The impact of urban groundwater upon surface water - eTheses ...

Material
Thickness
m (b)
Horizontal
Conductivity
md -1 (Kx)
GROUNDWATER FLOW MODELLING
Vertical
Conductivity
md -1 (Kz)
Sandstone 90.25 2 0.2
Weathered Sandstone 2 3 1
Gravels 3.95 5 0.5
Total Depth 96.2 - -
KxAverage
KzAverage
=
n
Knbn
1 b
∑
= n
∑
1
b
bn
Kn
- 2.14 -
- - 0.209
Transmissivity m 2 d -1 - 206.25 -
Table 6.3 Average conductivity for the saturated thickness of the FAT3D steady state
model.
MODFLOW model reach and that the calibration target used for the FAT3D model of a
minimum groundwater discharge of 2 m 3 d -1 is probably too low. MODFLOW results indicate
that some of the highest groundwater discharges to the river occur in the vicinity of Profile 8
with flow rates of 4 to 5 m 3 d -1 (Section 6.8). Values of transmissivity and conductivity
derived from the FAT3D model should be regarded as minimum values.
The results of the MODFLOW model show that the riverbed poses no significant impedance
to groundwater flow until the riverbed conductance term (length*width*K)/(thickness of the
riverbed sediments) drops below 100 m 2 d -1 which equates to an approximate conductivity of
0.6 md -1 . The FAT3D steady state model achieved calibration with a riverbed Kz conductivity
188