Climate Change and Its Impacts on Streamflow: WRF and SCE-Optimized SWAT Models - Data Assimilation for Atmospheric, Oceanic and Hydrologic Applications - page 417

Fig. 17.9 Future stream flow (compared to baseline stream flow) ( left ) Kontum observed station—
Dakbla river basin) ( right ) Trung Nghia observed station—Poko river basin

increase in steamflow of about 48 % than Poko river basin that shows about 10 %
increase during the peak rainfall season. During the dry season, about 15 % decrease
is seen over both Dakbla and Poko basins.

17.4 Conclusions

Existing research studies indicate uncertainties in climate projections stemming
from global climate models and different emission scenarios of climate change.
Since global climate output have been found insufficient for regional and local
impacts, it has been realized that adaptation measures to combat climate change
requires high spatial resolution information and hence the use of regional climate
models in climate research has become common. Since hydrology is one of the most
common impact studies, this chapter highlights the importance of high resolution
models in impacts research and the use of sophisticated optimization algorithms
when applying hydrological models.
Rainfall derived from climate model has been applied to a hydrological model
(SWAT) which was calibrated with SCE-UA algorithm and its simulated discharges
were compared with the their observed counterparts. The performance of the
model using station data rainfall has been found satisfactory and hence the model
derived rainfall were also used to see assess stream flow simulation over the
current and future climate. Using the RCM driven by GCM ECHAM5, the present-
day and future stream flows were also simulated. Results show that, both over
Dakbla and Poko river basins, the future stream flow is expected to increase,
especially during the peak rainfall season. The Dakbla river basin shows a more
pronounced increase than the Poko river basin.
However, further work is required to improve the confidence in these results. As
mentioned before, a higher resolution simulation of the RCM may be required to
obtain more credible estimates of future precipitation. In addition, since this result
has been obtained only from one run of the RCM, it is recommended to obtain an