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.
