Evaluation of the Impacts of Climate Change on Runoff in Dadu River
Basin Based on CORDEX Regional Climate Model
Abstract
Owing to the rich water resources, the Dadu River basin is an important
hydroelectric resources development area in Sichuan Province over China.
The climate change will have a great impact on the runoff change in the
Dadu River Basin. The prediction of the future runoff in the Dadu River
Basin can effectively improve the utilization rate of water resources,
and provide a reference for hydropower dispatching. At first, to reduce
the uncertainties from climate model, this paper used Stepwise
Clustering Analysis to calibrate and validate the CORDEX regional
climate model ensemble data from 1970 to 2005 and projected the climate
change trend of Dadu River basin from 2035 to 2065. Then the Dadu River
watershed scales of SWAT model was established, using the SWAT-CUP for
calibration and verification. Finally, the corrected future climate data
are used to drive the SWAT model to realize the future runoff forecast
in the Dadu River Basin. The results show that under the scenario of
RCP4.5 and RCP8.5, the variation range of rainfall is small, and the
maximum and minimum temperatures show an overall increasing trend. The
maximum (minimum) temperature will increase about 0.6℃ (1.0℃) under the
scenarios of RCP4.5 and 0.9℃ (1.4℃) under the scenario of RCP8.5.
Compared with the baseline period, the future (2035-2065) annual runoff
under RCP4.5 and RCP8.5 scenarios will increase by about 8.6% and
8.2%, respectively. Under the future climate change, the inter-annual
runoff in the Dadu River Basin will change greatly, and the trend of
runoff fluctuation is not consistent before and after 2050. Before 2050,
runoff changes are small, however, after 2050, runoff changes under the
two scenarios will increase by about 12%. On the one hand, this trend
may be due to the impact of iceberg melting on runoff caused by
temperature changes around 2050, on the other hand, it may be due to the
combined effect of local plant evapotranspiration and ecological
regulation.