Quiz 3 Part 2
water table
The boundary between the saturated zone and the unsaturated zone.
The pore spaces in the saturated zone are completely full of water; the pore spaces in the unsatrated zone are not completely full of water.
The difference between the saturated and unsaturated zones of groundwater.
recharge
The infiltration of water into the subsurface.
cone of depression
The lowering of the water table near a well.
discharge
The volume of water flowing past a given point in a given time.
floods
The volume of water flowing past a given point in a given time.
Which of the following statments about the water table is false?
The water table is generally flat
For a given river, which of the following floods would have the largest discharge?
a 100-year flood
How fast does most groundwater move in aquifers?
a few centimeters per day
Groundwater represents how much of the world's fresh water?
about 20%
If a dam is built, sediment will ___________ on the upstream side of the dam and sediment will ____________ on the downstream side of the dam.
accumulate... erode
California imports most of its water supply. What is most (>80%) of the water used for?
agriculture
Which of the folowing rocks has the highest permeability?
an uncemented sandstone
Which of the following equations is correct for discharge?
discharge = width x depth x velocity
At a bend in a river, ___________ occurs on the outside of the bend and __________ occurs on the inside of the bend.
erosion... deposition
Natural levees are built up by _____________.
floods
Which of the following materials has the lowest porosity?
granite
Which of the following reservoirs contain the most available fresh water on Earth?
groundwater
Which of the following combinations make for the best groundwater reservoir?
high permeability and high porosity
What is the process by which water enters the small pore spaces between particles of soil or rock?
infiltration
Most groundwater withdrawn in the United Sates is used for _______________.
irrigation
How much of the Earth's total water is stored in underground aquifers?
less than 1%
What is the name for a curved sandbar that forms on the inside curve of a stream?
point bar
The percentage of a rock's total volume taken up by pore space is called the ___________.
porosity
A confined aquifer is recharged by __________________.
precipitation where the aquifer crops out
Which of the following is not caused by overpumping groundwater?
raising of the land surface
Natural levees are made up of ______________.
sand and gravel deposited during a flood
Permeability is ______________.
the ability of a solid to allow fluids to pass through
The east coast of North America lacks deltas because __________________.
waves and tides are too strong
Why is the Mississippi delta so large?
-Because the Mississippi River transports a huge amount of sediment -Because tides in the Gulf of Mexico are not very strong -Because waves in teh Gulf of Mexico are not very strong
Excessive pumping in relation to recharge can cause ____________.
-the water table to decline -a cone of depression to form -the well to go dry
What is the probablity of a 50-year flood occurring next year?
2%
aquiclude
A relatively impermeable geologic unit?
What is the primary reason sediment is deposited in large cone-shaped deposits at mountain fronts?
Because stream valleys widen abruptly at a mountain front.
Which of the following statements regarding floods is true?
If there is a 20% probablity of a flood of a certain height occurring in any one year, it is a 5-year flood
