兰江流域气候与水文模拟研究

A study on climatic and hydrological modeling in Lanjiang basin

该文建立了气候-水文嵌套模式,用于气候变化情景下流域气候、水文模拟,并在此基础上进行水资源评估。首先应用20km高分辨率的区域气候模式RegCM3,嵌套全球环流模式FvGCM的大气部分,在中国东部地区进行了两组30a积分的模拟试验,即控制试验和未来预测试验。控制试验(1961—1990年)结果表明,RegCM3能较细致地刻画浙江省的地形分布,模拟的浙江省的多年平均气温和降水均呈现出明显的地形特征,与实况较为符合。兰江流域年平均气温模拟较好,但夏季降水模拟量明显偏低。在未来预测试验中,构建了SRESA2排放情景下兰江流域2071—2100年的气候变化情景。然后,用兰江流域的历史观测资料对分布式水文模型DHSVM进行了率定和验证,该模型较好地再现了兰江流域的历史径流过程,具有较好的模拟特性。最后,将RegCM3的两组试验结果输入到DHSVM中,驱动模型进行水文模拟。模拟结果表明:相对于1961—1990年,兰江流域2071—2100年各月的平均气温均呈上升趋势,年平均气温上升幅度达2.84℃;年降水量也将增加,主要发生在4—7月的汛期,可能会导致汛期洪涝灾害发生频率上升;年径流深变化与年降水量变化基本一致,汛期径流将明显增加。在全球持续变暖的背景下,兰江流域未来高温热浪和洪涝等气候、水文极端事件有可能进一步加剧。

A climatic and hydrological nesting model system was established to simulate the climate and hydrology conditions under the SRES A2 scenario and assess impacts of climate change on water resources in the Lanjiang basin.Two sets of 30-year integral experiments i.e.the control experiment and the future prediction experiment,were conducted in the Eastern China by using the 20 km high resolution regional climate model RegCM3 coupling with the atmosphere part of global climate model FvGCM.The results of the control experiment from 1961 to 1990 indicate that both the simulated annual averaged temperature and precipitation in Zhejiang province have distinct topographic characters and agree with the observations since the detailed topography of Zhejiang province is incorporated into the high resolution RegCM3.The simulated annual averaged temperature of Lanjiang basin is quite consistent with the observed one,but the simulated annual precipitation is less than the observed,especially in summer.In the future prediction experiment,the climate change scenario of Lanjiang basin from 2071 to 2100 was set up under the SRES A2 scenario.Then the distributed hydrological model DHSVM was calibrated and validated using observed data.The hydrological model could reproduce the past runoff process of Lanjiang basin quite well,reflecting its high modeling ability.At last,the two sets of simulated results by RegCM3 were put into DHSVM to drive the hydrological simulation in Lanjiang basin.The simulated results show that the averaged temperature in each month will all rise from 2071 to 2100 compared to the one from 1961 to 1990,and the annual temperature will increase by 2.84 ℃.The annual precipitation will also increase especially in the flood season from April to July,which could results in the rising of flood frequency in the basin.The annual runoff will also increase in step with more annual precipitation,especially in the flood season.Under the global persistent warming scenarios,the climate extreme events such as high temperature,heat waves and floods will probably be more severe in the basin.