近50 a来乌鲁木齐河源区径流变化及其机理研究

 乌鲁木齐河源区径流是供给中下游地区和乌鲁木齐市的重要水源。通过对河源区3个水文断面（1号冰川、空冰斗和总控）有观测记录以来的径流变化研究，一方面提供径流观测的最新资料，使人们对乌鲁木齐河源区径流近期变化有新的认识；另一方面通过对气候、冰川变化的综合分析，揭示乌鲁木齐河源区径流近50 a变化事实和可能的原因。结果表明：河源区3个水文断面径流自有观测记录以来整体上呈增加趋势，其中总控水文断面径流虽有增加，但不显著。影响3个水文断面径流变化的因素不同，1号冰川水文断面径流变化受控于冰川区热量条件，当消融期气温大于2 ℃时，径流呈加速增长。1号冰川径流不仅包含了冰川对气候变化的瞬时响应，也包含了冰川对气候变化的滞后响应，由冰川物质平衡和面积计算的冰川体积损失量变化较好地验证了径流变化。对于空冰斗融雪径流，降水量多寡是导致径流变化的主导因素，但冰斗区固态降水多，气温亦起着不可忽视的作用。总控水文断面径流大小与气温和降水关系比较复杂，表现为近年来气温和降水增加，径流却有下降趋势，这可能与河源区实际蒸散增强、冰川快速退缩导致径流峰值已经出现、大范围冻土消融导致的地下渗漏量增多等原因有关。

Runoff variation and mechanism at headwaters of Urumqi River in recent 50 years

Runoff generated at the headwaters of Urumqi River provides the principal water resource to the middle and lower reaches and Urumqi city.Study on the long-term observation of runoff change is of great significance for the reasonable utilization of water resources and development of good watershed management strategies in the arid region of northwest China.Here we systematically analyzed variation in runoff from three hydrological stations located at the source area of Urumqi River in recent 50 years,and revealed the possible causes,relating it to changes in climatic conditions and glacier mass loss.The results showed that there were generally increasing trends in runoff of these three hydrological stations;whereas the runoff of Zongkong station exhibited no significant increase over the study period.Factors influencing runoff change of three hydrological stations were different.For Glacier No.1 station,the runoff change was mainly controlled by heat conditions in glacieriezd region and the runoff showed an accelerated growth when the temperature in the melt season was more than 2 ℃.The runoff at the station included not only the immediate and direct response of glacier to climate change,but also the indirect and lagged response.And changes in volume loss of Glacier No.1 corresponded well with the runoff variations.For Empty Cirque hydrological station,the snow melt water and rainfall were source of runoff,so precipitation was the dominating factor affecting runoff change.However,the air temperature also should not be ignored.Under the condition of lower temperature and plentiful precipitation,the limited snow melt would only produce less runoff.The relation between runoff and climate change was somewhat more complicated for Zongkong station.Against the background of temperature rising and precipitation increasing,runoff showed a drop tendency in recent years which might be related to many factors,such as actual evapotranspiration enhancing,runoff peak appearing due to rapidly glacier recession,underground leakage increasing caused by extensively permafrost melts,etc.