ground water Flashcards
where is ground water present?
where the material of the crust has pores or fractures
what is the water table?
the level below which the ground is saturated with water
what is the worlds most important source of fresh water?
groundwater
how much of canadas population depends on groundwater?
30%
what is the boundary between unsaturated and saturated called?
the capillary fringe
what is the unsaturated zone?
air in between pores of soil
what is the saturated zone?
water filled up all pores in the soil
when does the water table rise/ fall?
with the seasons and when they change
what characteristics do ground water have that are different from surface water?
flows more slowly
harder to get water in or out
what is porosity?
The total volume of open space
where does ground water reside?
in subsurface pore spaces
what are the two types of porosity?
primary
secondary
what is primary porosity?
originally formed with the material
what are examples of primary porosity?
Voids in sediment
Vesicles in basalt
what is secondary porosity?
porosity develops after the rock is formed
what causes secondary porosity?
fracturing
faulting
dissolution
what is permeability?
The ease of water flow due to pore interconnectedness
what are characteristics of permeability?
Highly permeable material allows water to flow readily
* Water cannot flow through impermeable material
* Many large and straight flow paths enhance permeability
what is an aquifer?
sediment or rock that transmits water easily
what is an aquitard?
impermeable or low permeability sediment or rock that hinders water flow
what is unconfined aquifer?
an aquifer that intersects the surface
– In contact with the
atmosphere
– Easily contaminated
what is a confined aquifer?
an aquifer beneath an aquitard
– Isolated from the surface
– Less susceptible to
pollution
what is the hydraulic gradient?
slope of the water table
what is groundwater fed by?
snowmelt and rainfall
