Chapter 9: Ground Water
Which three statements below are correct?
-Groundwater typically flows at a rate of only a few centimeters each day. -Groundwater flows under the force of gravity. -Groundwater flows from regions where the water table is high to regions where the water table is low.
Where in the world has groundwater withdrawal resulted in subsidence problems?
-New Orleans, LA -San Joaquin Valley,CA -Houston-Galveston, TX -Mexico City, MEX
Which three statements below are correct regarding caverns?
-Stalagmites and stalactites are both considered speleothems. -The cavern was formed below the water table as groundwater dissolved away the rock. -The dripstone formations occurred in the unsaturated zone above the water table sometime after the water table lowered.
This image is showing a cone of depression. Which two statements below are correct regarding this image?
-The cone of depression is caused from water being pumped from the well. -The size of the cone of depression is related to how fast groundwater is pumped from the well.
The High Plains (Ogallala) Aquifer is:
-a major aquifer running from the panhandle of Texas to southern South Dakota. -being depleted in the Texas Panhandle. -being depleted in southwestern Kansas. -being depleted in the Oklahoma Panhandle
Perched water tables:
-generally form above an aquitard. -are the upper limit of a localized zone of saturation
Karst topography:
-generally has many sinkholes. -generally has disappearing streams. -may contain erosional remnants know as karst towers. -most often forms in areas where the water table is high and the rock is limestone.
Porosity is the storage capacity in rocks. Which three factors below would tend to increase the porosity?
-highly fractured rock -well sorted grains (all about the same size) -larger size grains
These pie charts reveal:
-in the United States we use more surface water than groundwater. -groundwater supplies approximately 24% of all fresh water use in the U.S. -Most groundwater is used in irrigation. -some groundwater is used in mining.
The water table:
-is the upper limit of the zone of saturation. -is generally a subdued replica of the surface topography. -can fluctuate with seasonal changes such as drought. -is represented by the black dashed line.
Wells are the most common means by which people obtain groundwater. For a water well to be productive:
-it must be drilled into an aquifer. -it must be drilled below the water table. -it must be drilled into permeable rock or sediment.
Which four below are possible sources of groundwater contamination?
-sewage from septic tanks -landfills where trash is dumped -agricultural chemicals (pesticides and fertilizers) sprayed on crops -leaking motor oil from automobiles
The signs on the pole that read "1925" and "1955" are where the land elevation was in those years. This image is showing:
-that groundwater withdrawal has caused subsidence of the land. -the result from compacting sediments created by groundwater withdrawal.
This photo is of a flowing artesian well. For a flowing artesian well to exist:
-the pressure surface must be higher than ground level. -the aquifer must be confined by aquitards above and below. -the aquifer must be inclined. -the aquifer must be recharged in an area of higher elevation.
400 ml of water was added to 1,000 cm3 of dry sand before it became saturated. What is the porosity of the sand? (1 ml = 1 cm3 )
40%
This photo is of Old Faithful, a famous geyser in ________ National Park.
Yellowstone
Which rock below would tend to be the best aquifer?
a poorly-cemented, well-sorted sandstone
Fresh water is a very precious resource and should be used sparingly. According to this graph, how many gallons of fresh water are used per capita (total water use / number of people) in the U.S. daily?
around 70
Since glacial ice is not readily available for human use, the only fresh water available is either groundwater (30.8% of all fresh water) , and water in lakes and rivers at only 0.3% of all fresh water. So what percentage of all readily available fresh water is found in the ground?
around 99%
An aquitard has very low permeability. Which type of material listed below would tend to be an aquitard?
clay (shale)
Which situation below is most common?
gaining stream
Natural springs:
occur whenever the water table intersects the earth's surface.
For most igneous and metamorphic rocks to have good porosity and permeability, it generally requires:
that the rocks are highly fractured.
This photo is of Mammoth Hot Springs in Yellowstone National Park. The terraces in the photo form from chemical precipitation of dissolved mineral matter in the spring water. The mineral precipitating out is calcite, and the rock forming the terraces is called:
travertine
The majority of hot springs in the United States are located in the:
west
