Environmental Engineering Reference
In-Depth Information
represent a seasonal or annual average. Stream
losses are best reported in units of volume of
water loss per unit length of stream per time
(L
2
/T). In this manner, the total amount of loss
from a stream reach can be determined from
knowledge of reach length. Many studies report
streambed infiltration or exfiltration rates as
one-dimensional vertical flux rates (L/T); these
rates are useful for determining hydraulic
conductivity for input to a groundwater flow
model, for example, or for examining the vari-
ability of hydraulic conductivity or flux across a
streambed (Conant,
2004
; Genereux
et al
.,
2008
;
Kennedy
et al
.,
2008
). However, one-dimensional
infiltration rates by themselves do not allow for
calculation of total stream loss rates.
Temperature measurements provide other
useful hydrologic information in addition to
allowing direct quantification of recharge
rates. Streambed temperature measurements
offer an economical means for monitoring flow
duration in intermittent streams (Constantz
et al
.,
2001
; Prudic
et al
.,
2003
,
2007
; Blasch
et al
.,
2004
). The presence of water in a stream
channel substantially reduces the magnitude
of diurnal temperature fluctuations in chan-
nel sediments (
Fig ure 8.11
). Streamflow dur-
ation is an important factor in recharge from
intermittent streams (Besbes,
2006
; Dahan
et al
.,
2007
; Niswonger
et al
.,
2008
). Becker
et al
.
(
2004
) formulated a streamflow hydrograph
separation routine based on measured surface
and groundwater temperatures (
Section 4.6.1
).
Cartwright (
1970
) used differences between
measured temperatures at depths of about
160 m with those predicted solely on the basis
of conductive geothermal heat flow to map
recharge and discharge areas within the Illinois
Basin. Measured temperatures were less than
predicted in recharge areas and greater than
predicted in discharge areas. Reiter (
2003
) used
temperature logs in observation wells to deter-
mine the influence of faults on groundwater
flow in the Albuquerque Basin.
