+ All Categories
Home > Documents > Aquifers 101

Aquifers 101

Date post: 22-Mar-2016
Category:
Upload: blade
View: 105 times
Download: 1 times
Share this document with a friend
Description:
Aquifers 101. Robert E. Mace Texas Water Development Board Groundwater 101 November 10, 2010. Outline. Yay for aquifers! Definitions Flow through an aquifer Pumping an aquifer. Outline. Yay for aquifers! Definitions Flow through an aquifer Pumping an aquifer. World Water Balance. - PowerPoint PPT Presentation
Popular Tags:
56
Transcript
Page 1: Aquifers 101
Page 2: Aquifers 101

Aquifers 101

Robert E. MaceTexas Water Development Board

Groundwater 101November 10, 2010

Page 3: Aquifers 101

Outline

• Yay for aquifers!• Definitions• Flow through an aquifer• Pumping an aquifer

Page 4: Aquifers 101

World Water Balance

From Freeze and Cherry (1979)

Page 5: Aquifers 101

groundwater and Texas

• ~60 percent of the 16.6 million acre-feet of water used

• ~80 percent of groundwater is used for irrigation

• groundwater provides 39 percent of water to cities

• tastes good when yer thirsty

Page 6: Aquifers 101

Examples of Aquifers

• The following slides are examples of aquifers

• As we discuss them, try to think of how you would define AQUIFER

Page 7: Aquifers 101

catfish farm wellEdwards aquifer

• flowing well at 40,000 gpm• 1/4 of San Antonio’s use• 9% of Annual Recharge• world’s largest artesian well

National Geographic (1993)

Page 8: Aquifers 101

Major aquifers

Page 9: Aquifers 101

Minor aquifers

Page 10: Aquifers 101
Page 11: Aquifers 101

Hickory Aquifer, sandstone

Page 12: Aquifers 101

Edwards-Trinity (Plateau) Aquifer, limestone

Page 13: Aquifers 101

Ogallala Aquifer, sand and gravel

Page 14: Aquifers 101

• an aquifer is geologic media that can yield economically usable amounts of water.

• Fill in the definition in your notes

what is an aquifer?Dirt and rocks

Depends onwho’s using it

Page 15: Aquifers 101

Aquifers have certain properties:

Limestone (especially karstified), sandstone, sand, gravel, fractured rocks

It must have spaces that water can fill up; These spaces are called pores. We call these

Materials porous. (The related noun is porosity)

It is measured by volume of space/total volume of material.

Page 16: Aquifers 101

Porosity is determined by:

1. Shape - Well rounded particles have greater porosity than angular.

ROUND ANGULAR

Porosity - The amount of space in between sediments.PO

RO

SITY

ROUNDNESS

Page 17: Aquifers 101

2. PACKING- The more closely packed the particles the lower the porosity.

UNPACKED PACKED

POR

OSI

TY

PACKING

Page 18: Aquifers 101

3. SORTING- - If all particles are the same size they are sorted. - If the particles are different sizes they are unsorted (poorly sorted) - The more sorted the higher the porosity

POR

OSI

TY

SORTING

Page 19: Aquifers 101

what is an aquifer?

For a layer to be a true aquifer, it mustAllow water to flow; if a layer lets water flow,We say its permeable. (The related noun is

Permeability.)

This is how interconnected the pores are.

Page 20: Aquifers 101

Permeability Ability of water to pass through Affected by: packing and particle size Tighter packing and Smaller particles =

less permeability Looser Packing and

Larger particles = more permeability

PER

MEA

BIL

ITY

PARTICLE SIZE

Page 21: Aquifers 101

Other things about Permeability

Permeability Rate – How fast a fluid can flow through a material

Impermeability (not permeable) is due to:

A. Tightly packing of particlesB. Cementing of particles by clayC. Cementing of particles by ice

Page 22: Aquifers 101

GRAVEL Rapid

drainage

 FINE SANDModerate drainage

 CLAYSlow

drainage

PERMEABILITY

Page 23: Aquifers 101

Clay is impermeable – water will not flow through easily

Page 24: Aquifers 101

• Another characteristic of most aquifers is the presence of layers that don’t let water flow easily.

• an aquitard is geologic media that can not yield economically usable amounts of water.

what is an aquitard?

Page 25: Aquifers 101

• clay, shale, unfractured dense rocks• Note: can still transmit water,

but s l o w l y

what is an aquitard?

Page 26: Aquifers 101

• A confining layer is an aquitard that bounds an aquifer.

what is a confining layer?

Page 27: Aquifers 101

• The vadose zone is the unsaturated geologic media between the water table and the land surface.

• Scientific side note: There is a saturated capillary zone between the vadose zone and the water table.

what is a vadose zone?

Page 28: Aquifers 101

the vadose zone

Page 29: Aquifers 101

• A water table is where the aquifer meets the vadose (unsaturated) zone.

• Scientific definition: surface on which the fluid pressure in the pores of a porous medium is exactly atmospheric.

what is a water table?

Page 30: Aquifers 101

the water table

Page 31: Aquifers 101

• Recharge is water that infiltrates to the water table of an aquifer.

what is recharge?

Page 32: Aquifers 101

recharge

Page 33: Aquifers 101

• A water level is the level at which water rests (or would rest) in a well.

what is a water level?

Page 34: Aquifers 101

the water level

Page 35: Aquifers 101

• water flows downhill (to lower potential energy)

• water flows uphill to money

2 rules of groundwater flow

Page 36: Aquifers 101

water flows downhill (to lower potential energy)

Page 37: Aquifers 101

Groundwater Flowpaths

Page 38: Aquifers 101

• An unconfined aquifer is an aquifer that is bounded by a confining layer at its bottom but not at its top.

what is an unconfined aquifer?

Page 39: Aquifers 101

an unconfined aquifer

Page 40: Aquifers 101

• A confined aquifer is an aquifer that is bounded by confining layers at its bottom and top and where the water level rises above the top of the aquifer.

• Scientific side note: This is also an artesian aquifer. “Artesian” does not require water to flow at land surface.

what is a confined aquifer?

Page 41: Aquifers 101

a confined aquifer

Page 42: Aquifers 101

confined or unconfined?

Page 43: Aquifers 101

confined or unconfined?

Page 44: Aquifers 101

confined or unconfined?

Page 45: Aquifers 101

same aquifer: unconfined and confined

Page 46: Aquifers 101

Major aquifers

Page 47: Aquifers 101

same location: confined and unconfined aquifers

Page 48: Aquifers 101

Outline

• Yay for aquifers!• Definitions• Flow through an aquifer• Pumping an aquifer

Page 49: Aquifers 101

Recharge

Aquifer

Pumping

Spring/baseflow

Your aquiferas a bathtub

Page 50: Aquifers 101
Page 51: Aquifers 101

Edwards Group

Upper Trinity aquifer

Middle Trinity aquiferGuadalupe

River

CanyonLake

Edwards aquifer(BFZ)

SE model boundary

No flow

No flow

A

A’

2400

2200

2000

1800

1600

1400

1200

1000

800

600

400

200

sea level

Spring flow

0 5 10 15 mi

Recharge

Cross-formational flow

Surface water-groundwater interaction

Groundwater flow

DrainPumping

cross-section - structure

Page 52: Aquifers 101

Recharge

Aquifer

Pumping

Spring/baseflow

Your aquiferas a bathtub

Page 53: Aquifers 101

recharge

Page 54: Aquifers 101
Page 55: Aquifers 101

Graphic from Playa Lakes Joint Venture

Page 56: Aquifers 101

Attack of theKillerSalt Cedar!


Recommended