Wet Rocks
Groundwater professional development for teachers
WORKING DOCUMENT - EXERCISES
Version 8 Mar 2010.
Teacher Earth Science Education Program
http://www.tesep.org.au/default.htm
Release Version 1.0
March 2010
Student Activity
1. Explain why people cannot rely on surface water alone for their
water supply.
2. How is evaporation different to evapotranspiration?
3. What is groundwater and why is it an important resource?
4. What is the difference between the unsaturated zone and the zone
of saturation?
5. If you were to drill a well to search for groundwater, explain how far
into the ground you would have to drill to reach your supply.
Student Activity
Making a groundwater model
It is impossible to travel underground to learn about groundwater. Models
are created to help us understand what we can’t see or experience firsthand. You are going to make a simple physical model of a groundwater
system.
Materials:
2 or 3 250ml beakers or jars
water bottle, spray bottle or extra beaker
pea-sized aquarium gravel or sand – light colours are best
blue food colouring
pump from liquid hand washing soap or similar device
a stirring rod
Setting up the model:
Make sure that your clothes are protected from the food dye.
Working in pairs fill one beaker with water. Add one drop of blue
dye.
Place the gravel or sand in the other beaker (if you have a selection
of sands and gravels you could build this up in layers).
Half fill the gravel holding beaker with water so that the top of the
gravel/sand is above the water level. The gravel and sands
represent the aquifer in this model and the base of the beaker
represents solid rock.
Observe as the water moves down through the gravel, travelling
through the spaces between each particle of gravel. Notice how the
bottom of the beaker acts just like solid rock or clay and stops the
water from infiltrating any further.
Recording observations:
Look at the gravel in the upper part of the cup.
1. Are the spaces between the gravel or sand filled with water or air? How
do you know?
2. Draw a diagram of your observation and describe the zone you can see
here.
Now look at the bottom half of the cup and observe how the water fills
every space between the gravel particles. The air that used to occupy
those spaces has been pushed out by water.
3. There are a couple of names that can be applied to this zone. What are
they? Extend your diagram to include this zone.
4. What is found at the boundary between the two zones? Mark this on
your diagram.
Find the water table “line” on your model. In a few minutes we will change
where the water table is located by pumping.
5.What will happen to the water table when you start to use the pump?
To get water out of the ground we often dig a hole, called a well, and use a
pump to draw the water out of the aquifer. Using a stirring rod or your
finger “drill a well”, by making a hole into the gravel or sand. Place the
pump into the hole. Be sure the tube reaches down into the groundwater.
Begin pumping groundwater out of your aquifer. Pump it into another cup.
6. What happens to the water table as you pump?
7. What would happen if you kept pumping?
Keep the systems going by adding a little more water to the aquifer by
“raining” on it with your water bottle.
8. Describe what is happening? Can you keep pumping now?
Conclude this exercise by summarising and include the words sand,
gravel, aquifer, unsaturated zone, zone of saturation, water table, pump
and well.
Student Activity
Grain size and porosity
Aim: To investigate the porosity of sediments with different grainsizes.
Materials and procedure
 An assortment of gravel, beads, metal balls, plasticine, sand, rice
and anything else from the lab that represents rounded to angular
grains and gravels of different sizes.
 Each pair will need three beakers that can be filled with a mixture of
the grains and gravels and a measuring cylinder or another beaker.



Select from the materials provided. Fill one beaker so that there is a
lot of space between the grains (use coarse or large sizes). Fill the
next beaker so that there is a minimum of space between the grains
(use fine grains). Fill the last beaker with a mixture of different size
materials.
Make sure that each beaker is filled to the same level.
Fill your measuring cylinder with water. Each time, record how
much water is in the cylinder at the start and how much is left at the
end, after you have filled the beaker with the sediments in it. Make
sure that you fill each beaker to the same level.
Grain size
Water level
on
measuring
cylinder
(ml) -start
Water level
on
measuring
cylinder
(ml) - end
Total
volume of
water
between
grains
(ml)
Coarse
Fine
Mixture
1. Which beaker held the largest volume of water?
2. Which beaker held the smallest volume of water?
3. From your observations and the volumes of water held in each beaker
what can you conclude about the relationship between the grainsize of the
sediments, the size of the spaces in between the sediments and the
volume of water that can be held between the sediments?
