Articles | Volume 21, issue 4
Hydrol. Earth Syst. Sci., 21, 1911–1927, 2017
https://doi.org/10.5194/hess-21-1911-2017
Hydrol. Earth Syst. Sci., 21, 1911–1927, 2017
https://doi.org/10.5194/hess-21-1911-2017

Research article 05 Apr 2017

Research article | 05 Apr 2017

Climate change impacts on Yangtze River discharge at the Three Gorges Dam

Steve J. Birkinshaw1, Selma B. Guerreiro1, Alex Nicholson2, Qiuhua Liang1, Paul Quinn1, Lili Zhang3, Bin He4, Junxian Yin3, and Hayley J. Fowler1 Steve J. Birkinshaw et al.
  • 1School of Civil Engineering and Geosciences, Newcastle University, Newcastle, UK
  • 2Ove Arup and Partners, Admiral House, 78 East St., Leeds, UK
  • 3State Key Laboratory of Simulation and Regulation of Water Cycle in River Bain, China Institute of Water Resources and Hydropower Research, Beijing, China
  • 4School of Hydraulic Engineering, Dalian University of Technology, Dalian, China

Abstract. The Yangtze River basin is home to more than 400 million people and contributes to nearly half of China's food production. Therefore, planning for climate change impacts on water resource discharges is essential. We used a physically based distributed hydrological model, Shetran, to simulate discharge in the Yangtze River just below the Three Gorges Dam at Yichang (1 007 200 km2), obtaining an excellent match between simulated and measured daily discharge, with Nash–Sutcliffe efficiencies of 0.95 for the calibration period (1996–2000) and 0.92 for the validation period (2001–2005). We then used a simple monthly delta change approach for 78 climate model projections (35 different general circulation models – GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to examine the effect of climate change on river discharge for 2041–2070 for Representative Concentration Pathway 8.5. Projected changes to the basin's annual precipitation varied between −3.6 and +14.8 % but increases in temperature and consequently evapotranspiration (calculated using the Thornthwaite equation) were projected by all CMIP5 models, resulting in projected changes in the basin's annual discharge from −29.8 to +16.0 %. These large differences were mainly due to the predicted expansion of the summer monsoon north and west into the Yangtze Basin in some CMIP5 models, e.g. CanESM2, but not in others, e.g. CSIRO-Mk3-6-0. This was despite both models being able to simulate current climate well. Until projections of the strength and location of the monsoon under a future climate improve, large uncertainties in the direction and magnitude of future change in discharge for the Yangtze will remain.

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Short summary
The Yangtze River basin in China is home to more than 400 million people and susceptible to major floods. We used projections of future precipitation and temperature from 35 of the most recent global climate models and applied this to a hydrological model of the Yangtze. Changes in the annual discharge varied between a 29.8 % decrease and a 16.0 % increase. The main reason for the difference between the models was the predicted expansion of the summer monsoon north and and west into the basin.