Groundwater

Question 1

What happens to water in the soil?

Answer 1

Fills up spaces between soil particles (pore spaces).

Question 2

List the 6 factors which cause variations in the volume of groundwater.

Answer 2

Source of water
Amount and duration of rainfall
Land surface
Area of collection (catchment)
Vegetation type and formation
The types of soil and rock present

Question 3

Where do low rates of infiltration occur?

Answer 3

Steep hillslopes, bare and stony ground

Question 4

What happens to runoff and infiltration in heavy rain?

Answer 4

More water infiltrates exceeding the soil’s ability to absorb and the excess becomes overland flow (runoff)

Question 5

Identify the problems of overland flows and indicate how they can be reduced.

Answer 5

It undercuts hills causing mass wasting and roughens the surface of the landscape. Terracing can slow the speed of the water.

Question 6

Define the term infiltration capacity.

Answer 6

The ability of the soils and rocks to absorb water based on the pore spaces between the particles.

Question 7

How does water move through the soil?

Answer 7

Under the influence of gravity by a process called capillary action

Question 8

Where is capillary water held?

Answer 8

Between soil particles (pore spaces)

Question 9

Identify the barriers to groundwater movement.

Answer 9

By impervious rocks and soil (clay or where water has already filled capillary spaces.)

Question 10

Define aquiclude.

Answer 10

Impervious or impermeable layers.

Question 11

Define discharge.

Answer 11

Water feeding springs or streams

Question 12

Define recharge.

Answer 12

Water enters a groundwater basin.

Question 13

Define aquifer.

Answer 13

Area of soil or rock containing groundwater

Question 14

Define zone of Aeration

Answer 14

Area above the water table where air still fills pore spaces

Question 15

Define saturated zone.

Answer 15

Area below water table where water saturates capillary spaces

Question 16

Define water table?

Answer 16

The level at the top of the saturated zone

Question 17

Where is the water table highest and lowest?

Answer 17

Highest under hills and mountains

Lowest in valleys due to percolation and seepage

Question 18

Compare fine-grained to coarse-grained soils and rocks in relation to the water table.

Answer 18

Coarse soils such as sand, water permeates quickly

Fine soils such as clay, water permeates slowly

Question 19

What are impermeable or impervious rocks and provide examples?

Answer 19

Rocks of high density lacking capillary spaces such as volcanic rocks like granite

Question 20

Comment on the movement of groundwater.

Answer 20

It is very slow compared to runoff. It moves along a curve due to slope and gravity. Water tables rise and fall with seasonal conditions.

Question 21

What affects the rise and fall of the water table?

Answer 21

Heavy rain causes it to rise

Drought causes it to fall

Question 22

Name 7 Australian artesian basins.

Answer 22

Desert
Gulf
North West
Perth
Eucla
Murray
Great Artesian Basin

Question 23

When does water become groundwater?

Answer 23

When water infiltrates the soil and beds of streams and lakes.

Question 24

Describe the influence of water in subterranean landscapes (karst).

Answer 24

Rainfall absorbs CO₂ forming weak carbonic acid. This chemically weathers and widens joints and fractures forming caves.

Question 25

Describe the characteristics of limestone.

Answer 25

Formed from CaCO₃, impermeable

Question 26

List 4 features of karst landscapes.

Answer 26

Caves
Dolines (sinkholes)
Stalactites
Stalagmites

Question 27

Explain the importance of groundwater to human activity.

Answer 27

Underlies 60% of Australia; 5.25 million km2; 70% is suitable for domestic use and irrigation; 50% of US population depends on groundwater (95% in rural areas); Developing nations depend on groundwater

Question 28

How is groundwater accessed?

Answer 28

Natural wells; sub-artesian and artesian bores (hydrostatic pressure)

Question 29

Identify some pollutants of groundwater.

Answer 29

Microorganisms and pathogens

Question 30

Define the term potable water.

Answer 30

Safe and pleasant to drink

Question 31

Distinguish between artesian and sub-artesian water.

Answer 31

Sub-artesian is pumped to the surface while artesian rises under hydrostatic pressure

Question 32

Where does the Water Corporation continue to pump water from?

Answer 32

The Gnangara Mound

Question 33

What is the Gnangara Mound?

Answer 33

A shallow, unconfined aquifer

Question 34

Where is the Gnangara Mound located?

Answer 34

The northern suburban and outer northern Perth.

Question 35

What is the water provided by the Gnangara Mound used for?

Answer 35

Use in the Perth residential and commercial distribution network.

Question 36

How much of the domestic supply comes from the Gnangara Mound?

Answer 36

60%

Question 37

Since when, the Western Australian Water Corporation has accessed water from where for what reason.

Answer 37

1998
The Yarragadee aquifer
A drought contingency measure

Question 38

Over the last few years, what has the Water Corporation been investigating?

Answer 38

The potential to develop the Yarragadee aquifer as a major source of domestic supply.

Question 39

What is the Yarragadee aquifer?

Answer 39

A partially confined, deeper aquifer underlying the Swan Costal Plain.

Question 40

Where is the Yarragadee aquifer located?

Answer 40

It extends from Yanchep in the North to Bunbury and Augusta in the South.

Question 41

In the last month, what has the state government decided?

Answer 41

Against the development of the Yarragadee and in favour of a second desalination plant.