Groundwater Flashcards
Where can you find groundwater?
Where the material of the crust has pores or fractures
Unsaturated zone
Where water and air fill up the pore spaces
Saturated zone
Where water fills all pore space
The boundary between the unsaturated and saturated zones
Capillary fringe
What happens to the water table throughput seasons
It rises and falls
Where does water flow the fastest?
At the surface level
Porosity
Total volume of open space
Pores
Open spaces within any sediment or rock
Primary porosity
Originally formed with the material (voids in sediment, vesicles in basalt)
Secondary porosity
Formes later separate from the sediment itself (fracturing, faulting, dissolution)
Permeability
The ease of water flow due to pore interconnectedness
Highly permeable - allows water to flow readily, impermeable - water cannot flow through
Many large and straight flow paths enhance permeability
Aquifer
Sediment or rock that transmits water easily
Aquitard
Impermeable or low permeability sediment that stops water flow
Unconfined aquifer
Intersects with the surface in contact with the atmosphere, can be easily polluted (on top of the aquitard and connected to the surface)
Confined aquifer
Beneath an aquitard (isolated from the surface), less susceptible to pollution
Hydraulic gradient
The slope of the water table
Darcy’s Law
V=K(h2-h1)/L
V= groundwater flow velocity
K=coefficient of permeability
(h2-h1)/L=hydraulic gradient
Gaining stream
When groundwater contributes to the base flow of a stream (groundwater going to stream water)
Losing stream
When the stream is losing water to the water table or groundwater
Difference between a connected and a disconnected losing stream?
A connected stream is when the stream is connected to the water table, a disconnected losing stream has an unsaturated layer of the ground in between the stream and the water table
Why are wetlands important?
They help store surface and ground water
Hydraulic pressure
Water moves in response to gravity and hydraulic pressure (slide 21)
Hard water
Groundwater contains a wide range of dissolved ions, most at levels that are higher than in surface water, which is why “hard water” usually contains coatings of white mineral precipitates
Salt Contamination
In icy conditions, it is common to spread salt on roads and highways, which results in salty runoff that percolates into the unsaturated zone
