全球升温1.5℃和2.0℃对长江寸滩站以上流域径流的影响

基于多领域间影响模型比较计划推荐使用的4个全球气候模式GCM数据（GFDL、Had、IPSL和MIROC)，分别驱动SWIM、SWAT、HBV和VIC水文模型模拟长江寸滩站以上流域径流量，研究全球升温1.5℃和2.0℃情景下研究区径流量变化。研究表明：（1）在全球升温1.5℃时，水文模型和GCMs模拟的年径流量增幅分别在 5.5%~8.3%和3.5%~11.4%之间；在全球升温2.0℃时，水文模型模拟的径流量增幅在4.8%~6.7%，IPSL模拟的年径流量呈微弱减少趋势，HAD和MIROC模拟的年径流量分别增加6.7%和19%。来自GCMs的不确定性分别是来自水文模型的2.6和 2.1倍；（2）在两个不同升温条件下，月径流量集合平均的占比与基准期各月径流量的占比表现出高度一致性，但是升温1.5℃和2.0℃时的月最大径流量占比分别为47.8%和40.5%，表明在未来升温时段内，月径流量占比变化并不显著，但是极端月径流的变化较大；（3）全球升温1.5℃时，枯、丰水期日径流量增幅分别为3%和10%，但枯、丰水期径流贡献率变化幅度都不大。全球升温2.0℃时，枯、丰水期增幅分别为3.6%和8%，但枯、丰水期径流贡献率都呈下降趋势。全球升温1.5℃和2.0℃时，50年一遇（P=2%）的洪水流量，将分别比基准期增加26.3%和20.7%。基准期50年一遇的洪水将可能变成20年一遇，多年平均最大日径流量较基准期也有增加。

Effects on Runoff Above the Cuntan Station Area in the Yangtze River Basin Under the 1.5℃ and 2.0℃ Global Warming

Four Global Climate Model(GCM) data(GFDL, Had, IPSL and MIROC) recommended by the Inter-Sectoral Impact Model Inter-comparison Project drive SWIM, SWAT, HBV and VIC hydrological models to simulate runoff above the Cuntan hydrological station in the Yangtze River and to study the runoff changes under the global warming of 1.5℃ and 2.0℃. The results showed that:(1) In the 1.5℃ warming period, the hydrological model and GCMs simulated annual runoff increases of 5.5%~8.3% and 3.5%~11.4%, respectively; in the 2.0℃ warming period the hydrological model simulated a runoff increase of 4.8% to 6.7%. The IPSL simulated annual runoff showed a slight decrease, and the annual runoffs simulated by HAD and MIROC increased by 6.7% and 19%, respectively. The uncertainties from GCMs are 2.6 and 2.1 times that of hydrological models, respectively.(2) Under the conditions of two different global warming, the proportion of the monthly runoff collection averages is highly consistent with the proportion of monthly runoff during the reference period, but the proportion of the monthly maximum runoff under 1.5℃ and 2.0℃ global warming was 47.8% and 40.5% respectively, indicating that the monthly runoff contribution did not change significantly in the future warming period, but the extreme monthly runoff changed significantly.(3) Under 1.5℃ global warming, daily runoff increases in the dry and wet periods are 3% and 10%, but the change rates of runoff in the dry and wet periods are not large. Under 2.0℃ global warming, the increase in the dry season and the wet season was 3.6% and 8%, respectively, but the contribution rates of runoff in the dry and wet periods all showed a downward trend. Under 1.5℃ and 2.0℃ global warming, the flood flow once in 50 years(P = 2%) will increase by 26.3% and 20.7% respectively over the base period. The floods in the 50-year period of the reference period will likely become once in 20 years, and the average annual maximum runoff volume for many years will also increase over the reference period.