Homework III

Emerging Water Contaminants

Posted on Website this afternoon

Due April 18 All answers must be typed

Groundwater and Soil Water

Freshwater

GlaciersAtmosphereLakesRiversSoilsGroundwater

3% of totalEarth water

Aquifers

Water-bearing formation thatcan store and release usableamounts of water.

Aqua – waterFerre – to carry

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.

What is Groundwater?

Water found in pore spaces in geologic material or soils beneath the surface of the earth

SandsSilts

GravelsClaysRock

Materials

Depth to groundwater is highly variable

Ultimate Source: precipitation

Replenished by surface water runoffLakesStreamsRiversWetlandsSinkholes

Aquifers and Aquifer Types

Consolidated

Unconsolidated

Confined

Unconfined

Aquifers

Basic Aquifer Classification

Unconsolidated or Consolidated

Consolidated: sandstone, limestone, granite

Can be low-yield or high-yield

Granite, sandstone Limestone, sand/gravel

Unconsolidated: granular sand or gravel

Consolidated Aquifer

Unconsolidated Aquifer

Unconsolidated: sand and gravel

Ogallala

saturated thickness ranges from a few feet to more than 525 feet

thick

thin

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

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

Consolidated aquifer: basalt, limestone, granite

Snake River AquiferBasalt consolidated aquifer

Rathdrum aquifer in northern Idaho

is an unconsolidated aquifer.

Basalt

Confined and Unconfined Aquifers

Aquitard/Aquiclude

Hydraulic conductivity: the ease with which water moves through material

Low ConductivityGeologic or Soil material

Water

HighPermeability(conductivity)

Unconfined Aquifer

Restrictive Zone

Saturated Zone

Capillary Fringe (unsaturated or Vadose zone)

Groundwater table

Unconfined Aquifer

Confined Aquifers

Confined Aquifer

A generally inclined, water-bearing formation located below an impermeable layer

of clay, rock, or shale.

High pressure

Confined Aquifers

Permeable materialImpermeable material

Confined and Unconfined

impermeable

impermeable

Florida’s Permeable Material: limestone

Florida’s Impermeable Material: Miocene Clays

Surficial aquifer

Confined Aquifer

Confining unit

Confining unit

Florida

Examples of World Aquifers

Shallow, Unconsolidated

North China Plain

½ China’s wheat, 1/3 corn

Levels dropping 3 ft/year

Shift to Deep fossil aquifer (non-replenishable)

Agricultural well depths can exceed 1000 feet ($)

Municipal well depths can exceed 3000 feet

Shallow aquifer largely depleted (replenishable)

China’s grain production has fallen from its historical peak of 392 million tons in 1998 to an estimated 358 million tons in 2005

China largely covered the drop-off in production by drawing down its once vast stocks until 2004, at which point it imported 7 million tons of grain.

99,900 wells were abandoned

India

21 million wells

water table is falling by 6 meters (20 feet) per year

falling water tables have dried up 95 percent of the wells owned by small farmers

drilling 1000m to reach water

agriculture is rain-fed and drinking water is trucked in

Population

Pakistan is growing by 3 million per year,

In the Punjab plain, the drop in water tables appears to be similar to that in India. In the province of Baluchistan, water tables are falling by 3.5 meters per year. within 15 years Quetta will run out of water if the current consumption rate continues

PakistanQuetta

Cenomanian-Turonian Mountain Aquifer

recharged from the West Bank

highly permeable

Coastal Aquifer

Width between 3 and 20 km

chief resource of water for Gaza

depth to groundwater 60 m to 8 m

Israel

80-100 sites lack infrastructure and mitigation measures

1984 Saudi national survey reported fossil water reserves at 462 billion tons

½ has been depleted

irrigated agriculture could last for another decade

al-Disi aquifer

sandstone aquifer not subject to recharge

Saudi Arabia

Partly in Jordan

The Sahara: Libya

1953

“fossil” water

Nubian Sandstone Aquifer

world's largest fossil-water reserve

located near the center of the world's largest continuous stretch of desert

two million square kilometers

equivalent to the flow of 200 years of water in the Nile River

The Great Man-made River Project

the largest underground network of pipes in the world

1300 wells more than 500 m deep

6,500,000 m³ water/day

Tripoli, Benghazi, Sirt

4 major basins

20,000km³

10,000km³

4,800km³

The Great Man-Made River Project

Water is 1/10 costOf desalinization

Next: Florida’s Aquifers

Vulnerability

One gallon of gasoline cancontaminate 1 million gallonsof drinking water

1 ppm

MetalsNutrientsPesticidesPetroleum Solvents