4. If these sediment types were found as rock units underground, in which
sediment type do you think you would find the most groundwater and why?
For groundwater to be able to get into a rock with good porosity it must
also have good permeability. For a rock to be permeable and for water to
move through it, the pore spaces between the grains in the rock must be
connected. Permeability is therefore a measure of the ability of water to
move through a rock.
Figure 9: Examples of
permeability
In the container on the
left, even though there is
good porosity, the
cement blocks the pore
space between the grains
and the water at the
bottom cannot flow to the
top – the pores are not
connected. In the container on the right, there is nothing to stop the flow of
water - the pores are all connected.
Student Activity
Groundwater movement – Permeability and water flow rate
Aim: To discover the rates at which water moves through different types of
sediments.
Materials: (You may need to work in groups depending on the number of
materials available)
 Three 2 litre (or 1 litre) soft drink bottles.
 Stockings or cloth, rubber bands and labels or pens.
 A 200 ml beaker for measuring the water.
 A large measuring cylinder or beaker to catch the water that
percolates through each bottle.
 Samples of clay, coarse sand, fine sand, gravel, and top soil or
graduated sizes of plastic beads.
 A stopwatch or timer.
Procedure:
 Cut the bottom off each soft drink bottle.








Secure a piece of stocking or material to the neck of each bottle
with a rubber band.
Place different size grains or beads in each bottle until the bottle is
about half full [i.e. one bottle with a coarse (large) grain size, one
medium and the other, small or fine]. You might find a way to
suspend the bottle or have someone in the group hold it for you.
Label each bottle
Make sure all bottles are filled to the same level.
Measure 200 ml of water into the beaker.
Position the measuring cylinder under the bottle opening and pour
the water into the bottle with the coarse sediments. START the
timer when you start pouring the water.
Time how long it takes for the first drop of water to come through
the bottle opening and record this in the results table. At the end of
two minutes, observe and record the volume of water that has come
through the bottle and into the measuring cylinder or beaker.
Repeat this procedure for the other two samples.
When you have finished, clean up and make sure that you do not tip
sediments down the sink. Put them in separate buckets to dry out.
Results:
Sediment
type
Time (s)
start
Coarse
0s
Medium
0s
Fine
0s
Time (s)
Volume of water
First drops in beaker or
out of bottle measuring
cylinder after 2
mins (ml)
Rate of water flow
=
volume/time
(ml/s)
1. Did the water flow all the samples at the same rate? Explain why this
might be so.
2. Describe the relationship between the rate at which water passed
through the sediments and the size of the grains.
3. Which soil sample is the most permeable (allows water to flow through
the fastest)?
4. Which soil sample is the least permeable?
5. If you mixed the gravel and clay together, would the rate of water
moving through the soil be faster or slower than the clay alone?
Conclusion: Summarise what you now know about permeability and grain
size from your experiment. Refer back to the Aim in your conclusion.
Student Activity
1. Name four factors that are said to change the porosity of a rock.
2. Look back at figures 10 and 11. Why is a rock made up of well
sorted grains more porous than a rock that has poorly sorted
grains?
3. Explain the difference between porosity and permeability.
4. In a few sentences, compare an aquifer to an aquitard. How can
they work together to supply groundwater?
Student Activity
Water table contouring activity
If the level of the water table in a number of boreholes in the same area is
known, then using these points we can make a contour map of the water
table. This is convenient if you want to drill a borehole or well and you want
to know how far down the water table is in your area.
On the map below (birds-eye view), there is an extinct volcano, a
permanent lake and a permanent stream. The dots represent piezometers
– boreholes in the ground used to observe the level of the water table. The
levels of water (in metres above sea level) are shown next to each
borehole).
Procedure:
1. Look at Figure 11 of the confined aquifer.
2. Where are the recharge areas and the discharge areas? High or low
ground?
