降雨能否穿透厚包气带到达潜水面是地下水补给领域争议较大的问题。华北平原“23·7”极端降雨事件相当于华北平原的一次大型入渗试验,为分析潜水埋深如何控制地下水补给提供了契机。本研究以雄安新区白洋淀周边潜水浅埋区4口自动监测井和容城县境内潜水深埋区6口自动监测井为例,分析不同埋深地下水对2023年3日内累积降雨量为289.2 mm的极端降雨事件的响应规律。在潜水浅埋区,暴雨开始后约16 h垂向入渗至潜水面,潜水抬升幅度达1.36~1.79 m;在潜水深埋区,暴雨后河水水位迅速抬升并引发渗漏形成水丘,在潜水回水作用下离南拒马河距离小于6 km的潜水位以较快速度抬升1.38~3.67 m。本研究表明,降雨沿着包气带的垂向入渗是潜水浅埋区地下水的补给来源,暴雨后河水入渗引发的潜水回水是河道附近潜水深埋区地下水补给的主要来源。本文加深了对不同埋深潜水补给机理的认识,对今后分析华北平原乃至其他地下水超采区的水位回升控制机理、生态补水效果具有重要指导意义。

The question of whether rainfall can penetrate a thick unsaturated zone to reach the water table has long been a contentious issue in the field of groundwater recharge. The extreme rainfall event that occurred in the North China Plain from July 23rd to 27th, 2023, equivalent to a large-scale infiltration experiment, provided a valuable opportunity to analyze how groundwater recharge is influenced by the depth to the water table. This study focuses on the Baiyangdian region in the Xiong’an New Area, examining the response patterns of groundwater at different depths during this extreme rainfall event, which delivered a cumulative rainfall of 289.2 mm over three days. Data were collected from four automated monitoring wells in the shallow water table area around Baiyangdian and six automated monitoring wells in the deep water table area within Rongcheng County. In the shallow water table area, vertical infiltration reached the water table approximately 16 hours after the onset of the storm, causing the water table to rise by 1.36 to 1.79 meters. In the deep water table area, river water levels rose rapidly after the storm, leading to leakage that formed a groundwater mound. Due to the backwater effect, groundwater levels within 6 km of the Nanjuhe River rose rapidly by 1.38 to 3.67 meters. This study demonstrates that vertical infiltration through the unsaturated zone is the primary source of groundwater recharge in shallow water table areas. In contrast, in deep water table areas near river channels, post-storm river infiltration and the resulting backwater effect are the main sources of groundwater recharge. These findings improve the understanding of groundwater recharge mechanisms at varying depths and provide valuable insights for analyzing water table recovery processes and the effects of ecological water replenishment in the North China Plain and other regions facing groundwater overexploitation.