Numerical Analysis of Water Movement in Agricultural Fields …
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significantly varies with soil type. It shrinks from around 2.5 m from the surface in
homogeneous medium (Fig. 1b) to around 2 m in the highly heterogeneous media
(Fig. 1f). The soil moisture variability range also depends on the media type, and
it decreases with increasing soil heterogeneity. Near to the surface, for example,
it varies between 14–19% and 15–17% on homogenous and highly heterogeneous
soils, respectively. Unlike in the cases where water uptake was ignored, the minimum
mean soil moisture was observed near to the surface when root water uptake was
accounted. Under homogeneous and highly heterogeneous soils, the response of soil
moisture change was fast for the applied water (Fig. 1b, f). But, it was delayed for
the moderately heterogeneous soil (Fig. 1d). When there was no root water uptake,
the maximum soil moisture content was observed on the second day after irrigation
for all soil types, and the peak value was observed on the moderately heterogeneous
soil (Fig. 1c).
3.2 Effect of Root Water Uptake and Soil Heterogeneity
on Suction Head
Mean suction head distribution when there was no crop cover exhibits small range of
negative head. As shown in Fig. 2a, c, and e, the matric head profile shows decrement
in head (became less negative) with increasing soil heterogeneity simulated under
the same initial conditions. A significant change in suction head was observed when
root water uptake was considered. Under homogeneous soil condition, the minimum
head range dropped from −4.5 to −27 m (Fig. 2a, b). From Fig. 2, it is possible
to see a shift in the location where the minimum suction head took place as root
water uptake was accounted. When it was ignored, the minimum head was observed
at 0.5 m depth from the surface irrespective of heterogeneity. But, it was shifted to
around the surface when root water uptake was considered. In addition, a smooth
shift in head profile was exhibited from day 1 to day 6 in no uptake scenarios. A
sudden rise and maximum value in head was observed on the day of irrigation in
cropped surfaces. The maximum head achieved under irrigation condition varies
with soil heterogeneity. For example, for homogeneous case, the maximum head
recorded was −4 m, and it was −6 and −9 m on moderately heterogeneous and
highly heterogeneous cases, respectively, when root water uptake was considered.
The range where root water uptake effect was observed depends on soil heterogeneity.
3.3 Effect of Root Water Uptake and Soil Heterogeneity
on Hydraulic Conductivity
Hydraulic conductivity increases with increasing heterogeneity of soil when root
water uptake was not considered, and its maximum value was observed near to
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significantly varies with soil type. It shrinks from around 2.5 m from the surface in
homogeneous medium (Fig. 1b) to around 2 m in the highly heterogeneous media
(Fig. 1f). The soil moisture variability range also depends on the media type, and
it decreases with increasing soil heterogeneity. Near to the surface, for example,
it varies between 14–19% and 15–17% on homogenous and highly heterogeneous
soils, respectively. Unlike in the cases where water uptake was ignored, the minimum
mean soil moisture was observed near to the surface when root water uptake was
accounted. Under homogeneous and highly heterogeneous soils, the response of soil
moisture change was fast for the applied water (Fig. 1b, f). But, it was delayed for
the moderately heterogeneous soil (Fig. 1d). When there was no root water uptake,
the maximum soil moisture content was observed on the second day after irrigation
for all soil types, and the peak value was observed on the moderately heterogeneous
soil (Fig. 1c).
3.2 Effect of Root Water Uptake and Soil Heterogeneity
on Suction Head
Mean suction head distribution when there was no crop cover exhibits small range of
negative head. As shown in Fig. 2a, c, and e, the matric head profile shows decrement
in head (became less negative) with increasing soil heterogeneity simulated under
the same initial conditions. A significant change in suction head was observed when
root water uptake was considered. Under homogeneous soil condition, the minimum
head range dropped from −4.5 to −27 m (Fig. 2a, b). From Fig. 2, it is possible
to see a shift in the location where the minimum suction head took place as root
water uptake was accounted. When it was ignored, the minimum head was observed
at 0.5 m depth from the surface irrespective of heterogeneity. But, it was shifted to
around the surface when root water uptake was considered. In addition, a smooth
shift in head profile was exhibited from day 1 to day 6 in no uptake scenarios. A
sudden rise and maximum value in head was observed on the day of irrigation in
cropped surfaces. The maximum head achieved under irrigation condition varies
with soil heterogeneity. For example, for homogeneous case, the maximum head
recorded was −4 m, and it was −6 and −9 m on moderately heterogeneous and
highly heterogeneous cases, respectively, when root water uptake was considered.
The range where root water uptake effect was observed depends on soil heterogeneity.
3.3 Effect of Root Water Uptake and Soil Heterogeneity
on Hydraulic Conductivity
Hydraulic conductivity increases with increasing heterogeneity of soil when root
water uptake was not considered, and its maximum value was observed near to