3. On your map mark the recharge and discharge areas.
4. Contour lines join areas of equal value. Using lines with values from 90
to 150m draw water table contours on your map (the 105 and 130m lines
have been done for you).
130
Lake
130
Waterway
115
Bed
elevation of
waterway
120
Bore with
elevation of
groundwater
130
Groundwater
elevation
contour
125
125
122
120
123
122
119
130
115
118
115
127
130
119
110
123
108
107
105
112
105
105
105
EXERCISE: Draw in the groundwater contours at 5 m intervals. The 130 and
105m groundwater contours have been drawn in for you. Where is the
groundwater likely to flow into the waterway (ie the elevation of the
groundwater is greater than the bed level of the waterway).
Student Activity
1. Role Play: Stoush brewing over bottled water
See Additional materials section for full transcript and background for
this activity.
Work in groups of 4 to 6 and read the transcript. Everyone has a different ‘role’ to
play.
KERRY O'BRIEN – 7.30 Report
JONATHAN HARLEY – 7.30 Report
ALEC WAGSTAFF - CORPORATE AFFAIRS, COCA-COLA AMATIL
MARGARET PONTIFEX - MANGROVE MOUNTAIN DISTRICTS COMMUNITY
GROUP
DR NOEL MERRICK – NATIONAL CENTRE FOR GROUND WATER
MANAGEMENT
MALCOLM BROOKS - MAYOR, GOSFORD CITY COUNCIL
Discuss the different issues raised; continue role-play into debate with each
stakeholder represented and their position argued for.
What does this example say about the Ownership of water?
What level of management should government hold in monitoring industries?
Student Activity
Read the following poem as a class or in pairs.
1. What does this poem say about attitudes to groundwater 100 years ago?
2. How has this attitude changed over time?
3. Write a poem or short creative piece that responds to current perceptions
of groundwater.
4. Explain why YOU think groundwater needs to wisely used and managed.
Song Of The Artesian Water – Banjo Patterson
Now the stock have started dying, for the Lord has sent a drought,
But we're sick of prayers and Providence - we're going to do without,
With the derricks up above us and the solid earth below,
We are waiting at the lever for the word to let her go.
Sinking down, deeper down,
Oh, we'll sink it deeper down:
As the drill is plugging downward at a thousand feet of level,
If the Lord won't send us water, oh, we'll get it from the devil;
Yes, we'll get it from the devil deeper down.
Now, our engine's built in Glasgow by a very canny Scot,
And he marked it twenty horse-power, but he didn't know what is what.
When Canadian Bill is firing with the sun-dried gidgee logs,
She can equal thirty horses and a score or so of dogs.
Sinking down, deeper down
Oh, we're going deeper down:
If we fail to get the water, then it's ruin to the squatter,
For the drought is on the station and the weather's growing hotter,
But we're bound to get the water deeper down.
But the shaft has started caving and the sinking's very slow,
And the yellow rods are bending in the water down below,
And the tubes are always jamming, and they can't be made to shift
Till we nearly burst the engine with a forty horse-power lift,
Sinking down, deeper down,
Oh, we're going deeper down:
Though the shaft is always caving, and the tubes are always jamming,
Yet we'll fight our way to water while the stubborn drill is rammingWhile the stubborn drill is ramming deeper down.
But there's no artesian water, though we're passed three thousand feet,
And the contract price is growing, and the boss is nearly beat.
But it must be down beneath us, and it's down we've got to go.
Though she's bumping on the solid rock four thousand feet below,
Sinking down, deeper down,
Oh, we're going deeper down:
And it's time they heard us knocking on the roof of Satan's dwellin',
But we'll get artesian water if we cave the roof of hell inOh we'll get artesian water deeper down.
But it's hark! the whistle's blowing with a wild, exultant blast,
And the boys are madly cheering, for they've struck the flow at last:
And it's rushing up the tubing from four thousand feet below,
Till it spouts above the casing in a million-gallon flow.
And it's down, deeper downOh, it comes from deeper down:
It is flowing, ever flowing, in a free, unstinted measure
From the silent hidden places where the old earth hides her treasureWhere the old earth hides her treasures deeper down.
