基于CMIP5和SWAT的山美水库流域未来蓝绿水时空变化特征

Spatial and temporal variations of blue and green water resources in Shanmei reservoir watershed based on CMIP5 and SWAT

基于山美水库流域1991-2010的实测气象数据,选取CMIP5中2个气候模式(HadGEM2-ES、NoerESM1-M)和2种典型浓度路径(RCP4.5、RCP8.5),对21世纪近期(2031-2050年)、中期(2051-2070年)、远期(2071-2090年)3个时期的日降水、气温数据进行统计降尺度处理;在此基础上,利用SWAT模型对山美水库流域基准期和未来3个时期的蓝水、绿水资源的时空分布特征进行模拟,评估流域未来60年气候变化对蓝绿水资源的影响。结果表明:山美水库流域未来60年预估年均降水量变化幅度为-0.43%~7.16%,平均气温增加约1.72~5.43℃,相较基准期,未来2个气候模式在2种RCP浓度路径下的蓝水资源量约减少12.81%~35.28%,绿水资源量上升约28.45%~36.12%;不同气候情景下流域蓝水、绿水资源变化率呈现出一定的相似性,上游地区均大于下游地区;降雨是蓝水资源时空分布的关键,而农用地分布则直接影响绿水资源的空间分异特征。

Global warming has a profound impact on the hydrological process,which leads to serious problems of regional water shortage.In order to increase the efficient use of available water,it is necessary to predict the impacts of climate change on water resources.Analyzing the spatial and temporal variations of BLUE and GREEN water resources can provide a more reliable basis for regional water resources management and protection.Daily precipitation and temperature data of Shanmei reservoir watershed from two CMIP5 models(HadGEM2-ES and NoerESM1-M)and two representative concentration pathways(RCP4.5 and RCP8.5)for the periods of 2031-2050,2051-2070 and 2071-2090 were statistically downscaling by quantile mapping method based on the measured climate data from 1991 to 2010.Then,to assess the impact of climate change on BLUE and GREEN water resources for the next 60 years,SWAT model was applied to simulate the spatial and temporal distribution of BLUE water and GREEN water during the baseline period(1991-2010)and three future periods.(1)Under the scene of RCP4.5,the annual average precipitation in the future will change by-0.43%to 1.93%compared to the baseline period,and the average temperature will increase by 1.72℃to 3.90℃.Under the scene of RCP8.5,the estimated annual average precipitation will vary by-0.43%to 1.93%,and the average temperature will increase by 1.72℃to 3.90℃.With the increasing of RCP concentration path,the magnitude of change in temperature and precipitation become lager as well.(2)The annual average BLUE and GREEN water resource were 1334.90 mm and 717.18 mm,respectively,in Shanmei reservoir watershed from 1991 to 2010.Compared with the baseline period,the amount of BLUE water resources in the RCP4.5 scenario will decrease by 12.81%to 33.41%,and the amount of GREEN water resources will increase by 28.45%to 33.33%from 2031 to 2090.While the amount of BLUE water resources will decrease by 14.17%to 35.28%,the amount of GREEN water resources will increase by 32.21%to 36.12%under the RCP8.5 scenario.(3)The distribution of BLUE and GREEN water resources in Shanmei reservoir watershed were similar to some degree,with the water resources quantities in upstream sub-basins larger than that in downstream sub-basins.In different climate scenarios,compared with the baseline period,the BLUE water resources in 38 sub-basins decreased by 7%to 43%and the GREEN water resources increased by 15%to 49%.From the perspective of time,the future climate change has a significant impact on BLUE and GREEN water resources in Shanmei reservoir watershed and the precipitation BLUE water resources,while GREEN water resources are directly related to temperature.In the next 60 years,the daily minimum temperature in the basin of Shanmei reservoir watershed will increase between 10.19%and 31.94%,and the precipitation will increase in the range of-4.56%to 9.48%which will lead to a significant decrease in BLUE water resources and a significant increase in GREEN water resources.From a spatial perspective,precipitation was the main factor to influence the distribution of BLUE water resources,while the proportion of agricultural land use in sub-basins had a significant effect on the distribution of GREEN water resources.The spatial variation of BLUE water quantity is related to the climatic characteristics,and the difference of land use types leads to the spatial differentiation of GREEN water resources.