喜马拉雅山北坡典型高山冻土区冬季径流过程

喜马拉雅山北坡广泛分布着岛状多年冻土，冻土对径流过程有着不可忽视的影响。卡鲁雄曲是该区唯一有常规水文气象观测资料的流域，海拔范围是4 550~7 200 m，其中5 100 m以上为高山冻土区，以下为深层季节冻土区。近20年径流有较明显的增加趋势，为了探明引起径流变化的原因，采用流域内翁果水文站1983—2003年的月径流资料，通过Mann Kendall趋势检验法，Sen坡度估计以及相关统计分析方法，发现寒冷期（11月至次年3月）径流有不同程度的涨幅，发生突变的年份在1990年左右。尤其以1月份最为明显，后10年比前10年增加了67%。遥相关分析表明，1月份径流与7~12月径流有通过95%显著性检验的相关性，它们的共同作用使得径流变化尤为显著，这是冻土区所特有的。

Winter Runoff in a Typical Alpine Permafrost Region, Tibet-Himalayas

The catchment Karuxung was a typical area and unique with long term observations in the Tibet-Himalayas since 1983. The altitude of the basin varies widely from about 4 550 m to 7 200 m. Owing to higher elevation, the alpine permafrost covers about drainage area of 60%, which limit line is around 5 100 m, above which underlay permafrost and the below is seasonally frozen ground. Mann-Kendall trend analysis, the Sen's slope estimate and correlation analysis were employed to analyze hydrological processes during cold season. The results indicated that the runoff in cold season all had pictured significant increasing trends, of which runoff change in January was the most obvious, which was about 67%. The runoff in January had a high correlation with the runoff from July to December at a significance level of 95%. Therefore, the runoff change in cold season was caused by the former months jointly, which was a characteristic in permafrost region.