temperature are higher than the upper stream of the groundwater flow. Groundwater
velocity is measured by the relationships between the groundwater flow velocity and
temperature difference of the upper stream and downstream as shown in Eq. (19.11)
and Eq. (19.12).
In the region of the flow velocity, 2 Â 10
À6
V d 10
À4 m/s
V d ¼ T dev =61:33
½
Š
1:16
ð19:11Þ
In the region of flow velocity, V d > 10
À4 m/s
V d ¼ ΔT=0:053
½
Š
À1:19
ð19:12Þ
where V d ¼ Darcy’s flow velocity, T dev ¼ standard deviation of the average
temperature uprising, ΔT ¼ average temperature uprising (JGS 2016).
Table 19.4 Groundwater velocity measurement methods (JGS1318-2015, Yamamoto et al. 2017)
Method
Tracer
Principle of
measurement
Dimension
(error)
Velocity
range (m/s) Ref
Electric potential difference
measuring
method
Diluted water
or different
specific conductivity of
water
Measuring specific conductivity around the
injected tracer
Horizontal
2D (Æ7.5
)
10
0 - 10
À7
JGS (2016)
Temperature
measurement
method (heat
flow type)
Heat
Measuring
water temperature around the
heater
8 sensor
type: Horizontal
2D
(Æ22.5
)
10
À2
–10
À7
16 sensor
type: Horizontal
2D (Æ10
)
1.7 Â 10
À4
À1.7 Â 10
À6
Particle tracking
method
Particle in
water
Tracing special
particles by the
video
microscope
3D
(no data)
10
À3
–10
À6
Measuring
Doppler effect
using ultrasonic
3D
(Æ12.5
)
10
À5
–10
À9
Paper disk type
groundwater
velocimetry
Dye ink
Measuring tailing of the dye
ink eluted from
the printed dot
on the paper
Horizontal
2D
(Æ22.5
)
1.7 Â 10
À4
–
1.7 Â 10
À6
Yamamoto
et al. (2017),
Ono et al.
(2016)
556
H. Takahashi et al.