Impacts of climate change on the hydrological cycle in the Haihe basin

Climate change will lead to a significant alteration in regional hydrological cycle. In this paper, the impacts of climate change on the hydrological cycle were analyzed for the Haihe basin. Firstly, the linear regression and Mann-Kendall non-parametric test methods were used to analyze the change characteristics of the hydrological and meteorological elements. The results show a significant increase for temperature, while precipitation decreases slightly, and runoff decreases drastically during the past 50 years. Then the applicability of SWAT (Soil and Water Assessment Tool) model based on the DEM (Digital Elevation Model), land use and soil type was verified in the basin. Finally the precipitation, temperature, runoff and evaporation response processes based on the IPCC AR4 multi-mode climate models under different GHG emission scenarios (SRES-A2, A1B and B1) in the 21st century were discussed in three time periods: 2020s (2011-2040), 2050s (2041-2070), 2080s (2071-2099). The results show that there are systematic positive trends for precipitation and temperature while the trends for runoff and evaporation will differ with sub-areas. Compared with the reference period (1961-1990), the future runoff in the Haihe basin decreases in the previous period while increases in the subsequent period during which the increasing trend are more pronounced in the south than in the north. The future evaporation in the basin shows an increase with a positive trend in the northern part and a negative trend in the southern part.