Chapter 9 Flashcards
Groundwater (29 cards)
Groundwater
Water below the Earth’s surface that fills spaces in regolith, soil and rock.
Pores
Spaces within rocks that groundwater is stored in.
Porosity
Proportion of pore space in a geologic medium (regolith, sediment or rock)
Permeability
Depends on porosity, size of pore spaces, and connectedness of pore spaces
Vadose zone
Zone in which air is present in a pore space
Permafrost
Pore water may be permanently filled by ice.
Water table
Vadose and saturated zones are separated by a boundary
Recharge
When water enters the subsurface and becomes groundwater
Discharge
Process that returns groundwater to the surface of the Geosphere.
Springs
Natural points of groundwater discharge that occur when the water table intersects the land surface
Gaining stream
A stream that increases flow downstream due to base flow
Losing streams
Streams may decrease in flow downstream if the water recharges groundwater
Aquifers
Units within the outermost Geosphere that have sufficient capacity and high enough permeability to supply water at a rate useful to humans
Aquitards
Units of geologic media that considerably slow or stop the flow of water
Aquicludes
Permeability so low that there is no measurable flow of water through them
Unconfined aquifer
Upper boundary is defined by the water table
Cone of depression
Drawdown cone produced by pumping water from an unconfined aquifer leads to a lowering of the water table
Confined aquifer
Upper boundary is defined by an aquitard or aquiclude
Artesian
Water in a confined aquifer may be under pressure
Karst topography
Dissolution of limestone and other soluble rock types leads to formation of cave systems, sinkholes and pillars of rock isolated by dissolution of surrounding materials.
Fresh water
<1000 ppm dissolved solids
Brackish water
1000-10,000 ppm
Saline water
10,000-35,000 ppm: same as sea water
Brine
> 35,000 ppm
