Abstract: Using the SWAT (Soil and Water Assessment Tool) model and data from the global climate model BCC-CSM 1.1 (Beijing Climate Center Climate System Model 1.1) adopted by the IPCC (Intergovernmental Panel on Climate Change) Fifth Assessment Report,the change of water resource in Honghu watershed under three future climate change scenarios,including RCP (Representative Concentration Pathway) 2.6,RCP 4.5 and RCP 8.5 emission ones,was simulated in this paper.The results indicate that the SWAT model is appropriate to simulate the change in water resource of Honghu watershed.Under the RCP 2.6,RCP 4.5 and RCP 8.5 emission scenarios,the temperature increments are 1.4℃,1.9℃ and 2.4℃,and the variation rates in precipitation are -3.20%,7.60% and 7.90%,respectively.With the increasing in temperature,the amount of evapotranspiration increases for all the three emission scenarios.The runoff is influenced significantly by precipitation.For the different scenarios,the responses of runoff to precipitation are different.Under the RCP 4.5 and RCP 8.5 scenarios,the amounts of surface and groundwater runoffs and flood-peak flow and the times of flood happening in different kinds of return periods all increase.The increasing amount in surface runoff is more remarkable for the RCP 8.5 scenario.Comparatively,the amounts for both of the surface and groundwater runoffs decrease under the RCP2.6 scenario.The variation coefficients of runoff under all these scenarios are bigger than that of the reference period.It means that the possibility of extreme meteorological evens (such as drought and flood) may increase,and the ability to utility and control of water resource in Hongdu watershed may decrease.

Key words: SWAT model, Honghu watershed, Water resource, Global climate model, Emission scenarios