the water retained in the pore spaces of rocks below the water table
1 of 24
Porosity
volume of pore space (or volume of pore spave divided by total volume of rock if as a percentage)
2 of 24
Permeability
the rate at which fluid flows through rock
3 of 24
4 factors affecting porosity?
NOT GRAIN SIZE. Sorting (well sorted high porosity), amount of diagenesis (more compact less porous), Grain shape (round grains higher porosity), Packing and way the grains fit together.
4 of 24
Factors affecting permeability?
Good interconnections between pores, Grain size, more course the grains the better permeability.
5 of 24
Water table
The surface separating unsaturated rock above from saturated rock below.
6 of 24
Hydrostatic pressure
Pressure at a point in a body of water due to the weight of the overlying water column.
7 of 24
Hydraulic gradient
Difference in hydrostatic pressure between two points divided by distance between them.
8 of 24
Aquifer
A body of porous and permeable rock capable of storing and yielding significant amounts of water.
9 of 24
Recharge Zone
the area of an aquifer open to the atmosphere allowing replenishment of water.
10 of 24
Unconfined Aquifer
Open to the atmosphere, under atmospheric pressure and recharged by rain water
11 of 24
Confined Aquifer
Covered by impermeable rock, under hydrostatic pressure, can only be replenished if there is a recharge zone.
12 of 24
Aquiclude
An impermeable rock that doesn't transmit water.
13 of 24
Live and fossil aquifers
live: currently being replenished by rain water. Fossil: no longer being replenished and represent past wetter climate.
14 of 24
Artisian Basin
Large syncline, confined aquifer
15 of 24
Artisian Well
When a borehole is sunk into an Artisian Basin
16 of 24
Draw down
difference between water table and water level in well.
17 of 24
Problems from ground water abstraction
Lowering of water table, subsidence at surface, saltwater enchroachment
18 of 24
Threats to groundwater supply
Over-pumping, pollution
19 of 24
Advantages of SURFACE water supply
easy to abstract, Water can be treated and returned, Dams can be use for energy, resivoirs can be used for recreation
20 of 24
Disadvantages of SURFACE water supply
Water needs treatment, seasonal, Requires construction of dams, Requires flooding, Reservoirs silt up, requires sufficient rainfall
21 of 24
Advantages of GROUND water supply
Rocks act as filter, no loss due to evaporation, no requirement of expensive dams, if artesian pumping cost is low
22 of 24
Disadvantages of GROUND water supply
Requires sedimentary rocks, subsidence at surface, pollutants have long residence time, pumping costs (vertically), groundwater isn't always suitable for drinking.
23 of 24
Renewable resource/ sustainable
Renewable is one that is replenished by natural resources faster than it is being used. This is sustainable.
24 of 24
Other cards in this set
Card 2
Front
Porosity
Back
volume of pore space (or volume of pore spave divided by total volume of rock if as a percentage)
Comments
No comments have yet been made