Groundwater Occurrence & Movement:Groundwater Occurrence & Movement:An Introductory Discussion with Application to An Introductory Discussion with Application to

Northeastern IllinoisNortheastern Illinois

H. Allen Wehrmann, P.E., DirectorCenter for Groundwater Science

Illinois State Water Survey

April 24, 2007

AcknowledgmentsAcknowledgments

Martin Jaffe, University of Illinois, ChicagoMartin Jaffe, University of Illinois, ChicagoScott Meyer, Center for GW Science, ISWSScott Meyer, Center for GW Science, ISWSSteve Burch, Center for GW Science, ISWSSteve Burch, Center for GW Science, ISWSIL State Geological SurveyIL State Geological SurveyKane County Water Resources DepartmentKane County Water Resources Department

Topical Presentation OutlineTopical Presentation OutlineBasic Concepts and DefinitionsBasic Concepts and Definitions

The Hydrologic CycleThe Hydrologic CycleWhat is groundwater?What is groundwater?

Concepts & DefinitionsConcepts & DefinitionsPorous Flow vs. Fractured FlowPorous Flow vs. Fractured FlowAquifers vs. Aquifers vs. AquitardsAquitardsArtesian vs. Water Table ConditionsArtesian vs. Water Table Conditions

Regional Groundwater Flow SystemsRegional Groundwater Flow SystemsWell & Aquifer HydraulicsWell & Aquifer HydraulicsGroundwater ModelingGroundwater Modeling

The Hydrologic CycleClimate, surface water, and groundwater are linked

Porous SystemsPorous Systems

Groundwater flows throughpore spaces between grains

Porosity & Effective Porosity RangesPorosity & Effective Porosity Ranges

0.5 0.5 –– 10105 5 -- 1515SandstoneSandstone

0.5 0.5 –– 551 1 -- 1010ShaleShale

0.1 0.1 –– 555 5 -- 1515Limestone/dolomiteLimestone/dolomite

10 10 -- 555524 24 –– 5555Sand/GravelSand/Gravel

0.1 0.1 –– 101034 34 -- 6060ClayClay

0.1 0.1 –– 101034 34 -- 6161SiltSilt

EffEff. Porosity . Porosity (%)(%)

Porosity Porosity (%)(%)MaterialMaterial

Fractured SystemsFractured Systems

FracturedLimestone

or Dolomite

Aquifers vs. Aquifers vs. AquitardsAquitards

An aquifer is a saturated bed, formation, or group of formations which yields water in sufficient quantityto be of consequence as a source of supply.

An aquitard yields inappreciable quantities of water to wells compared to an aquifer but through whichleakage of water is possible. Aquitards often act as confining beds.

Unconfined vs. Confined GroundwaterUnconfined vs. Confined Groundwater

An unconfined aquifer is one in which groundwaterpossesses a free surface open to the atmosphere.The upper surface of the zone of saturation is calledthe water table.

A confined aquifer is one in which groundwater isconfined under pressure by overlying and underlyingaquitards or aquicludes and water levels in wells riseabove the top of the aquifer. Also called an artesianaquifer.

Land Surface

UnconfinedAquifer

Water Table

Bedrock

Unsaturated (Vadose) Zone

Saturated Zone

Unconfined Aquifers

Land Surface

Unconfined Aquifer

Water Table

Bedrock

Unsaturated (Vadose) Zone

Saturated Zone

Confined Aquifer

Confining Layer - AquitardPotentiometric Surface

Confined Aquifers

Confined Aquifers & Artesian WellsConfined Aquifers & Artesian Wells

Land surface

Aquifer

Water table

Flowing artesian well

Regional Groundwater Flow SystemsRegional Groundwater Flow Systems

200’

100’

20 miles

10’

0.1 mile

20’

Depth0’