And it's clear away the timber and it's let the water run,
How it glimmers in the shadow, how it flashes in the sun!
By the silent belts of timber, by the miles of blazing plain
It is bringing hope and comfort to the thirsty land again.
Flowing down, further down:
It is flowing further down
To the tortured thirsty cattle, bringing gladness in its going;
Through the droughty days of summer it is flowing, ever flowingIt is flowing, ever flowing, further down.
New South Wales
Case Study 1 Groundwater for agriculture: Namoi Catchment
Source: http://www.environment.nsw.gov.au/ieo/Namoi/map.htm
The Namoi Valley, in the north west of NSW stretches from Quirindi and
Tamworth in the east, to Wee Waa and Walgett in the west. It is considered a
key area of groundwater for agriculture. Managing both the surface and
groundwater resources in this region is complex. Groundwater is managed
according to NSW Government objectives which aim to improve water quality
and the reliable flow of water from rivers in the whole catchment.
Agriculture in the valley is as diverse as the landscape. Irrigation is concentrated
in the regulated sections of the valley, with water also being sourced from
underground. Irrigated agriculture covers just 1.5% of the area of the catchment
but contributes 32.3% of total production. Major irrigated commodities in the
Namoi valley are cotton, pastures for stock feed and cereals.
Across the valley, agriculture is the largest employer providing jobs for 6,634
people, about 17.3% of the total population.
Student Activity
1. Look at the map of the Namoi River Catchment. Describe the size and location
of forested land and national parks in the catchment. Give two reasons to explain
why water is needed to maintain ecosystems? Where do you think this water
might come from?
2. Give two reasons to explain why farmers in this region might have to source
some irrigation water from under the ground.
3. Some rivers in the area are “controlled with reduced flow”. What do you think
this means? What implications might this have for the farmers in the catchment?
New South Wales
Case Study 2 Groundwater Contamination, Botany Bay Aquifer
What is the Botany Sands Aquifer?
The Botany Sands Aquifer is a large volume of underground water present in the
sandy ground surrounding Botany Bay. The aquifer is relatively shallow, easily
accessible by shallow drilling techniques. The natural quality of the water is very
good. Significant volumes of drinking quality water were available. However, as
the area receives reticulated water as part of the Sydney supply system, most
use was for watering gardens and for industry.
Groundwater from the Botany Sands aquifer discharges to Botany Bay. As a
result, any contamination that is in the groundwater has the potential to impact on
the environment within the Bay.
The aquifer is highly vulnerable to contamination due to the permeability of the
sands, and the generally shallow water table. Any contamination from land use
activity that escapes or is spilled onto the ground is likely to accumulate in the
earth and leach into the groundwater.
How was the groundwater contaminated?
Botany and its surrounding suburbs have been heavily used by industry for at
least 100 years. This was largely before any environmental controls were in
place and basic measures to prevent pollution were not considered. This legacy
is what we are now dealing with, in Australia and around the world.
A range of industries operated in the Botany area such as tanneries, metal
platers, service stations and depots, landfills, dry cleaners and wool scourers. As
a result, chemicals such as chlorinated hydrocarbons and other solvents,
petroleum hydrocarbons (such as petrol and diesel), and some heavy metals
such as chromium, nickel, lead and arsenic, may have contaminated the aquifer.
Four of these most significant sites of contamination have been cleaned up and
the remaining four are either in the process of being cleaned up or have a site
plan in development. However, given the history of the area, shallow water table
and highly permeable soils, a precautionary approach to managing groundwater
in the area is needed.
Area affected by contaminated groundwater, Botany Bay.
Student Activity
Planning for the future of the Botany Sands Aquifer.
Congratulations!
Your team of three have been selected to plan for the future of the Botany Sands
Aquifer.
Your task is to plan and present a PowerPoint OR a drama production which
explains your plans for the future of this important resource.
You must include the following in your report:
 Map showing the location of the Botany Sands Aquifer in Australia and
New South Wales. A short description of location is also needed
 A brief history of the USE of the aquifer
 Explanation about how former land uses, primarily industry, have resulted
in contaminants harmful to human health entering the groundwater over a
very large area
 Description of CURRENT USE of the groundwater
 An assessment about risk that people can be exposed to via
contamination when they use water from this source. Make a judgement:
is the risk high/moderate/low. Give reasons for your choice
 A FUTURE PLAN for the use and management of the Botany Sands
Aquifer.
