Effects of Land Use Changes on Water Balance
__________________________________
1165
Table 3
. Mean monthly discharge values during the calibrat
ion and validation periods at Galinak and
Joestan Stations
.
Station
Period
Observed (m
3
s
-
1
)
Predicted (m
3
s
-
1
)
Deviation (%)
Joestan
Calibration
7.5
8.7
16.1
Validation
8.1
10.4
27.3
Galinak
Calibration
11.5
11.7
1.2
Validation
12.1
11.4
-5.3
Table 4.
Results of the statistical evaluation of model perf
ormance on the monthly discharge in the
calibration and validation periods at Joestan and G
alinak Stream Gauging Stations.
Gauging
station
Period
MARE
R
2
E
NS
Results
Joestan
Calibration
0.43
0.76
0.75
Acceptable
Validation
0.61
0.83
0.73
Acceptable
Galinak
Calibration
0.33
0.84
0.84
Good
Validation
0.34
0.90
0.89
Good
calibrated by SWAT during the model
calibration period for Galinak Station were
in good agreement. The observed discharge
was equal to 11.5 m
3
s
-1
compared with the
calibrated discharge of 11.7 m
3
s
-1
.
Similarly, for the validation period, the
above values were 12.1 and 11.4 m
3
s
-1
,
respectively. Notably, the comparative
evaluation of the average monthly discharge
values at Joestan Station showed relatively
good fit between the estimates during the
calibration and validation periods. As far as
the calibration period is concerned, the
average monthly observed and predicted
discharges assumed the values of 7.5 and 8.7
m
3
s
-1
, respectively. Similarly for the
validation period, the observed average
monthly discharge was 8.1 m
3
s
-1
, whereas
the predicted value was equal to 10.4 m
3
s
-1
.
Meanwhile, the average deviation of the
predicted discharges at Joestan Station from
the observed ones were 16.1 and 27.3% in
the calibration and validation stages,
respectively (Table 3).
The values of MARE calculated for the
two stations are generally low and close to
zero (Table 4). The
R
2
and
E
NS
coefficient
are two important statistical indicators for
evaluation of the results. In the case of
Joestan Station, the
R
2
values corresponding
to the relationships between the observed
and predicted average monthly discharges
were found to be 0.76 and 0.83 during the
calibration
and
validation
periods,
respectively. However, the corresponding
values for Galinak Station were 0.84 and
0.90. Therefore, all of results in both stations
and both periods (calibration and validation)
for mean monthly flow showed the goodness
fit of the simulation in the study area.
Therefore, in general, SWAT model was
reasonably capable to reproduce mean
monthly discharge in Taleghan area.
Consequently, based on statistical analysis,
the results show: (i) the model can predicate
the runoff accurately; (ii) the model is
suitable and recommended for the study
area.
Runoff Components
The runoff components encompass surface
runoff, lateral flow, and groundwater flow.
According to Linsley
et al.
(1949); Linsley
et al.
(1982), and Klemes (1986), drawing
distinction between the components of
runoff is arbitrary and the source(s) of the
water passing a gauging station cannot be
identified,
therefore,
comparing
the
predicted fluxes against any observation at
the two gauging stations within the Taleghan
basin is not possible. Figures 3 and 4 show
the monthly surface runoff, lateral flow, and
Results (
Arabic) 1:
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آثار التغيرات في استخدام الأراضي على توازن الماء __________________________________ 1165 الجدول 3. يعني شهريا تفريغ القيم خلال كاليبراتفترات أيون والتحقق من الصحة في جاليناك و محطات جوستان. محطة الفترة الملاحظة (m3 s-1) توقع (m3 s-1) الانحراف (%) جويستان معايرة 7.5 8.7 16.1 التحقق من الصحة 8.1 10.4 27.3 جاليناك معايرة 11.5 11.7 1.2 التحقق من الصحة 12.1 11.4 -5.3 الجدول 4. نتائج التقييم الإحصائي للأداء النموذجيأورمانسي على أداء شهري في فترات والمعايرة والتحقق من الصحة في جوستان وزاليناك "محطات قياس تيار". قياس محطة الفترة ماري R2هNSالنتائج جويستان معايرة 0.43 0.76 0.75 مقبولة التحقق من الصحة 0.61 0.83 0.73 مقبولة جاليناك معايرة 0.33 0.84 0.84 جيدة التحقق من الصحة 0.34 0.90 0.89 جيدة معايرة من سوات من خلال النموذج كانت فترة المعايرة لمحطة جاليناك اتفاق جيد. الاضطلاع بالملاحظة وكان يساوي 11.5 متر3 s-1 مقارنة معايرة التفريغ م 11.73 s-1. وبالمثل، لفترة التحقق من الصحة، فوق القيم كانت 12.1 و 11.4 م3 s-1, على التوالي. جدير بالذكر أن المقارنة تقييم أداء شهري متوسط تظهر القيم في محطة جوستان نسبيا جيدة تناسب بين التقديرات خلال فترات والمعايرة والتحقق من الصحة. قدر تشعر فترة المعايرة، في المتوسط شهريا ولاحظ وتوقع discharges assumed the values of 7.5 and 8.7 m3 s-1, respectively. Similarly for the validation period, the observed average monthly discharge was 8.1 m3 s-1, whereas the predicted value was equal to 10.4 m3 s-1. Meanwhile, the average deviation of the predicted discharges at Joestan Station from the observed ones were 16.1 and 27.3% in the calibration and validation stages, respectively (Table 3). The values of MARE calculated for the two stations are generally low and close to zero (Table 4). The R2 and ENS coefficient are two important statistical indicators for evaluation of the results. In the case of Joestan Station, the R2values corresponding to the relationships between the observed and predicted average monthly discharges were found to be 0.76 and 0.83 during the calibration and validation periods, respectively. However, the corresponding values for Galinak Station were 0.84 and 0.90. Therefore, all of results in both stations and both periods (calibration and validation) for mean monthly flow showed the goodness fit of the simulation in the study area. Therefore, in general, SWAT model was reasonably capable to reproduce mean monthly discharge in Taleghan area. Consequently, based on statistical analysis, the results show: (i) the model can predicate the runoff accurately; (ii) the model is suitable and recommended for the study area. Runoff Components The runoff components encompass surface runoff, lateral flow, and groundwater flow. According to Linsley et al. (1949); Linsley et al. (1982), and Klemes (1986), drawing distinction between the components of runoff is arbitrary and the source(s) of the water passing a gauging station cannot be identified, therefore, comparing the predicted fluxes against any observation at the two gauging stations within the Taleghan basin is not possible. Figures 3 and 4 show the monthly surface runoff, lateral flow, and
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