Modern rates of water discharge often exceed groundwater recharge in arid catchments. This apparent mass imbalance within a catchment may be reconciled through either groundwater flow between topographic drainages and/or the draining of stored groundwater recharged during pluvial periods. This study investigates discrepancies in the modern hydrologic budget of catchments along the west flank of the Andes in northern Chile (21–25° S), focusing on the endorheic Salar de Atacama basin and adjacent basins. Uncertainty-bounded estimates of modern recharge rates are presented, which do not come close to balancing observed modern groundwater discharge within topographic catchments. Two conceptualizations of hydrogeologic catchments discharging to Salar de Atacama were explored with a simplified two-dimensional groundwater model. Results from the models support the interpretation that subsurface interbasin flow and transient drainage of groundwater from storage are required to balance water budgets along the plateau margin. The models further examine whether this system is still responding to climatic forcing (on paleoclimatic time scales) from pluvial periods and highlight general characteristics for similar plateau margin systems including: (1) water level changes at the plateau margin that are highly sensitive to long-term (100–1,000 years) changes in recharge on the plateau, (2) extent and magnitude of the changes in water table, which are controlled by the distribution of hydraulic conductivity at the margin, and (3) the contributing area to the lower-elevation catchment, which is itself dynamic and not coincident with the topographic boundary.

在干旱的流域，现代水的排放量经常超过地下水的补给量。集水区内这种明显的质量失衡可以通过地形排水系统之间的地下水流和/或在小雨时期补给的存储的地下水的排水来解决。这项研究调查了智利北部（21-25°S）安第斯山脉西翼流域现代水文收支的差异，重点是内生的萨拉尔·德·阿塔卡马盆地和相邻盆地。提出了不确定性的现代补给率估算，这与平衡流域内观测到的现代地下水排放量并不平衡。利用简化的二维地下水模型，探索了向阿塔卡马（Salar de Atacama）排放水文地质流域的两种概念。这些模型的结果支持以下解释：需要地下地下盆地间流动和地下水从存储中的短暂排放，以平衡高原边缘的水量预算。模型进一步检验了该系统是否仍对小雨期的气候强迫（在古气候时间尺度上）作出反应，并强调了类似高原边缘系统的一般特征，包括：（1）高原边缘的水位变化对长期干旱高度敏感。长期（100-1,000年）的高原补给量变化；（2）地下水位变化的程度和幅度，由边际水力传导率的分布控制；（3）较低的贡献面积高程流域，它本身是动态的并且与地形边界不重合。