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Hydrogeologic Framework and Simulation of Ground-Water Flow and Travel Time in the Shallow Aquifer System in the Area of Naval Support Activity Memphis, Millington, Tennessee 

 
 
Table 7. Input parameters for the calibrated flow model of the shallow aquifer system in the area of Naval Support Activity Memphis, Millington, Tennessee
[in/yr, inches per year] 
Parameter
Model  Layer
Adjusted Value
Source
Natural recharge (in/yr)
0.32
Estimated during model calibration with parameter-estimation program.
Anthropogenic recharge (in/yr)
0.67 - 1.8
Estimated during model calibration with parameter-estimation program.
Altitude of starting heads in feet
Layer 3
184 - 229
Estimated using September 1995 potentiometric map of Memphis aquifer (Kingsbury, 1996).
Transmissivity, in feet squared per day
Layer 1:
Southwest of 
erosional scarp 
53 - 371
Estimated using horizontal hydraulic conductivity of alluvial-fluvial deposits aquifer determined
by August 1995 aquifer test and thickness of alluvial-fluvial deposits. 
Northeast of 
erosional scarp
53 - 265
Estimated using horizontal hydraulic conductivity of upper sand units of Cockfield Formation determined by specific-capacity tests and thickness of those units in stratigraphic test holes.
Area of erosional 
scarp
2
Estimated during model calibration.
Layer 2
28 - 300
Estimated during model calibration with parameter-estimation program.
Layer 3
not applicable
The transmissivity is irrelevant because layer 3 is a specified head boundary.
Vertical conductance between layers in feet per day per foot
Layer 1:
Buried river valleys
4 x 10-4
Estimated during model calibration.
Fault
4.9 x 10-5
Estimated during model calibration with parameter-estimation program.
Elsewhere
1 x 10-7
Calculated using vertical hydraulic conductivity of sediment cores and unit thickness with equation 53 (McDonald and Harbaugh, 1988).
Layer 2: Fault 
4.9 x 10-4 to
4.9 x 10-3
Estimated during model calibration with parameter-estimation program.
Window in 
confining unit
8.8 x 10-5
Estimated during model calibration with parameter-estimation program.
Elsewhere
1 x 10-6
Calculated using vertical hydraulic conductivity of sediment cores and unit thickness with equation 53 (McDonald and Harbaugh, 1988).


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