wcm.03.2025.603.610

Groundwater is vital for socio-economic development worldwide, as it sustains communities and supports various industries. Indonesia, especially the island of Java, has a unique geological setting, characterized by a volcanic aquifer associated with andesitic stratovolcanoes, which contributes to the availability of highquality groundwater. However, groundwater in volcanic terrains is often complex and unidentified due to heterogeneous subsurface conditions, particularly in regions experiencing water scarcity and environmental degradation. This study employed Electrical Resistivity Tomography (ERT) using the ADMT 300HT2 to characterize aquifers in seven villages of Probolinggo Regency, East Java. The research encompasses seven
villages: Maron Kidul, Wonorejo, Sumberan, Brumbungan Kidul, Jangur, Tegasan Kidul, and Alas Tengah. The results revealed resistivity values ranging from 0.3 to 60 Ωm, with low values (<5 Ωm) indicating clay-rich impermeable layers and higher values (>30 Ωm) corresponding to productive aquifers such as volcanic sandstone, sandy breccia, and silt sand. Aquifers were identified at depths of 20–50 m (unconfined) and >100 m (confined), with the highest potential observed in Wonorejo, Sumberan, and Tegasan Kidul villages. These findings provide crucial insights for local government authorities, offering hydrogeologically based recommendations for optimal drilling sites and facilitating the development of sustainable groundwater management strategies in Probolinggo Regency.