Groundwater Flashcards
What happens to water in the soil?
Fills up spaces between soil particles (pore spaces).
List the 6 factors which cause variations in the volume of groundwater.
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
Where do low rates of infiltration occur?
Steep hillslopes, bare and stony ground
What happens to runoff and infiltration in heavy rain?
More water infiltrates exceeding the soil’s ability to absorb and the excess becomes overland flow (runoff)
Identify the problems of overland flows and indicate how they can be reduced.
It undercuts hills causing mass wasting and roughens the surface of the landscape. Terracing can slow the speed of the water.
Define the term infiltration capacity.
The ability of the soils and rocks to absorb water based on the pore spaces between the particles.
How does water move through the soil?
Under the influence of gravity by a process called capillary action
Where is capillary water held?
Between soil particles (pore spaces)
Identify the barriers to groundwater movement.
By impervious rocks and soil (clay or where water has already filled capillary spaces.)
Define aquiclude.
Impervious or impermeable layers.
Define discharge.
Water feeding springs or streams
Define recharge.
Water enters a groundwater basin.
Define aquifer.
Area of soil or rock containing groundwater
Define zone of Aeration
Area above the water table where air still fills pore spaces
Define saturated zone.
Area below water table where water saturates capillary spaces
Define water table?
The level at the top of the saturated zone
Where is the water table highest and lowest?
Highest under hills and mountains
Lowest in valleys due to percolation and seepage
Compare fine-grained to coarse-grained soils and rocks in relation to the water table.
Coarse soils such as sand, water permeates quickly
Fine soils such as clay, water permeates slowly
What are impermeable or impervious rocks and provide examples?
Rocks of high density lacking capillary spaces such as volcanic rocks like granite
Comment on the movement of groundwater.
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.
What affects the rise and fall of the water table?
Heavy rain causes it to rise
Drought causes it to fall
Name 7 Australian artesian basins.
Desert Gulf North West Perth Eucla Murray Great Artesian Basin
When does water become groundwater?
When water infiltrates the soil and beds of streams and lakes.
Describe the influence of water in subterranean landscapes (karst).
Rainfall absorbs CO₂ forming weak carbonic acid. This chemically weathers and widens joints and fractures forming caves.
Describe the characteristics of limestone.
Formed from CaCO₃, impermeable
List 4 features of karst landscapes.
Caves
Dolines (sinkholes)
Stalactites
Stalagmites
Explain the importance of groundwater to human activity.
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
How is groundwater accessed?
Natural wells; sub-artesian and artesian bores (hydrostatic pressure)
Identify some pollutants of groundwater.
Microorganisms and pathogens
Define the term potable water.
Safe and pleasant to drink
Distinguish between artesian and sub-artesian water.
Sub-artesian is pumped to the surface while artesian rises under hydrostatic pressure
Where does the Water Corporation continue to pump water from?
The Gnangara Mound
What is the Gnangara Mound?
A shallow, unconfined aquifer
Where is the Gnangara Mound located?
The northern suburban and outer northern Perth.
What is the water provided by the Gnangara Mound used for?
Use in the Perth residential and commercial distribution network.
How much of the domestic supply comes from the Gnangara Mound?
60%
Since when, the Western Australian Water Corporation has accessed water from where for what reason.
1998
The Yarragadee aquifer
A drought contingency measure
Over the last few years, what has the Water Corporation been investigating?
The potential to develop the Yarragadee aquifer as a major source of domestic supply.
What is the Yarragadee aquifer?
A partially confined, deeper aquifer underlying the Swan Costal Plain.
Where is the Yarragadee aquifer located?
It extends from Yanchep in the North to Bunbury and Augusta in the South.
In the last month, what has the state government decided?
Against the development of the Yarragadee and in favour of a second desalination plant.
