GroMoPo Metadata for Altar Valley (High Andres) model

Groundwater and surface water sourced from the high Andes of Argentina are highly important for societal, agricultural, and domestic usage in the foothills and valleys, less than hundred kilometers away from the headwaters. Despite their importance, efforts to provide estimates and predictions of surface water and especially groundwater sources and sinks have been limited. During most of the year, precipitation in the high Andes falls primarily as snow, with minimal rainfall over the summer. A widespread lack of measurements and statistical analysis in the region makes it difficult to understand groundwater storage and flow patterns in the Andean watersheds. The contribution of mountain snowmelt to groundwater is a key component of recharge to this area. While this study is limited to a small watershed in the Altar valley of the Central Andes of Argentina, it is representative of most of the Dry Andes region, which runs from Bolivia south to a latitude of 35S between Argentina and Chile. This region is characterized by steep and abrupt topography, highly fractured bedrock, and large fault systems. Here, we investigate the groundwater flow system through observations from pressure transducers and weather stations installed by a mining company exploring the area. We use this data to create a MODFLOW groundwater model of the watershed and develop then a sensitivity analysis to gain insight into the hydrologic system. We explore changes in hydraulic conductivity with depth and reduction in recharge due to uncertainties in sublimation and evaporation and potential future trends. We then analyze heads, surface outflows to assess the impact of these changes within the hydrologic system. In addition, ages distribution in particles from the one well and the river are analyzed. ? This research contributes to the understanding of groundwater recharge and discharge estimates and the hydraulic behavior of upland mountainous watersheds toward better water management in the area.

源自阿根廷安第斯高海拔区域的地下水与地表水，在距源头不足百公里的山麓与河谷地带，对当地社会生产、农业灌溉及生活用水至关重要。尽管此类水资源意义重大，但针对地表水、尤其是地下水的源汇项开展估算与预测的相关研究仍较为有限。该区域一年中的多数时段，安第斯高海拔地带的降水主要以降雪形式出现，夏季降雨稀少。本区域普遍缺乏观测数据与统计分析，导致学界难以明晰安第斯流域的地下水储存与径流模式。山地融雪对地下水的补给贡献，是该区域地下水补给的关键组成部分。尽管本研究仅聚焦于阿根廷中部安第斯山脉阿尔塔谷（Altar Valley）的一处小型流域，但其可代表从玻利维亚向南延伸至阿根廷与智利交界的南纬35°沿线的绝大多数干旱安第斯区域。该区域以陡峭险峻的地形、高度破碎的基岩以及大型断裂系统为典型特征。本研究依托某矿业公司在该区域勘探期间布设的压力传感器与气象站观测数据，对地下水流系统展开探究。研究团队利用此类数据构建了该流域的MODFLOW地下水模型，并随后开展敏感性分析，以深入解析该水文系统。我们探究了水力传导度随深度的变化，以及由升华、蒸发不确定性与潜在未来趋势引发的补给量缩减情况。随后分析了水头变化与地表径流量，以评估上述变化对水文系统的影响。此外，还对取自单口井与河流的沉积物颗粒的年龄分布展开了分析。本研究有助于深化对地下水补给与排泄估算的认识，以及山地高原流域的水力行为特征，从而为该区域的水资源精细化管理提供支撑。