Impact of future climate change on runoff in the head region of the Yellow River

The head region of the Yellow River is the key area where climate change would affect the hydrological process, since it is in a high elevation and cold area. Temperature and precipitation are two important meteorologic factors influencing the hydrological process. In this study, runoff change was evaluated as a result of the hydrological process change and an evaluation of runoff response to the two factors was made. Data derived from the results of seven general circulation models (GCMs) under two intergovernmental panel on climate change scenarios (A2 and 132) were used as future climate scenarios. First, factual and future climate change is analyzed according to data observed and obtained from GCMs. It was found that temperature has been increasing since 1961 and would continue in the future. The change in future precipitation also showed an increasing tendency. Then, a distributed hydrologic model, taking into account the effect of snow and frozen soil, was developed based on observed data in order to investigate the impact of temperature and precipitation change on runoff. Simulated runoff corresponding to climate scenarios indicates that the runoff amount would change lightly before 2020 and then would decrease approximately 5% per year. Analysis of runoff characteristics showed that runoff would increase in the dry season, resulting in relatively uniform distribution of seasonal runoff. Large variablility in annual runoff in the future implies a high probability and severity of flooding as well as droughts.