Abstract:  Identification of regime evolution process of phreatic water table under changing environment (climate change and human activities) is the main scientific problem in the field of water resources in China and even globally. In order to analyze the spatial and temporal dynamic changes of phreatic water table under multiple influencing factors, considering precipitation and groundwater exploitation, the spatial and temporal variation of regional phreatic water table from January 2016 to December 2019 in Khorqin district, Tongliao City was analyzed using MannKendall (MK) trend test and grid algebra method. In addition, crosswavelet analysis, Spearman correlation coefficient and multiple linear regression method were used to further quantify the influence of precipitation and groundwater exploitation on the phreatic water table in different regions. The results show that, during the study period, the phreatic water table in Khorqin district shows a general decline  trend, with an average annual decrease of 0.36 m, and the decrease of phreatic water table in central and western areas is more severe. According to the spatial distribution characteristics of the phreatic water table difference, the study area is divided into phreatic water table dynamic balance area, decline area and  serious decline area, which account for 9.88%, 49.65% and  40.47%,  of the total area of the study area, respectively. The phreatic water table in the dynamic balance region is mainly influenced by precipitation, only slightly affected by groundwater exploitation. In the phreatic water table decline region and serious decline region, the phreatic water table is more affected by exploitation than by precipitation.

Key words:  , Khorqin district, Tongliao City, phreatic water table dynamics, precipitation, groundwater exploitation, cross wavelet analysis