Your team should consult internet resources for help. Two useful starting points
are:
Additional material for NSW Case Study 2
Groundwater contamination Botany Bay Aquifer in this kit
http://www.naturalresources.nsw.gov.au/water/botany_bay.shtml
Groundwater contamination Botany Bay Aquifer
Australian Broadcasting Corporation
TV PROGRAM TRANSCRIPT
LOCATION: http://www.abc.net.au/7.30/content/2006/s1722507.htm
Broadcast: 23/08/2006
Sydney introduces ground water ban
Reporter: Jonathan Harley
KERRY O'BRIEN: You might be forgiven for thinking that years of industrial
pollution is catching up with Sydney. After months of scandal surrounding the
toxic contamination of Sydney Harbour's fish stocks, there is now another
alarming chapter in the story of the city's lingering industrial pollution. Tens of
thousands of Sydney residents have been told not to use ground water at all as
decades of industrial contamination spread through the water table beneath
Sydney's eastern and, to some extent, southern suburbs. The ban is all the more
alarming because State authorities and the industrial giant at the centre of the
pollution had promised to clean it all up. Jonathan Harley reports.
JONATHAN HARLEY: For the past three years, Manuel Spanis had been
relying on ground water to keep his garden and vegie patch alive. As water
restrictions tightened in the face of Sydney's drought, Manuel Spanis saw the
water beneath his feet as free, plentiful and, so he believed, clean.
MANUEL SPANIS, BOTANY RESIDENT: I think that the water is very clean.
Very clean, the water. Not salty. Not for the drink. For the grass, alright.
JONATHAN HARLEY: But now Manuel Spanis must confront a toxic truth
which has spread to his suburb. And you've watered all of this with ground
water?
MANUEL SPANIS: Oh, yeah.
JONATHAN HARLEY: A chemical cocktail that's contaminated the ground
water and spread much further than previously thought. His household is one of
around 16,000 which have been told not to use ground water for anything, even
watering the lawn.
IAN McDONALD, NSW NATURAL RESOURCES MINISTER: Well, I think
over time there could be some impacts on humans. We know that heavy metals
and that do have a negative impact upon human health. So we are doing this as a
precautionary step to ensure that people aren't using it in swimming pools or on
their vegie patches or drinking it.
JONATHAN HARLEY: Manuel Spanis lives down the road from Botany Bay,
the birthplace of modern Australia and today the nation's busiest airport
gateway. But its foreshore has been Sydney's industrial heartland. It's here that
everything from pesticides to chlorine has been produced and from there poison
has leached into the water table.
JOE WOODWARD, I believe this would be the most serious ground water
contamination issue in Australia.
JONATHAN HARLEY: 18 months ago, the 7:30 Report highlighted the ground
water contamination from this Orica chemical site and at that time residents
were assured that the pollution was strictly contained. Of course, we now know
those assurance were dangerously wrong.
DANNY KENNEDY, GREENPEACE: They're meant to be the regulator,
they're meant to be watching out for the public interest here, and the EPA and
others have been asleep at the wheel. Not doing the testing, not drilling the
ground water sample bores, not doing the work to find out the true extent of this
pollution that we have known about for 15, 20 or more years.
JONATHAN HARLEY: But people were told repeatedly that this ground water
contamination was localised around the Orica site near here, near Botany Bay.
Can you understand people being frustrated when they find that there's serious
contamination right below their houses? IAN McDONALD, NSW NATURAL
RESOURCES MINISTER: Well, there is pollution underneath their houses in
the aquifer, in certain areas, which were primarily heavy industrial areas for over
150 years. There's no doubt that it's there. We are testing and trying to get a
pattern of it.
JONATHAN HARLEY: The underground contamination was thought to centre
on the suburbs of Banksmeadow and Botany in and around the Orica site. But
almost overnight residents in 13 other suburbs have learned their ground water is
also contaminated. This toxic footprint now spreads more than 6km further than
was first thought.
