GroMoPo Metadata for Guarani Aquifer System model

The Guarani Aquifer System (GAS) is a strategic transboundary aquifer system shared by Brazil, Argentina, Paraguay and Uruguay. This article presents a groundwater flow model to assess the GAS system in terms of regional flow patterns, water balance and overall recharge. Despite the continental dimension of GAS, groundwater recharge is restricted to narrow outcrop zones. An important part is discharged into local watersheds, whereas a minor amount reaches the confined part. A three-dimensional finite element groundwater-flow model of the entire GAS system was constructed to obtain a better understanding of the prevailing flow dynamics and more reliable estimates of groundwater recharge. Our results show that recharge rates effectively contributing to the regional GAS water balance are only approximately 0.6 km(3)/year (about 4.9 mm/year). These rates are much smaller than previous estimates, including of deep recharge approximations commonly used for water resources management. Higher recharge rates were also not compatible with known(81)Kr groundwater age estimates, as well as with calculated residence times using a particle tracking algorithm.

瓜拉尼含水层系统（Guarani Aquifer System，GAS）是巴西、阿根廷、巴拉圭与乌拉圭四国共享的战略性跨界含水层系统。本文构建了地下水流模型，用于从区域水流格局、水量平衡及整体补给等维度对该含水层系统开展评估。尽管瓜拉尼含水层系统具有大陆级的空间尺度，但其地下水补给仅局限于狭窄的出露带范围内。其中大部分补给量汇入当地流域，仅有少量能够抵达承压含水层区段。研究团队构建了覆盖整个瓜拉尼含水层系统的三维有限元地下水流模型，以期更深入掌握其主导水流动力学特征，并获得更可靠的地下水补给量估算结果。研究结果显示，真正对瓜拉尼含水层系统区域水量平衡产生有效贡献的补给速率仅约为0.6立方千米/年（约4.9毫米/年）。该补给速率远低于此前的估算值，包括以往水资源管理中常用的深层补给近似估算结果。更高的补给速率与已知的(81)Kr地下水年龄估算结果，以及通过粒子追踪算法计算得到的地下水驻留时间均不相符。