GroMoPo Metadata for Lower Piura Sub-basin Aquifer model

The Lower Piura Sub-basin Aquifer is a vital source of water in the north of Peru. Despite its importance, few local studies describe this formation. Most are limited to reporting hydraulic characteristics and abstraction rates, lacking a broader analysis. This article characterizes the aquifer, presenting the development of a conceptual and mathematical model with sparse data, completed using several assumptions and interpolations. The model will improve understanding of the aquifer system and the impacts of abstraction. The aquifer system includes an unconfined aquifer connected to a confined aquifer through an aquitard. Steady-state and transient-state models from 2004 to 2014 were used. The development and calibration of the model have led to proper identification of hydraulic parameters and boundary conditions, clarifying the dynamics of the system. In the unconfined aquifer, groundwater flows towards the south-west without significant variation in the water table. Conversely, the piezometric surface of the confined aquifer shows a cone of depression with a falling trend of 1.6 m/year between 2004 and 2014. Outflows include abstractions (48.42 x 10(6) m(3)/year), gaining surface waters (6.33 x 10(6) m(3)/year), and sea discharge (18.50 x 10(6) m(3)/year). Inflows are from irrigation return (34.67 x 10(6) m(3)/year) and from the Higher Piura Aquifer (27.23 x 10(6) m(3)/year). The imbalance of 11.24 x 10(6) m(3)/year is abstracted from aquifer storage leading to hydraulic head drops and flow changes, revealing a clearly unsustainable overexploitation scenario that impacts more intensively the confined aquifer. Model results provide the basis to understand how this is happening and help to suggest strategies to alleviate the current aquifer situation.皮乌拉次盆地下层含水层（Lower Piura Sub-basin Aquifer）是秘鲁北部至关重要的水源。尽管其战略意义重大，目前针对该含水层的本土研究仍较为匮乏：多数研究仅局限于报道其水力特征与开采速率，缺乏系统性的全面分析。本文针对该含水层开展系统表征，基于稀疏数据结合多项假设与插值方法，构建了概念模型与数学模型，以深化对含水层系统及开采影响的认知。该含水层系统包含潜水含水层（unconfined aquifer）与承压含水层（confined aquifer），二者通过弱透水层（aquitard）相连通。研究采用2004年至2014年的稳态与非稳态模型开展分析，通过模型构建与校准，准确识别了水力参数与边界条件，阐明了系统的水文动力学机制。在潜水含水层中，地下水整体向西南方向径流，地下水位未出现显著波动；与之相对，承压含水层的测压水头面呈现降落漏斗形态，2004年至2014年间水头以1.6 m/年的速率持续下降。该系统的排泄项包括地下水开采量（48.42×10^6 m³/年）、地下水向地表水的排泄量（6.33×10^6 m³/年）以及入海排泄量（18.50×10^6 m³/年）；补给项则包括灌溉回渗量（34.67×10^6 m³/年）与皮乌拉上层含水层（Higher Piura Aquifer）的侧向补给量（27.23×10^6 m³/年）。研究区存在11.24×10^6 m³/年的水量失衡，该部分差额由含水层储水量消耗补充，进而引发水头下降与径流格局改变，揭示了该含水层系统正面临显著不可持续的过度开采问题，且该问题对承压含水层的影响更为突出。本模型的分析结果为厘清该区域水文过程提供了理论依据，同时可为缓解当前含水层困境提出优化策略提供支撑。