DANNY KENNEDY, GREENPEACE: It has spread to a far greater range than
we previously expected. It's actually surprised us how far wide it's gone and also
who knows how long these people have been exposed to these pollutants?
JONATHAN HARLEY: After years of sustained pressure from residents and
environment groups, Orica recently started pumping up contaminated ground
water and treating it. Both the company and State Government say this newly
publicised pollution is upstream from Orica and therefore not its fault.
ARCHIVE NEWS STORY: This sort of out of sight, out of mind operation is
better than most but no guarantee against seepage and it raises the question of
what dangers we may be storing up beneath our feet for the future.
JONATHAN HARLEY: Blame is being sheeted to a century and a half of ad
hoc unregulated industry.
IAN McDONALD: Well, this area was a long-term industrial use site and there
have been many companies active there over 150 years and tanneries and wool
scourers, petroleum companies all releasing and leaching into the sands of the
aquifer and a large number of twin chemicals from heavy metals, such as
arsenic, vinyl chloride, many hydrocarbons.
JONATHAN HARLEY: Such chemicals might have hardly seen the light of day
if not for the sharp rise in households plumbing the ground water because of
recent water restrictions. As many as 2,000 homes in this area have put in bores
and most of them like Manuel Spanis have done so without a licence. What's
going to happen in summer?
MANUAL SPANIS: I don't know. Stop it.
JONATHAN HARLEY: There's no way you will use this water again? No.
MANUEL SPANIS: If they say no, you can't use it.
JONATHAN HARLEY: Provided residents observe the ban, the contaminated
ground water will again be out of sight, but there remains the longer question of
whether a massive clean-up operation will be needed. It seems to be a recurring
theme in Sydney as is the matter of who will ultimately foot the bill.
IAN McDONALD: The clean up could be a very, very extensive cost to the
taxpayer because a lot of these companies, for instance, had been operating in
there since the 1860s and a lot have gone. There's no legal entity one could
pursue in many of the instances of activity that has gone on in the past. It will be
a government responsibility to deal with in the end.
KERRY O'BRIEN: So be it.
Case Study 3 Groundwater Dependent Ecosystems, Blue Mountains.
The Importance of Blue Mountains Swamps
Blue Mountains Swamps are a biologically diverse plant community that occurs
nowhere else in the world. Blue Mountains swamps play a vital part in
maintaining the water flows in the area’s creeks and waterfalls, by storing water
and slowly releasing it over time. Swamps also act as filters, purifying water prior
to release into creeks. There are less than 3,000 ha of Blue Mountains Swamp
in existence. As they predominantly comprise many small areas, they are very
susceptible to edge effects. As the urban footprint expands to the edges of the
plateau, the swamps are coming under ever increasing pressure.
The predominant threats to Blue Mountains Swamps include:




Changes in land use from forests to urban areas
Changing surface run-off associated with Clearing for urban development
Modification of forest cover through fire (both ‘wild’ and hazard reduction)
Water extraction (bores, tapping natural springs and building dams)
What are Hanging Swamps?
Generally swamps are expected to occur in low lying flat areas with poor
drainage. However Blue Mountains swamps often ‘hang’ on steep valley sides
where logic would suggest they shouldn't be able to occur. They are able to form
because of the unique geology of the upper and mid Mountains. Rainwater
penetrates the soil and then starts to seep through the permeable Narabeen
sandstone layers. However when the water reaches the thin layers of
impermeable claystone and ironstone interspersed among the thicker layers of
Narabeen Sandstone the vertical passage of water is impeded resulting in the
water being shunted sideways. Where the impermeable layers outcrop on the
valley sides the groundwater trickles out continuously providing the constant
moisture required to maintain swamp vegetation.
Over millennia the peaty swamp soils develop from the decay of the swamp
vegetation and start extending down the slope. Have a look at a hanging swamp
from a distance and often the distinctive line of the impermeable claystone layer
can be seen at the top of the hanging swamp.
