CE 473/573 Groundwater
Fall 2007
Comments on homework 7
39. I solved this problem by assuming steady flow:
Q0
s=
ln
2πT
R
r
,
which can be written as s = mx + B, where x = ln r,
m=−
Q0
,
2πT
and
Q0
ln R.
2πT
I fit a line to s vs. ln r and computed the transmissivity and radius of influence from
m and B. This approach gives T = 678 m/d and R = 188 m. To test for steady state,
one could solve for the properties using the approach for unsteady flow and compare
the answers. One could also check that u < 0.01 or derive a criterion by using scaling
to estimate the ratio of the unsteady term and the flux divergence term in the flow
equation.
B=
40. All groups derived the requested equation properly and computed K.
42. No problems.
45. I matched the plots at (u, W ) = (0.1, 1) and (r 2 /t, s) = (4.2 m2 /s, 1.1m). Then
T = 0.01 m2 /s and S = 9.5 × 10−4 . With the Jacob method I find T = 0.013 m2 /s
and S = 4.4 × 10−4 using all points and T = 0.011 m2 /s and S = 9.3 × 10−4 using
only the points with u < 0.01. The radii of influence computed with the Sichard and
Jacob methods are quite different.