季节冻土对包气带水分迁移的影响

Influence of seasonal frozen soil on moisture migration in the aerated zone

采用智能化土壤墒情监测仪,对东北吉林集安季节冻土带进行地温和含水率观测,历时一个水文年。通过分析不同深度地温、含水率随时间的变化,研究地温场变化、降水入渗等因素对水分迁移的影响。寒季,气温急剧下降,地温随深度增加而增高,气态水在包气带上部的低温带凝结,当凝结速率大于渗透速率时,含水率不断增加,水分蓄积。季节冻土形成后,孔隙水以固态水的形式储存,是包气带上部水分主要的聚集期。暖季,地温随深度增加而降低,气态水向下运移凝结,即使降水入渗量很大也不会引起水分蓄积。因此,温度场控制着气态水凝结方向,是引起包气带内水分运移的重要影响因素之一。

In this work,the intelligent monitors of soil moisture were used to observe the soil temperature and moisture content in the seasonal frozen soil region of Ji＇an in Jilin in Northeast China,in which the monitoring lasted a hydrological year.By analyzing changes with time of soil temperature and moisture content at different depths,the influence of variation in the soil temperature field,infiltration of precipitation and other factors on moisture migration is examined.In the cold season,gaseous water condenses at the low temperature band of the upper aerated zone since the temperature drops sharply and soil temperature increases with depth.When the condensation rate is greater than the rate of infiltration,the water accumulates and leads to the increasing moisture content.After seasonal frozen soil forms,the pore water is stored in the form of solid water.The season is a major gathered period of water.However,in the warm season,gaseous water transports downward and condenses as soil temperature decreases with depth.A large amount of rainfall infiltration will not cause water accumulation in the aerated zone.Therefore,the temperature field controls the direction of gaseous water condensation,which is one of the important factors affecting moisture migration in aerated zone.