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touches soil and the decreasing of SWD. Therefore, ∆
De
was from the sec-
ond layer (0.789 mm/day) always higher than topsoil (0.483 mm/day). In
case of H-13, the rainfall water suppressed the SWD upward from top layer
around mid night and the SWD from the second layer to become hamper-
ing. The water rainfall depresses not effective for the third layer. Due to
the ∆
θ
still negative, ∆
De
from the second layer
<
the third layer, ∆
De
profiles are same with case S-12. By applying of H-23 pattern shows a con-
sistency of soil water availability impact to reduce
De
upward when the
rainfall appeared. Because the ∆
θ
in topsoil is positive, the water rainfall
fills pore soil more deeply, and then
De
from the second layer was affected.
3.2.
Water depletion pursue with heavy rainfall
In case of November 8, 2003 when the heavy rainfall occurs in the night
(28.4 mm) in case of all ∆
θ
patterns, the water percolate and reach
the fourth layer as downward SWD and dominate ∆
De
into deep layer
(Fig. 2(b)). By using the initial SWD are as S-13, S-23, and S-03, the
amplitude of ∆
De
profiles on wet season was similar. It was around
5.955 mm/day, and the level of
De
is not in order, where it was in the first
layer
>
the second layer, and then the second layer
<
the third layer
<
the
fourth layer.
4. Conclusion
There are eight possibility of ∆
θ
fluctuation patterns in three soil profiles
which it range from dry (H-03) to wet (S-03) condition. By applying those
patters as initial SWD into model found that, the first layer SWD is always
exist and higher than others layer, except for H-03 followed on by cloudy
day with minimum threshold rainfall is around 0.6 mm/day, and H-13 and
S-23 pattern for extreme rainfall. The total of ∆
De
is more elevated when
the positive ∆
θ
is predominant. The SWD in the day without rain is dom-
inated by water losses upward and opposite in the day particularly with
extreme rain.
Acknowledgments
The climatologically data was provided from Dr. Hiroyuki Hashiguchi
from Radio Science Center for Space and Atmosphere, Kyoto Univer-
sity, Kyoto, Japan. This study is also supported by IORGC JAMSTEC,
Japan.
