气侯变化背景下黑河上游春季融雪洪水预估研究

气候变暖将导致高山区冰冻圈加剧融化,一方面融水资源时空分布的不确定性增大;另一方面,融水洪水灾害发生的频度和强度也将发生改变。基于气象、水文数据和MODIS积雪覆盖数据,利用融雪径流模型(SRM),对1990—2012年共23年祁连山黑河札马什克控制区融雪期径流进行模拟与验证。结果表明：SRM在该流域具有较高的模拟精度（纳什系数为0.91),可用于分析和预估控制区径流强度变化。为此,采用黑河流域气温、降水降尺度数据,预估了未来气候变化背景下积雪范围变化及不同重现期洪水变化趋势。结果显示,与基准期相比,在RCP2.6、RCP4.5和RCP8.5情景下,最大积雪范围可减小3%~7%,且随着海拔升高,变化愈剧烈。RCP2.6情景下因气温和降水变化幅度较小,到21世纪末各重现期洪水强度保持在10%以内波动;RCP4.5情景下,各重现期洪水强度最高增大约20%;在RCP8.5情景下,各重现期洪水强度最高可增大超30%。相关分析结果显示,不同重现期洪水径流与气温和降水均具有较强相关性：重现期越长,洪峰与气温的相关性越大;重现期越短,洪峰与降水的相关性越大。通过预估气候变化背景下的融雪性洪水事件强度及重现期变化,有助于有效开展区域洪水风险管理、提高洪水资源的利用价值。

Spring snowmelt flood estimate in the upper Heihe River under climate change

Climate warming will lead to accelerate the melting speed in high-mountain cryosphere. On the one hand, it develops the uncertainty of the spatiotemporal distribution, on the other hand, it causes changes in the frequency and intensity of snowmelt floods. Based on meteorological, hydrological and MODIS snow cover data, using the Snowmelt Runoff Model (SRM) to simulate and verify the spring runoff result during the snowmelt period from 1990 to 2012 in Zarmsk controlling area in the Heihe River basin. Results show SRM has a high accuracy (Nash-Sutcliffe efficiency coefficient = 0.91), which can be used to predict the future flood intensity changes in studying area. In order to predict the trends under the different future climate change background, the temperature and precipitation downscaling data were used. The results show that the maximum snow cover area can be reduced about 3%-7% in different RCPs scenario compared with the reference period, and the change is more relative to the increase of altitude. By the end of this century, the flood intensity shows different changes according to climate change situations compared with the reference period: in RCP2.6, due to the small changes of the temperature and precipitation, it will change slightly within 10%; in RCP4.5, it will increase about 20%; in RCP8.5, may be rise around 30%. The result of correlation analysis shows that the correlation between flood intensity and temperature/precipitation is strong for different return period floods: the longer return period, the higher correlation between flood peak flow and temperature; and the shorter return period, the higher correlation between flood peak flow and precipitation. By projecting the frequency and intensity of snowmelt flood events under climate change, it is helpful to analyze the potential risk scope, carry out regional flood risk management and increase the value of flood water resources.