Understanding recharge is an important step in quantifying the sustainability and vulnerability of the groundwater reserve and promoting the adequate implementation of management policies. In southern Brazil, the Guarani Aquifer System (SAG) is increasingly utilised as a source of water for both rural and urban populations and agricultural activities. Being 90% confined, the regional SAG outcrop zones are generally considered the recharge areas, yet local recharge mechanics have yet to be constrained. Water table time series data over a 2-year period from 21 monitoring wells in the southern outcrop zone were investigated to assess the local recharge of the SAG. Recharge estimates calculated using the water table fluctuation (WTF) method were compared to the time series data in terms of auto- and cross-correlation factors. In turn, alluding to the memory effect of the water table that is controlled by the flow pathways to the well and its response to local rainfall events, it is apparent that the local conditions strongly affect water percolating through the unsaturated zone, with evidence of both matrix and preferential flow pathways feeding the monitoring sites. Matrix flow is broadly occurring within the study area, and preferential flow has a more restricted occurrence yet is associated with the highest rate of recharge. Although future studies may quantify the actual recharge amount related to each mechanism, this work explicitly shows that preferential flow mechanisms should not be ignored, providing insight into aquifer sustainability and its vulnerability to modern contaminants.

了解补给是量化地下水储备的可持续性和脆弱性并促进管理政策充分实施的重要一步。在巴西南部，瓜拉尼含水层系统 (SAG) 越来越多地被用作农村和城市人口以及农业活动的水源。由于 90% 的区域受到限制，区域 SAG 露头区域通常被认为是补给区，但当地的补给机制尚未受到限制。对南部露头区 21 口监测井 2 年期间的地下水位时间序列数据进行了调查，以评估 SAG 的当地补给情况。使用地下水位波动 (WTF) 方法计算的补给估算值与时间序列数据在自相关因子和互相关因子方面进行了比较。反过来，暗指由通往井的流动路径控制的地下水位的记忆效应及其对当地降雨事件的响应，很明显，当地条件强烈影响水渗透过非饱和区，有证据表明，基质和优先流路为监测点供电。研究区内基质流广泛存在，优先流的出现较为有限，但与最高的补给率​​相关。尽管未来的研究可能会量化与每种机制相关的实际补给量，但这项工作明确表明不应忽视优先流动机制，从而深入了解含水层的可持续性及其对现代污染物的脆弱性。