Lecture 9 Flashcards
Define a water table
The line of complete saturation above the groundwater. This is a dynamic and changing boundary
Define through flow.
Horizontal flow of water within the soul matrix above the water table. This happens when soil becomes saturated and the water moves due to gravity towards a stream or lake
Define groundwater flow.
Underground topographic flow of groundwater due to gravity.
Define percolation
Vertical movement of water downward through a soil matrix
True or False:
The ground water zone is totally saturated
True
True or False:
Ground water supplies lakes and rivers but not oceans.
False. It supplies all three
Do larger or smaller sediments promote quicker groundwater flow?
Smaller
What is unconfined groundwater?
Groundwater not restricted by an impervious layer of rock
Define a perched water table.
A water table present above another water table due to an impervious rock layer
What happens to confined groundwater.
It becomes pressurized
True or False:
An artesian well occurs when pressurized confined groundwater reaches the surface
True
What recharges groundwater?
Precipitation percolating down
True or False:
Groundwater has a short residence time
False
What can intercept precipitation in its way to groundwater?
Vegetation absorbing water from the ground or catching it in the canopy
What is infiltration?
Water entering a soil matrix
What is the difference between the zone of aeration and the water table?
The water table is complete saturation and the zone of aeration is only partially saturated
Name three methods of water energy movement.
Hydroscopic, capillary, gravitational
Define hydroscopic movement of water.
Microscopic particle adhesion. Very small scale
Define the capillary movement of water.
Held in the pour matrix
Define the gravitational flow of water
Water flowing readily through large spaces
What is the order of strength in the methods of water movement
Hydroscopic > capillary > gravitational
What three things will increase the permeability of soil?
Add gravel under
Sand on the top
Aerate
What is porosity?
% volume pore space in a rock or sediment. It is a measure of holding capacity
Does clay have a low or high water retention? Why?
High. Because of the larger surface area. Clay is platelets of minerals and lots of water can adhere to this
Define hydraulic conductivity.
Ability of water to flow.
Define permeability.
The ability of a substrate to transmit water, requires the water to be connected and varies with pore size.
Define and aquitard.
A surface not permeable to water
Define and aquifer
A substance containing water
What makes a well flow?
There must be surface pressure
What three things control groundwater movement
Substrate: porosity and permeability
Pressure: a function of the weight of the water at a depth
Elevation: potential energy above sea level
True or False:
Groundwater flows low to high pressure
False
Where does water flow when the water table is high?
Down
True or false:
Water will flow up towards a low discharge area
True
What is hydraulic head?
A function of pressure and elevation that is a length term.
What causes a cone of depression?
A well inserted into ground water that drains the surrounding groundwater
What is Groundwater?
Water that occupies space in the pores of sediment or rock below the earths surface
