使用NASA-NCAR全球环流模式FvGCM结果驱动高分辨率区域气候模式RegCM3 (20 km),进行1961～1990年当代气候模拟(控制试验)和2071～2100年IPCC A2排放情景下未来气候情景模拟(A2情景模拟试验)。将RegCM3同高分辨率大尺度汇流模型LRM(分辨率0.25°×0.25°)连接,分析水文极端事件在A2情景下相对于当代气候的变化,预估未来气候变化对我国黄河和长江流域水文极端事件的影响。结果表明：(1)未来黄河流域径流年变率增大,月变率减小,日变率在头道拐站以上流域减小,以下流域增大。未来兰州以上半湿润地区,流域东南部湿润区出现径流量峰值的可能性增大,而流域西北部干旱半干旱区出现径流量百分位极值的可能性减小。未来黄河流域中游地区发生流域洪水的风险在夏季月份减少,其余月份均增大。(2)未来长江干流径流年际变率增大,上中游地区径流日和月变率减小,下游地区略有增大；未来汉江流域径流量的年、月和日变率均增大。未来长江干流发生流域洪水的风险在夏季明显降低,而汉江流域各月发生流域洪水的可能性均增大。
A regional climate model (RegCM3) nested in one-way mode within a NASA/NCAR finite volume element AGCM (FvGCM) is used in this study. Two sets of multi-decadal simulations are conducted at 20-km grid spacing for present day (1961-1990) and future climates (2071-2100, A2 scenario). The runoff outputs are used to drive a large-scale routing model (resolution, 0.25°×0.25°), to project the effect of future climate change on hydrological extreme events over the Yellow River and Yangtze River basins. The results show that the annual variability of the streamflow over the Yellow River will increase, and the monthly variability will decrease. The diurnal variability will decrease upstream and increase downstream of Toudaoguai station. A greater possibility of the largest streamflow percentile will exist in the upper reaches of Lanzhou station in sub-humid areas and southeast of the Yellow River basin in humid areas, whereas the possibility is less in the arid and semi-arid areas of the northwestern basin. The flood disaster risk will increase in future over the middle reaches of the Yellow River except in the summer season. The annual variability of the Yangtze River may increase, and the diurnal and monthly variability may decrease in the upper and middle reaches and rise slightly in the lower reaches in future. The annual, monthly, and diurnal variability of the streamflows all increase in future over the Hanjiang River basin. The flood disaster risk may decrease over the Yangtze River, especially in summer, and the probability of flooding in the Hanjiang River basin will increase in each month.