Water Flashcards
Hydrostatic Pressure
Pressure at a point in a body of water due to the weight of the overlying water column
Aquiclude
An impermeable rock that doesn’t transmit water
Porosity
The volume of pore space
=(Total volume of pore spaces/total volume of rock)*100
Permeability
The rate of flow of fluids through a rock
=(Distance travelled/time taken)
Artesian Basin
A large synclinal confined aquifer from which water comes up under pressure
Hydrostatic gradient
=(height difference between two points/horizontal distance between them)
Artesian Well
A well that holds water under hydrostatic pressure
Recharge Zone
An area of an aquifer open to the atmosphere from which it can be replenished
Water table
The boundary between saturated and unsaturated rock
Aquifer
A body of porous and permeable rock that is capable of string and yielding significant amounts of water
Cone of depression
A dip in the height of the water table around a well
Draw down
Height difference between the water table and the height of water in the well
Well
A borehole that is lined with an impermeable casing and produces water
Abstraction
Removal of water from a source
Hydrostatic head
The height of the overlying water column
Problems with groundwater abstraction
Lowering of water table
Subsidence
Saltwater encroachment
Threats to groundwater supplies
Pollution
Over-pumping
Advantages of surface water
Easy abstraction
Reservoirs are multipurpose
Water can be treated after use and put back into river
Dams can be used for hydroelectric power
Disadvantages of surface water
Dam construction can cause earthquakes
Reservoirs require dredging
Building reservoirs requires flooding land
Volume of water is seasonal as it requires sufficient rainfall
Building dams is expensive
Advantages of groundwater
If artesian basin no/low pumping costs
Rocks act as a natural filter
Doesn’t need large infrastructure i.e. Dams
No loss of after through evaporation
Disadvantages of groundwater
Requires suitable geology
Water may need treatment for dissolved salts
Subsidence
Pumping costs can be expensive
Pollutants are not easily removed from aquifer
Artificial Recharge
When water is pumped into a source to replenish it
Groundwater
Water retained in the pore spaces of rocks below the water table
Types of Spring
Lithological spring - in valleys and next to igneous intrusions
Springs at a fault
Springs at unconformities
