Earth Sciences 340a Physical Hydrology
Laboratory #7 October 25 & 26, 2001
Due November 8 & 9, 2001
Ground Water
Information required to complete this lab can be found in (i) lecture notes (ii) Chapter 6 Hornberger
(iii) Appendix 2 Hornberger.
1. A constant-head permeameter (similar to a “Darcy” apparatus) has a cross-sectional area of 225 cm 2 . The sample is 25 cm long. At a head of 15 cm, the permeameter discharges 50 cm 3 of water
1 in 456 s.
(a) What is the hydraulic conductivity in cm/s, m/s, and m/d?
(b) If the hydraulic conductivity was measured at 20

C, what is the intrinsic permeability? (see
Appendix 2 in Hornberger for water properties)
(c) Using the intrinsic permeability calculated in part (b), calculate the hydraulic conductivity at
5

C, and 30

C. Over this temperature range, which exerts the greatest influence on the hydraulic conductivity; density or viscosity?
2. Calculate the specific discharge in m/s for a hydraulic conductivity of 8.64 cm/d and a hydraulic gradient of 0.019. Is Darcy’s Law valid for this system at 20 
C and N=0.1? Recall
K
 k
 g

and k

Nd
2
3. Calculate the actual velocity in m/s for the information given in question 2 for an effective porosity of 0.1 and 0.0001.
4. In the following diagram, assume a hydraulic gradient of 0.019 with the water level at point A being at an elevation of 300m above sea level. The piezometers are located 500 m apart. Calculate the hydraulic or total head, h
T
, pressure head, h
P
, elevation head, h
Z
, and velocity head:

2
5. The following map shows the ground water elevations in wells screened in an unconfined aquifer at
Milwaukee, Wisconsin. The aquifer is in good hydraulic connection with Lake Michigan. The surface elevation of Lake Michigan is 580 ft above sea level. Lakes and streams are also shown on the map.
(a) Make a water table map with a contour interval of 50 ft. starting at 550 ft.
(b) Draw in ground water flow lines to clearly illustrate ground water flow paths.
(c) What might cause the ground water levels to be below the Lake Michigan surface elevation in part of the area?

6. A piezometer is screened 273.4 m above mean sea level. The pressure head in the piezometer
(often called the point-water pressure head) is 23.4 m and the water in the aquifer is fresh at a temperature of 20

C.
(a) What is the total head in the aquifer at the point where the piezometer is screened?
(b) What is the fluid pressure in the aquifer at the point where the piezometer is screened?
(c) If the aquifer contains brine (not fresh water) with a density of 1400 kg/m
3
, what are the total head and fluid pressure in the aquifer at the point where the piezometer is screened?
7. A piezometer point is 23 m above mean sea level. The fluid pressure in the aquifer at that point is
6.45x10
6
N m
-2
. The aquifer has fresh water at a temperature of 13

C.
(a) What is the point-water pressure head?
(b) What is the total head?
8. A confined aquifer is 24.5 m thick. The potentiometric surface drops by 1.23 m
between two wells that are 1023 m apart. If the hydraulic conductivity of the aquifer
is 44 m/day and the effective porosity is 0.17:
(a) How many cubic metres of flow are moving through the aquifer per unit width?
(b) What is the average linear ground-water velocity?
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