Groundwater – Stream Interaction

Regional Flow Systems

Groundwater – Stream Interaction

Regional Flow Systems

Groundwater – Stream Interaction

Regional Flow Systems

Groundwater – Stream Interaction

Regional Flow Systems

Groundwater Flow VelocitiesGroundwater Flow Velocities

10 10 –– 10001000’’s feet per s feet per dayday

Highly fractured Highly fractured limestonelimestone

< 0.5 feet per day< 0.5 feet per daySandstoneSandstone

< 0.1 feet per day< 0.1 feet per dayClayClay

0.1 0.1 –– 0.5 feet per 0.5 feet per daydayClayey sandClayey sand

1 1 –– 5 feet per day5 feet per dayClean sandClean sand

55--10 feet per day10 feet per dayGravelGravel

VelocityVelocityMaterialMaterial

IL GeologyIL Geology––glacial glacial

materialsmaterials

Glacial depositional processesGlacial depositional processes

Regional Bedrock TopographyRegional Bedrock Topography

Green= higher elevations; Light violet= lower elevations

Major Sand &Gravel Aquifers

Withdrawals from Sand and Gravel Aquifers

Total use ~ 350 mgd+ ~200 mgd for irrigation

Aquifers of Northeastern IllinoisAquifers of Northeastern Illinois

Unconsolidated Aquifer System

Shallow Bedrock Aquifer

Deep Bedrock Aquifer System

Elmhurst-Mt. Simon Aquifer

ChicagoDeKalbWest East

Cross-Section Modified from Bretz (1939)

Major ShallowBedrock Aquifers

Withdrawals fromShallow Bedrock Aquifers

Total use > 200 mgd

Major Deep Bedrock Aquifers

Withdrawals from Deep Bedrock Aquifers

Total use ~ 100 mgd

Cone of DepressionCone of Depression

Well/Aquifer Interactions

Overlapping Cones of DepressionOverlapping Cones of Depression

Well/Aquifer Interactions

Well/Aquifer Interactions

Overlapping Cones of Depression – Well Interference

Well/Aquifer Interactions

BA

Overlapping Cones of Depression – Well Interference

Well/Aquifer Interactions

Overlapping Cones of Depression – Well Interference

BA

Well/Aquifer Interactions

Overlapping Cones of Depression – Well Interference

BA

Well/Aquifer Interactions

Overlapping Cones of Depression – Well Interference

BA

NE Illinois Deep Bedrock Withdrawals, NE Illinois Deep Bedrock Withdrawals, 19001900--20002000

1860 1880 1900 1920 1940 1960 1980 2000Year

0

20

40

60

80

100

120

140

160

180

200

Mill

ion

Gal

lons

per

Day

182.9 mgd(1979)

71.9 mgd(2000)

Estimated Practical Sustained Yield (Ideal Well Distribution)= 65

mgd

Estimated Practical

Sustained Yield (1958

Well Distribution)=

46 mgd

DistributionOf DeepBedrockAquiferPumpage

Source: Jaffe

PotentiometricPotentiometricSurface of theSurface of theDeep Bedrock Deep Bedrock

Aquifer System, Aquifer System, Fall 2000Fall 2000

Potentiometric Surface Across NE Illinois

WESTEAST

DeKalb Elburn

Geneva ElmhurstBellwood

Industr ial site in Chi cago

-1200

-1000

-800

-600

-400

-200

0

200

400

600

800

1000

-1000

-800

-600

-400

-200

0

200

400

600

800

1000

-1200

Elevation (ft) Elevation (ft)

Ironton-Galesville Ss

St. Peter Ss

Deep Well Water Levels, Cook CountyDeep Well Water Levels, Cook County

Oswego #3 (Kendall County)Oswego #3 (Kendall County)

1950 1960 1970 1980 1990 20000

100

200

300

400

500

600

Ele

vatio

n ab

ove

Sea

Lev

el (f

eet)

Groundwater Flow Groundwater Flow Modeling: NE IllinoisModeling: NE IllinoisRegional Model GridRegional Model Grid

226 rows226 rows174 columns174 columns18 layers18 layers707,832 nodes707,832 nodesMinimum grid Minimum grid spacing of 2500spacing of 2500’’Maximum grid Maximum grid spacing of 80,000spacing of 80,000’’

Modeled Heads in upper GalenaModeled Heads in upper Galena--Platteville Platteville -- 20022002

Modeled Heads in lower GalenaModeled Heads in lower Galena--Platteville Platteville -- 20022002

Modeled Heads in Modeled Heads in AncellAncell (St. Peter) (St. Peter) -- 20022002

Modeled Heads in IrontonModeled Heads in Ironton--Galesville Galesville -- 20022002

Look for more information and updates:http://www.sws.uiuc.edu/wsp

E-mail me with questions:alex@uiuc.edu

Thanks!