The Allende–Piedras Negras (APN) aquifer is located between the states of Texas (United States [U.S.]) and Coahuila (Mexico). The Rio Grande crosses the aquifer, acting as a natural and political divide between the countries. However, it remains unclear whether the APN aquifer can be considered a truly transboundary aquifer flow system, which would potentially require joint management by two different administrative jurisdictions. The main purpose of this study was to evaluate the transboundary nature of this aquifer. This was achieved by developing a detailed hydrogeological model to analyze the direction of volumetric fluxes within the APN aquifer using Visual MODFLOW. The model simulated a spatially averaged cumulative drawdown of 0.76 m for the entire aquifer over an 18‐year modeling period (2000–2017). The flow convergence zone, previously located below the Rio Grande, has shifted to the U.S. side in most locations, driven by higher pumping rates of the wells located near the river. This shift of the convergence zone from one country to the other means that groundwater recharge from one side flows underneath the river to the other side. This qualifies the APN aquifer as a “transboundary groundwater flow system.” The procedure followed in this study may be applied to other aquifers that straddle the U.S.–Mexico border and may motivate future modeling studies on other poorly studied transboundary aquifers around the world and thereby enable bi‐national aquifer management.

中文翻译：

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阿伦德-Piedras Negras含水层的跨界性质，采用数值模型方法

阿连德-皮德拉斯内格拉斯（APN）含水层位于德克萨斯州（美国）和科阿韦拉州（墨西哥）之间。大里约热内卢穿越含水层，这是两国之间的自然和政治鸿沟。但是，目前尚不清楚是否可以将APN含水层视为真正的跨界含水层流量系统，这可能需要两个不同的行政辖区共同管理。这项研究的主要目的是评估该含水层的跨界性质。这是通过开发详细的水文地质模型以使用Visual MODFLOW分析APN含水层内体积通量的方向来实现的。该模型在18年的建模期间（2000-2017年）模拟了整个含水层的平均空间平均缩水0.76 m。流动收敛带 由于位于河边的油井的抽水率较高，以前位于大里奥河下方的油井已经转移到了美国大部分地区。汇合区从一个国家转移到另一个国家，意味着地下水的补给从一侧从河流下方流到另一侧。这使APN含水层符合“跨界地下水流动系统”的条件。本研究中遵循的程序可能适用于横跨美国-墨西哥边界的其他含水层，并可能激发未来对世界各地其他研究不足的跨界含水层进行建模研究，从而实现对两国含水层的管理。汇合区从一个国家转移到另一个国家，意味着地下水的补给从一侧从河流下方流到另一侧。这使APN含水层符合“跨界地下水流动系统”的条件。本研究中遵循的程序可能适用于横跨美国-墨西哥边界的其他含水层，并可能激发未来对世界各地其他研究不足的跨界含水层进行建模研究，从而实现对两国含水层的管理。汇聚区从一个国家转移到另一个国家，意味着地下水的补给从一侧从河流下方流到另一侧。这使APN含水层符合“跨界地下水流动系统”的条件。本研究中遵循的程序可能适用于横跨美国-墨西哥边界的其他含水层，并可能激发未来对世界各地其他研究不足的跨界含水层进行建模研究，从而实现对两国含水层的管理。