Assessing Shallow Groundwater Depth and Electrical Conductivity in the Brazilian Semiarid: A Geostatistical Analysis

The Brazilian semiarid region faces water scarcity, with alluvial aquifers playing a crucial role in agricultural water security. This study assesses the spatiotemporal variability of groundwater quantity and salinity, analyzing natural and anthropogenic impacts, including post-pandemic trends. The investigation was developed in the Mimoso Alluvial Valley (MAV), Pernambuco State, mainly used for communal irrigation supply. The spatiotemporal dynamics of land use (LUC) was performed based on data provided by Mapbiomas for the years 2012, 2016, 2019, and 2023. Geostatistical analysis was applied for mapping water table levels and salinity. Changes in LUC suggest possible forest regeneration influenced by climatic factors and anthropogenic pressure alleviation. Electrical conductivity (EC) and groundwater level (GWL) exhibited medium to high variability. Temporal trends highlight climatic influences, groundwater abstraction, and recharge/discharge dynamics. Pre-2019 years were classified as dry, whereas the 2019–2023 years ranged from rainy to extremely rainy, leading to lower EC and GWL variability in 2023. Additionally, the COVID-19 pandemic temporarily reduced agriculture, lowering salinity and aiding groundwater recovery. The spatial analysis revealed critical distribution patterns, highlighting the interaction between natural processes and human activities. These findings provide valuable insights for optimizing irrigation and environmental strategies, supporting long-term groundwater sustainability in semiarid regions.