Assessment of groundwater rise zones using electrical resistivity for foundation stability analysis

Poor drainage conditions can lead to soil erosion and water infiltration, potentially compromising the stability of nearby buildings. This study aims to identify and characterize zones of rising groundwater at a construction site in southeastern Bangui, Central African Republic. The objective is to evaluate the potential impact of these zones on foundation stability and to guide the design of effective drainage systems. Electrical resistivity tomography (ERT) was employed as the primary investigative method, using a Schlumberger array with 2-meter electrode spacing. This geophysical technique was selected due to its proven effectiveness in delineating subsurface structures and assessing groundwater flow patterns in complex geological settings. The ERT survey revealed three distinct layers: (i) weathered bedrock (236–750 Ω·m); (ii) fissured bedrock (750–2,400 Ω·m); and (iii) fresh bedrock (> 2,400 Ω·m). Zones of low resistivity (less than 236 Ω·m) indicated saturated areas likely associated with groundwater accumulation. Two aquifer systems were identified: a shallow weathered bedrock aquifer (2–4 m deep) and a deeper fissured aquifer. The shallow aquifers extend laterally 3–10 m, with a water table depth of 1.5–3 m. They lack hydraulic connectivity with the deeper system, which likely contributes to the observed rise in groundwater levels. These findings underscore the importance of detailed hydrogeophysical surveys in construction planning. Rising groundwater, resulting from isolated aquifer systems, can threaten the structural integrity of foundations. The results inform the design of more resilient drainage infrastructure and highlight the need for ongoing hydrogeological monitoring, particularly of piezometric levels and flow dynamics, to ensure the site’s long-term . ✓ Electrical resistivity tomography reveals hidden groundwater risks at construction sites. ✓ Two disconnected aquifers can contribute to rising groundwater levels, which can impact the stability of infrastructure. ✓ A multi-layered aquifer system influences drainage system design and soil behavior.