Response of Hydrologic Processes to Future Climate Changes in the Yangtze River Basin

AbstractRecent climate changes have observable impacts on hydrologic processes and will further affect hydrologic systems in the future. The temperature and precipitation modeled with eight global circulation models (GCMs) (selected from 22 GCMs published in the Fourth Assessment of the Intergovernmental Panel on Climate Change) under three typical emission scenarios entitled A1B, A2, and B1 were evaluated in this study for future projections in the Yangtze River Basin, China. The artificial neural network model was used to assess the evolutional trend of hydrologic processes (e.g., streamflow) and the possibility of extreme floods in the Yangtze River Basin by using data generated by selected GCMs under future climate changes. The results indicate that the future annual streamflow tends to decrease in the Yangtze River Basin. The future average annual flow is reduced by 500 m3/s compared with that of the historic record (1951–2005) observed at Yichang Hydrologic Station of the Middle Yangtze River, and the percentage of dry years increases by 46.8%. However, at Datong Hydrologic Station of the Lower Yangtze River, the average annual flow is reduced by 210 m3/s compared to the historic record and the percentage of normal year increases up to 75.5%. Extreme floods are divided into three categories of catastrophic, great, and large floods. The results show that large floods are most likely to occur in the future, whereas the likelihood of extreme floods is the minimum under the B1 scenario. In the three decades of the 2020s, 2050s, and 2080s, the likelihood of extreme floods at Yichang and Datong Hydrologic Stations tends to increase; the likelihood of extreme floods at Yichang Hydrologic Station is much greater than that of the Datong Hydrologic Station. Variability in the quantity of water in these areas will pose a greater challenge to the integrated deployment and management of water resources in the Yangtze River Basin.