季节性冻土区融雪入渗对地下水的补给作用分析

Analysis on recharging effect from snowmelt infiltration on groundwater within seasonal frozen-soil region

为了分析季节性冻土区春季融雪入渗对地下水的补给作用,通过对小型野外试验场地气温、地下水位和土壤温度以及土壤湿度动态的系统监测,分析了冻结期和融冻期间地下水位动态的变化特征及其与相关环境要素的对应关系。在此基础上,分析了冻土层渗透性的影响因素,提出了季节性冻土区不同冻融阶段相应的地下水补给模式。研究结果表明:季节性冻土区大气降水入渗量应分非冻结期、冻结期以及融冻期三个时段进行计算,其中冻结期大气降水以降雪形式出现,对地下水无入渗补给作用;春季融冻期间,在冻结期内产生的积雪开始融化,可单独或与大气降雨一起入渗,并对地下水产生较为明显补给作用,但入渗补给系数相对较小,在本文的实例研究场地内,融冻期的融雪(降水)入渗补给系数仅为非冻结期大气降水入渗系数的1/2左右。

In order to analyze the recharging effect from snowmelt infiltration on groundwater within the seasonal frozen-soil region,the corresponding relationship between the dynamic variation characteristics of the groundwater level and the correlative environmental factors during both the frozen period and the frozen-thaw period is analyzed herein through the systematic dynamic monitoring on the ground temperature,groundwater level,soil temperature and soil humidity of a small-sized field experiment site. On the basis of this,the impacting factor of the permeability of frozen-soil layer is analyzed,and then the corresponding groundwater recharging modes for different frozen-thaw stages in the seasonal frozen-soil region are proposed. The study result shows that the infiltration of the atmospheric precipitation within the seasonal frozen-soil region must be calculated in three time intervals,i. e.,non-frozen period,frozen period and frozen-thaw period,in which the atmospheric precipitation during frozen period occurs in form of snowfall without any recharging effect on groundwater. During the frozen-thaw period in spring,the accumulated snow begins to thaw,which can infiltrate alone or together with the atmospheric precipitation and has a more significant recharging effect on groundwater,however,the infiltration recharging coefficient is relatively less. In the area of the actual case for the study made herein,the recharging coefficient of the snowmelt（ precipitation） infiltration during the frozen-thaw period is only about 1/2 of the infiltration coefficient of the atmospheric precipitation during the non-frozen period.