天山北坡融雪期季节性冻土融化过程分析

利用军塘湖河流域典型试验场2013年11月至2014年3月整个冻结融化期野外观测的季节性冻土温度和水分数据,对融雪期该地区季节性冻土的融化过程和特点进行了分析,研究了融雪期土壤在融化过程中各土壤层的时间与垂直温度和水分的变化,并探讨了融雪期季节性冻土的水文效应。结果表明:1季节性冻土的融化过程可以分为融雪前期、融雪中期和融雪后期3个阶段;2融雪期季节性冻土的温度呈阶段性变化,随着土壤深度的增加,大气温度对土壤温度的影响越小,且存在明显的滞后性;3土壤的水分含量在融雪中期才有所提升,季节性冻土从上下2个方向融解;4融雪中后期的积雪液态含水率对土壤水热状况的影响显著,整个融雪期积雪密度对土壤水热状况影响较小;5季节性冻土的冻融过程对春季融雪径流有着十分重要的影响。

Thawing Process of Seasonal Frozen Soil on Northern Slope of the Tianshan Mountains During Snowmelt Period

In his study,the processes and characteristics of thawing of seasonal frozen soil were analyzed based on the observed data of seasonal frozen soil moisture content and temperature in the typical research field in the Juntanghu River Basin on northern slope of the Tianshan Mountains during the period from November 2013 to March 2014.The temporal and vertical variations of seasonal frozen soil moisture content and temperature at different depths during thawing process of seasonal frozen soil were studied,and the hydrological regime of seasonal frozen soil during snowmelt period was discussed.The results are as follows:① The melting process of seasonal frozen soil could be divided into three stages,i.e.the early,medium and late stages;② There was a staged variation of seasonal frozen soil temperature during snowmelt period,the effect of air temperature on soil temperature was decreased with the increase of soil depth,and there was a time lag of the effect;③ Soil moisture content was increased at medium stage of snowmelt period,seasonal frozen soil was melted from both top and bottom,and the soil temperature was significantly affected by soil moisture content during snowmelt period:④ The effect of liquid water content in snow cover on soil moisture and temperature conditions was significant at medium and late stages of snowmelt period,but that of snow cover density on them was low;⑤ The freezing-thawing process of seasonal frozen soil affected significantly the snowmelt runoff in spring.