未来气候情景下汉江流域中上游径流量变化

Change of Runoff Volume in the Middle and Upper Reaches of Han River Basin under Future Climate Scenarios

汉江中上游涉及南水北调中线工程,径流变化影响可调水量。基于SWAT(Soil&Water Assessment Tool,SWAT)模型,应用最新第六次国际耦合模式比较计划(The Coupled Model Intercomparison Project Phase 6,CMIP6)的5种全球气候模式及4种共享经济路径(Shared Socioeconomic Pathways,SSPs)情景,模拟未来气候变化情景下汉江流域中上游近期(2021-2040年)、中期(2041-2060年)、远期(2061-2080年)径流时空变化。结果表明:(1)与基准期(2000-2014年)相比,各模式情景下降水、气温均呈显著增加趋势,“双碳”情景下,气温、降水增幅均小于高碳情景,流域向湿暖发展;(2)研究区未来径流量在SSP2-4.5和SSP5-8.5路径下呈显著增加趋势,相对历史时期(2000-2014年),在上游近、中、远期部分年份径流减少。(3)研究期内径流量年内分配更加均匀,11月-翌年6月枯水期径流量增加,提高了流域的抗旱能力;(4)空间上,径流量增加以中部和东部为主,近期内高碳情景下径流量有所减少,但长时期内表现为增加趋势,南水北调中线工程水源地未来径流量呈增加趋势,但其增量不能完全满足远期南水北调调水量增幅,可能对中下游水资源供给带来挑战。

The middle and upper reaches of the Han river are involved in the South-to-North Water Diversion Project,and the change of runoff affects the amount of adjustable water.In order to investigate the change of runoff in the middle and upper reaches of the Han river basin under climate change,based on the SWAT(Soil&Water Assessment Tool,SWAT)model,we have developed a new model,which is based on the Soil&Water Assessment Tool(SWAT),five global climate models and four Shared Socioeconomic Pathways(SSPs)scenarios are simulated under future climate scenarios(2021−2021)in the upper and middle reaches of the Han river Basin.Based on the SWAT(Soil&Water Assessment Tool)model,we applied five global climate models and four Shared Socioeconomic Pathways(SSPs)scenarios from the latest 6th Coupled Model Intercomparison Project Phase 6(CMIP6),and simulated the temporal and spatial changes of runoff in the middle and upper reaches of the Han river basin in the near term(2021−2040),middle term(2041−2060),and long term(2061−2080)under the future changes of climate scenarios.The results showed that:(1)compared with the baseline period(2000−2014),rainfall and temperature increased significantly under all model scenarios,and under the"two-carbon"scenario,the increase in temperature and precipitation was smaller than that of the high-carbon scenario,and the watershed was developing towards wetting and warming.(2)The future runoff in the study area showed a significant increasing trend under the SSP2-4.5 and SSP5-8.5 pathways,relative to the historical period,and the runoff decreased in some years in the upstream near,middle and far periods.8.5 pathways show a significant increasing trend,relative to the historical period,and runoff decreases in some years in the upstream near-,mid-,and far-periods.(3)Intra-annual distribution was more even,and runoff increased during the dry period from November to June of the following year,which improved the drought-resistant capacity of the basin.(4)Spatially,the increase in runoff was dominated by the central and eastern parts of the country,and runoff decreased under the high-carbon scenario in the near future,but showed an increasing trend in the long term,with an increasing trend in future runoff at the source area of the South-to-North Water Diversion Project.