SCHRIFTENREIHE Institut für Pflanzenernährung und Bodenkunde ...

Chapter 6 Modeling of Coupled Water and Heat Transfer in Freezing and Thawing Soil
unfrozen soil due to present of ice. Consequently, the upward soil heat flux
becomes higher when the soil gets frozen, and thus it tends to cool the soil
(Smirnova et al. 2000). But the effect of thermal conductivity is probably smaller
than that of water phase change. Consequently, the freezing model, which
considers the both processes, provides a more reasonably and realistic
simulations of soil temperature than the snow routine.
Soil temperature ( o C)
Soil moisture(cm 3 cm -3 )
Soil temperature ( o C)
Soil moisture(cm 3 cm -3 )
Soil temperature ( o C)
Soil moisture(cm 3 cm -3 )
30
20
10
0
-10
-20
a
0.05
0.00
0.10
0.15
0.20
0.25
0.30
0.35
20
10
0
-10
-20
0.20
0.15
0.10
0.05
0.00
20
10
0
-10
-20
0.20
0.15
0.10
0.05
0.00
b
c
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov 26-Dec
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov 26-Dec
M S F Rainfall 40
0
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov26-Dec
Time (days)
20-Mar 25-Mar 31-Mar 5-Apr 11-Apr 16-Apr 21-Apr 27-Apr
M S F
20-Mar 25-Mar 31-Mar 5-Apr 11-Apr 16-Apr 21-Apr 27-Apr
Time (hours)
2 4 6 8 10 12 14 16 18 20 22 24
M S F
2 4 6 8 10 12 14 16 18 20 22 24
Time (hours)
20
Rainfall (mm)
Soil temperature ( o C)
Soil moisture(cm 3 cm -3 )
Soil temperature ( o C)
Soil moisture(cm 3 cm -3 )
Soil temperature ( o C)
Soil moisture (cm 3 cm -3 )
30
20
10
0
-10
-20
0.30
0.35
20 cm
0.05
0.00
0.10
0.15
0.20
0.25
30
20
10
0
-10
-20
40 cm
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
30
20
10
0
-10
-20
0.05
0.00
0.10
0.15
0.20
0.25
0.30
0.35
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov 26-Dec
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov 26-Dec
M S F Rainfall 40
0
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov26-Dec
Time (days)
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov 26-Dec
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov 26-Dec
M S F Rainfall 40
0
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov26-Dec
Time (days)
100 cm
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov 26-Dec
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov 26-Dec
0
9-Feb 21-Mar 30-Apr 9-Jun 19-Jul 28-Aug 7-Oct 16-Nov26-Dec
Time (days)
20
20
S F Rainfall 40
Fig. 6.5. Measured and simulated soil moisture and temperature at 5 cm (a, b, c), 20, 40,
and 100 cm depth in WG during the whole year of 2006 (M: Measured liquid water
content; S: Simulated total water content running snow routine; and F: Simulated liquid
water content running freezing model).
Hydrological Effect of Frozen Soil
The temperature threshold at which precipitation is considered to fall as snow
is specified as -2°C in the model, suggesting that precipitation in winter is falling
20
Rainfall (mm)
Rainfall (mm)
Rainfall (mm)
129