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.