Chad, Egypt Libya and Sudan.
Qa-Disi aquifer between Jordan and Saudi Arabia
Great Artesian Basin of Australia
Groundwater is isolated from modern recharge
Contemporary climate does not support sufficient recharge
formed between 100 and 250 million years ago
Formed 145.5 to 65.5 million years ago
Average rainfall < 5 mm/year Closed water system•Age of most water > 20,000 years,
Settings associated with non-renewable groundwater
hyper-arid area with average rainfall of less than 4 in/yr and prolonged dry periods–bulk of aquifer contains fossil groundwater, which infiltrated during humid period s at least 10,000 years or more ago and still has an active residual flow to a perennial discharge area.
temperate humid region with annual rainfall in excess of 1,000 mm/yr normally generating renewable groundwater resources, but highly-confined portion of aquifer system contains essentially non-renewable groundwater as a result of geological structure and geomorphological history – and this is potentially of local strategic importance.
No recharge
Non-renewable aquifers are oftenAssociated with Water Mining
Withdrawals exceed recharge creating deficits in the aquifer
The world water deficit is concentrated in China, the Indiansubcontinent, the Middle East, North Africa, and North America
Extensive exploitation of renewable and non-renewable aquifers
China
India
Iran
Israel
Jordan
Mexico
Morocco
Pakistan
Saudi Arabia
South Korea
Spain
Syria
Tunisia
United States
Yemen
Countries currentlyWithdrawing more Groundwater than Is replenished.
GROUNDWATER (Mm3/a)
COUNTRY Share of demand * Total use Non-renewable
Algeria 54% 2,600 1,680
Saudi Arabia 85% 21,000 17,800
Bahrain 63% 258 90
Egypt 7% 4,850 900
UAE 70% 900 1,570
Jordan 39% 486 170
Libya 95% 4,280 3,014
Oman 89% 1,644 240
Qatar 53% 185 150
Tunisia 59% 1,670 460
Yemen 62% 2,200 700
*percentage of total use provided by groundwater
Saudi Arabia and Libya, use 77% of the estimated total world extraction of non-renewable groundwater for urban supply and irrigated agriculture.
The Middle East
End Lecture 16
Sea Levels
Temporary reestablishment of carbonate deposition
Vulnerability
One gallon of gasoline cancontaminate 1 million gallonsof drinking water
1 ppm
MetalsNutrientsPesticidesPetroleum Solvents