Impacts of Climate Change on Hydrological Processesover the Yellow River Basin

To investigate the hydrological processes in the Yellow River basin that may be affected by climate change in the future, the regional climate model (RegCM3) is nested in one-way mode within a NASA/NCAR finite volume element AGCM (FvGCM) to carry out two 30-year simulations (with a resolution of 20 km) for present day (1961-1990) and the future (2071-2100) under the IPCC SRES A2 scenario. In this scenario, runoff outputs are used to drive a large-scale routing model 0.25° (latitude) ×0.25° (longitude) to project changes in future climate and hydrological processes and extreme hydrological events over the Yellow River basin. The results show that on average the temperature will increase when precipitation is augmented (decreasing in July and August) and evapotranspiration will also increase in the future, with a highly nonuniform spatial distribution over the whole basin in summer. Streamflow will also decrease, especially in flood season from May to October, which may aggravate a crisis of water resources shortages throughout the basin. The increased temperature will also augment snow melt runoff, which may lead to more and earlier spring runoff, and ultimately give rise to changes in the seasonal rainfall-runoff processes and the allocation of intra-annual water resources.