differences were presented in summer. On the contrary, the surface runoff increased
about 39 mm, 35 mm and 23 mm for the years of 2003, 2004 and 2005 under the
conversion of FGA into urbanization.
2.4 Discussion
2.4.1 Model Uncertainty
Model uncertainties are resulted from uncertainties in input data, model dynamics
and physics and parameter values. To reduce uncertainties of the HYPE model and
examine the suitability of HYPE for impact studies in the KRB, the model was
calibrated and validated at the gauge of the basin outlet. The calibration and
validation results showed that HYPE simulations matched observations well in
various periods. Although this ensures that HYPE is applicable in this basin, it is
recognized that HYPE displayed relatively large biases in terms of base flows that
were most likely due to lack of soil hydrology data (field capacity, wilting point,
etc.). These biases, however, should not compromise our analysis results since the
analysis was based on the comparison of different simulated scenarios and was not
focused on base flow.
0
10
20
30
40
50
60
70
80
90
1/1/2003
6/30/2003
12/27/2003
6/24/2004
12/21/2004
6/19/2005
12/16/2005
Discharge (m 3
/s)
Time
S4
S3
Fig. 2.5 Simulated daily stream flows at KRB outlet according to S3 and S4
2 Modeling the Effects of Land Use Change and Climate Change on Stream Flow. . .
29