喜马拉雅山北坡卡鲁雄曲径流与气候变化

以冰川融水补给为主的喜马拉雅山北坡的卡鲁雄曲流域,近20年平均气温以0.34 ^oC/10a的趋势上升,高于西藏年均温0.26 ^oC/10a的增长率,更是明显高于全国和全球气温的增长率,且极端最高温都出现在20世纪90年代。后10年气温 (1994~2003年) 比前十年 (1983~1993年) 升高0.5 ^oC,径流量增加了26%；不同月份径流增加强度不同,10~2月增加了44%,7~9月增加了27%,3~6月增加了24%。径流对气候变化的响应最灵敏 (一年中有8个月的增加趋势通过了α = 0.05的显著性检验),尤其是秋冬季的径流 (增加趋势超过α = 0.01的显著性检验)。受冰川消融和季风影响,不同时期的径流有不同的影响因素,但存在共性,即气温对径流起着积极主导作用,而降水对径流的影响具有不确定性,即正负双面效应。

Hydrological Regime of the Karuxung Watershed in North Himalayas

Water supply of the Karuxung watershed is mainly from melt water and rainfall, therefore both climate warming and precipitation increasing have positive impacts on runoff. Mann-Kendall trend analysis, the Sen's slope estimate and correlation analysis are employed to analyze data from Wengguo hydrometric station and Langkazi meteorological station. The results indicate that runoff, air temperature, precipitation and evaporation all have showed significant upward trends. Of which runoff change is most sensitive to climate change, especially during fall and winter. It is concluded that more trends are observed than are expected to occur by chance. In recent 20 years, the annual mean temperature has increased dramatically with a rate of 0.34 oC every 10 years, which is higher than that of Xizang (Tibet) region which is 0.26 oC every 10 years, and the extremely high temperatures all appeared in the 1990s. For the temperature, the latter 10 years is 0.5 oC higher than the former 10 years, whereas the runoff increased by 26%. Different periods have different growth extents. October to February, July to September and March to June increased by 44%, 27% and 24%, respectively. During ablation period, the runoff change is affected mostly by climate change from April to June, whereas the runoff is affected by climate and precipitation jointly when monsoon comes, and the rainfall influences the runoff with uncertainty. During non-ablation period, runoff change is more obvious for it is influenced by the former months, and its key supply is base flow.