Student Activity
1. Read the following and then answer the question below.
Changing land use affects recharge – that is the amount of water that enters
the groundwater. As the hanging swamps are dependent on the amount of
groundwater that flows OUT of the system, changing how much goes IN
affects the overall flow. In some cases, the replacement of native vegetation
with paved areas and drainage of an urban development can REDUCE the
amount of recharge. Changing land-use can also change the QUALITY of
recharge. For example, under agriculture or even urban use, the use of
fertilisers and pesticides can result in residual nitrates and pesticides entering
the groundwater. Swamp vegetation may react to the changed quality. Both
effects can impact swamp health.
2. Explain why changing the way the land is used on the surface of the earth
affects what happens beneath it.
3. What does this tell you about the connectedness of surface landuse, surface
water and groundwater?
4. How does pumping groundwater affect the health of hanging swamps?
5. Why is it important to sustain the health of the hanging swamps?
Queensland Case Study
Groundwater for Irrigation Lockyer Valley
The Lockyer Valley is a roughly circular basin of approximately 2,800 km2 in
southeast Queensland. The town of Gatton, population 4,600, is the largest in the
valley and is 90 km west of the state capital, Brisbane.

Where does the groundwater come from?
The groundwater that is used for irrigation is mainly from the alluvial
aquifers. This water mostly comes from the surrounding ranges, by
surface flows and groundwater seepage into the Lockyer catchment
streams. It then recharges the alluvium. There is only minor direct
recharge to alluvium by rainfall in the valley.

Does water from irrigation soak back into the aquifers?
This seems to vary quite a bit in the valley, but studies show that most of
the central valley has silts and clays at shallow depth. Here vertical
infiltration is restricted at around 60 to 100 cm (0.6 to 1.0 m) by these finegrained layers. This is probably the case for most of the wider parts of the
alluvium, but may decrease in the sub catchments.

Is there plenty of water left in the alluvial aquifers?
Not at the moment. The amount of available, usable groundwater depends
on recharge from rainfall, how much is extracted, and how much is lost by
evapotranspiration.

Do the aquifers recharge from the Downs?
The alluvial aquifers seem to mainly recharge from nearby ranges. There
is slow recharge of much older water to the sandstone bedrock, and this is
no doubt sourced partly from the Downs.

Do some parts of the valley get better recharge than others?
Yes. This can vary quite a bit, and is usually associated with the valley
morphology (shape and height of hills) which does influence the amount of
rainfall.

If there was no irrigation, where would groundwater move into the
valley, and where would it flow to?
Under natural conditions water from the ranges would flow into the
network of streams around the catchment, and flow along them to the
main central creek system. This water would recharge the alluvium as it
flowed. If there was enough water the creeks would continue flowing. By
nature, however, the Lockyer is an ephemeral drainage system, i.e. only
flows after rainfall. Under conditions of no extraction, it is likely that there
would be continual groundwater flow within alluvium, into the Brisbane
River. A lot of water would be lost along the way by evaporation, and
transpiration by vegetation. A natural system develops its own balance.
Student Activity
1. Use an atlas to draw a map showing the location of the Lockyer Valley.
2. Describe the location of the Lockyer Valley, referring to its direction and
distance from Brisbane.
3. Draw a map of the Lockyer Valley to show its shape and the location of the
Lockyer River.
(Hint: try http://www.lockyerwater.com/doc/dcc_detail.php?dcc_id=1)
3. Look at the map showing boreholes in the Lockyer Valley at
http://www.lockyerwater.com/doc/dcc_detail.php?dcc_id=1
Select Groundwater Studies and Further Information: distribution of bores
in the Lockyer Valley.
Describe the spatial association between the location of alluvium soils and
the location of bores in the Lockyer Valley. (A spatial association describes
the degree to which two or more phenomena are similarly arranged over
space. That is, to what degree do the two patterns match? Spatial
association is usually expressed as being a high, moderate or low degree
of correlation).
4. Explain why irrigation is important in the Lockyer Valley. What problems
could occur from taking too much water out of the aquifer for irrigation?
