Name ________________________ Geology 127
Test #1 Fall, 1998
Directions: Answer all questions. Put a box around your final answer. I will give partial credit
for answers that use the correct method or set up the problem correctly. To receive partial credit
you must list the proper equation or draw a picture of the problem. Some questions have several
parts, so if you get stuck make an assumption and move on to the next part. Identify all
assumptions clearly.
1) A coastal city has two production wells that are screened in the same unconfined interval.
Well “P1” is located farthest inland, and has a measured water level of 32.13 ft below ground
surface (BGS). This well has a LSE of 93.20 ft ASL and a total well depth of 91.08 ft. Your
quarterly sampling team found that this well contained fresh water at a temperature of 14°C.
Well “P2” is located 1352 ft closer to the ocean, and has a measured water level of 27.37
ft BGS. This well contains salt water with a density of 1040 kg/m3 at a temperature of 14° C.
For reference, the density of pure water at 14° C is 999.244 kg/m3. Well P2 has a total depth of
83.06 ft and a LSE of 88.14 ft ASL.
Part A) What is the total hydraulic head in well P1? (10 points)
Part B) What is the equivalent fresh water head in well P2? (15 points)
Part C) What is the horizontal gradient between well P1 and well P2? (5 points)
Part D) Which way will water flow, and how will this affect the water quality in well P1? (5
points).
2) The intrinsic permeability of a fractured limestone is 5.4 x 10-1 darcy. What is the
corresponding hydraulic conductivity if the fluid temperature is 17° C? Note that the density of
pure water at 17°C is 0.998774 g/cm3, the viscosity of pure water at 17° C is 0.010828 g/s-cm,
and 1 darcy = 9.87 x 10-9 cm2. Express your answer in cm/s (20 points).
3) Briefly discuss the factors that add uncertainty to flood frequency predictions (15 points).
4) Label the three evapotranspiration or precipitation curves on the following diagram from
Fetter (Fig.2.2, p. 33). Shade (label) the areas where there is surplus soil moisture (10 points).
5) A basin has a drainage area of 230 mi2. Use the following storm hydrograph from Fetter, p.
74 to separate baseflow from the overland flow component. Label each area on the graph, and
show all calculations (15 points).
6) What is the difference between specific retention and specific yield? What are the units for
each (5 points)?
