Environmental Engineering Reference
In-Depth Information
Table 9.2.
Space scales, relative expense, and complexity of application of individual methods for estimating
groundwater recharge. Space scales are given as areas, with the exception of the stream water-budget method
for which the scale refers to the length of stream channel over which measurements are integrated. Expense
and complexity are ranked on a scale of 1 (lowest) to 5 (highest). Additional details are discussed in the text.
UZ is unsaturated zone. WB is water budget. GW is groundwater. WS is watershed. SW is surface water. HS is
hydrograph separation. CFC is chlorofluorocarbons. SF
6
is sulfur hexafluoride.
Space scales
Relative
expense
Relative
complexity
1
m
2
10
m
2
100
m
2
1
ha
1
km
2
10
3
km
2
10
6
km
2
Chapter
Water budget
aquifer
2
x
x
x
x
2 to 4
2 to 4
soil column
2
x
3
3
watershed
2
x
x
x
x
2 to 4
2 to 4
stream
4
x
x
x
5
4
Models
UZ soil WB
3
x
2
2
UZ
3
x
x
x
x
4
4
Richards
equation
watershed
3
x
x
x
x
2 to 5
5
GW flow
3
x
x
x
x
2 to 5
5
combined
3
x
x
4 to 5
5
WS/GW
empirical
3
x
x
x
x
x
x
x
1
1
Darcy methods
UZ
5
x
x
5
5
UZ unit
5
x
x
3
3
gradient
GW
6
x
x
x
2
2
SW/GW
4
x
x
x
3
3
UZ/GW methods
zero-flux
5
x
x
5
4
plane
lysimeter
5
x
x
x
1 to 5
1 to 5
water-table
6
x
x
2
2
fluctua-
tion
Surface water based
seepage
4
x
2
2
meter
step-
4
x
x
x
x
3
3
response
function
flow
4
x
x
x
1
1
duration
hydrograph
4
x
x
2
3
separa-
tion (HS)
