GEO 440 Study Guide - Final Guide: Surface Runoff, Phreatic Zone, Baseflow
Fall 2013 Geohydrology Review Sheet for Midterm Exam
1. In the first week of class you looked over a newspaper article titled "Antrim Water
Supply Threatened" Why is it thought that the levels of contamination in the municipal
water supply (from the Cedar River) might rise in the next 10 years?
● Levels may rise in the next ten years because that is when the higher plume may reach
the well. Lower concentrations of contamination are located on the edges of the plume,
and higher concentrations of contamination are located towards the inner/middle of the
plume. Groundwater moves slowly, but the lower leading plume is more likely to move
before the higher plume.
Hydrologic Cycle
● The circulation of water from the atmosphere to the earth and its return to the
atmosphere through transpiration and evaporation.
● This system is not really a steady state system. A change in one part of the cycle affects
the other connected parts of the cycle. You cannot call your whole system a steady
state system because you have a variable that is changing.
● Instead you call these variables transient.
● https://www.ec.gc.ca/eau-water/default.asp?lang=En&n=23CEC266-1 nice Canadian
website that helps explain it.
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Soil Moisture
● A key variable in controlling the exchange of water and heat energy between the land
surface and the atmosphere through evaporation and plant transpiration.
Vadose Zone (unsaturated zone)
● Part of the Earth between the land surface and the top of the phreatic zone (groundwater
zone).
● The position in which groundwater is at atmospheric pressure.
Water Table
● The level below which the ground is saturated with water.
Tracer Test
● Inject a known mass or concentration into the groundwater and install wells throughout
the area to measure the concentration at each well. (elaborate).
Infiltration
● The amount of water (rain) that can infiltrate into the soil or ground.
● This depends on factors such as rainfall intensity and amount, soil permeability (different
soil types), surface slope, etc.
● Some percentage of infiltration could become groundwater.
Infiltration Capacity (rate)
● The maximum rate at which water can be absorbed by a given soil per unit area under
given conditions
Runoff
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● The draining away of water (or substances carried in it) from the surface of an area
of land.
Depression storage
● The ability of a particular area of land to retain water in its pits and depressions thus
preventing it from flowing.
Transpiration
● Transfer of water to the atmosphere by vegetation
Evapotranspiration
● Usually we just combine evap and trans together
● In arid Arizona, a vegetation change from deep rooted Chaparral to shallow rooted
grasses caused an increase in streamflow of several hundred percent
1. What is the largest source of non frozen freshwater?
● Largest source of non frozen freshwater is groundwater.
2. What is most groundwater pumped out of the ground in the United States used for?
● Most of the groundwater is used for irrigation or agriculture.
3. About how many times more groundwater is there compared to water in rivers,
streams and lakes?
● There is 113 times more groundwater than surface water.
4. Jim Bob has carefully measured water levels in all the wells at a site and he bragged to
his boss that she could go out two weeks later, re-check his measurements and would
get the same answers as he did. If Jim Bob's boss went out and checked, what would
she find? Would the water levels be the same, even if it had not rained in those two
weeks?
5. What happened during the University of Waterloo tracer test? What went wrong and
what was their mistake?
● They measured which way groundwater was flowing in the spring and then had students
install wells. The next year they conducted a tracer test towards the end of summer and
only a few of the wells indicated where the tracer was.
● Groundwater flow changes depending on the time of year. For instance they measured
which direction groundwater was flowing in the spring, but conducted the test in late
summer (August). Therefore the groundwater flow direction had changed.
6. Would you expect a vegetation change in Arizona from deep rooted chaparel to
shallow rooted grasses to effect streamflow in adjacent streams? If so, how would it
effect streamflow (increase or decrease?) Assume that watering of the grasses did not
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find more resources at oneclass.com