Western Australia Case Study
Groundwater Dependent Ecosystem Gnangara Mound
Gnangara Mound is Perth’s largest source of groundwater. It stretches from
Gingin in the north to the Swan River in the south. It is a shallow (or unconfined)
aquifer which overlays a deeper (confined) aquifer. The Gnangara Mound
supplies water for:
 Local wetlands and lakes
 Up to 60% of Perth’s drinking water
 Irrigation for horticulture and agriculture in the Wanneroo and Swan
regions
 Irrigation for public open spaces and private gardens.
Wetlands and groundwater levels on the Gnangara Mound have been under
pressure recently because of less rainfall. In addition, recharge from rainwater
has been limited because of native and pine plantations in the region. There has
also been increasing amounts of water taken from the ground for public water
use and irrigation.
This has greatly impacted on the amount of groundwater available for
ecosystems that are dependent on groundwater (Groundwater Dependent
Ecosystems GDE’s). In some parts of the Gnangara Mound, water quality has
also been affected by decreasing water levels.
The Department of Water in Western Australia manages the amount of water
taken out of the ground in order to ensure that GDE’s have enough water to be
sustained.
Source: www.water.wa.gov.au
Student Activity
1. Look at the table above. What happens to the average groundwater level
between January and December every year?
2. What has happened to the amount of water in the mound between 1997
and 2007. Use evidence from the graph to support your answer.
3. List the ways in which water from the Gnangara Mound is used.
4. Rank the uses in order of importance.
5. Give reasons for your ranking.
6. Explain why it is important that the Gnangara Mound is managed
sustainably. How can this occur when there are so many conflicting uses?
Victoria Case Study
Map2 Groundwater Resources Victoria
Source:
http://www.greenhouse.vic.gov.au/DPI/Vro/map_documents.nsf/pages/vic_
groundwater_resources
Student Activity
1. Use Map 1 to complete the following into your workbook.
2. There are ___________ groundwater basins located in Victoria. They
(are the same size/vary in size) across Victoria. The largest
groundwater basin is called the ___________________Basin. It is
situated in the (Northern/Central/Southern) region of the state. Four
smaller groundwater basins are located to the (North/South) of the
Highlands basin. These are named, in order of
area:____________________________________________________
________________________________________________________
________________________________________________________
_________________________. The Murray basin is located in the
north west of Victoria. Some towns which use the Murray Basin
groundwater
include___________________________________________________
________________________________________________________
______________.
3. Refer to maps 1 and 2. Copy and complete the following information oi
your workbook.
The map of Groundwater Resources shows five quality classes of groundwater,
based on salinity. The best groundwater is suitable for (drinking, gardens,
industry/beef cattle). This water has less than (1000 mg/L of TDS/more than
1000 mg/L TDS).
Groundwater which has salinity of greater than 7000 mg/L TDS is suitable only
for _____________________________________________. When groundwater
has a salinity level higher than 14000 mg/L TDS it is (too saline for any use/very
good to use)
Almost half of the total volume of groundwater, or about 480,000 ML, is
considered to be fresh while 35% is marginal in quality, 13% is brackish and 3%
is saline.
4. Use Maps 1 and 2 to answer True (T) or false to the following:
Groundwater quality is generally good in the eastern half of the State and
marginal in the Port Phillip region.
In the south-west, groundwater resources tend to vary from very good to
marginal quality while the smaller minor sources tend to be brackish.
Groundwater salinity causes problems in the river basins which drain to the River
Murray in the north-west quarter of the state.
Groundwater in the Gippsland basin is generally of good drinking quality.
Groundwater in the Port Phillip and western Port Basins is generally not suitable
for domestic use.
Groundwater in the Mallee and Wimmera regions is particularly saline.
5. Choose the groundwater basin in which you live. Research 5 interesting
facts about it. Compare your facts with those found by others in your class.
For information go to:
Port Phillip Basin:
http://www.land.vic.gov.au/CA256F310024B628/0/F231CA2E7B916910C
A256FF200211419/$File/GWNOTE08.pdf
http://www.dse.vic.gov.au/CA256F310024B628/0/C2BD0459E110B16FCA
256FF200202067/$File/GWNOTE04.pdf Otway Basin