Response of streamflow to climate change in the headwater catchment of the Yellow River basin

For the purpose to investigate how streamflow in the headwater catchment of the Yellow River basin will be affected by climate change in the future, four Global Climate Models (GCMs), the Canadian Global Coupled Model CGCM2, CCSR developed by Japanese Research Center of Climate Systems, the Australian developed CSIRO, and the HadCM3 model developed at the Hadley Centre in the United Kingdom, were used to generate low emission scenarios (SRES B2) in this study. Two kinds of downscaling techniques (delta and statistical methods) were used to generate future possible local meteorological variables including temperature and precipitation in the study area. The downscaled data was then used as input to the Soil and Water Assessment Tool (SWAT) hydrological model to simulate the corresponding future streamflow regime in the headwater catchment of the Yellow River basin. Three benchmark periods simulated were 2010–2039 (2020s), 2040–2069 (2050s) and 2070–2099 (2080s). Although four GCMs and two downscaling techniques do not provide identical results, the time series generated by four GCMs and both downscaling methods indicate a significant increasing trend in both maximum and minimum temperature values, and a slight increasing trend in precipitation. The hydrological impact analysis made with the downscaled temperature and precipitation time series as input to the SWAT model suggested an overall decreasing trend in mean annual streamflow in the headwater catchment of the Yellow River basin in three benchmark periods in the future. The scenario analysis made in this study raised questions over the availability of future water resources in the Yellow River basin, which will increase the shortage of water resources at both middle and downstream of the Yellow River basin, where the demand for water resources from industrial, agricultural and domestic sectors will continue to increase in the future.