In this study, we develop a methodology to quantitatively integrate well resistivity logs and audio-magnetotelluric (AMT) sounding in the context of groundwater investigations. The experiments were conducted in a complex Quaternary depositional environment within a region of intensive groundwater use. A synthetic resistivity model was constructed from well resistivity log data and used for forward modelling to generate synthetic AMT responses, which were then inverted using Occam’s algorithm. The AMT-derived resistivity model was subsequently compared with the model obtained from the inversion of the field AMT sounding using the Pearson correlation coefficient (r) and the root mean square error (RMSE). A scalar shift factor (k) was introduced to optimize the match between both models. The comparison between the AMT-derived resistivity model and the well resistivity logs yielded a Pearson correlation coefficient of 0.669 and an RMSE of 0.1911. The optimal scalar shift factor was k = 1.1854, with a 95% confidence interval of [1.1470, 1.2246], indicating only a minor discrepancy. These results demonstrate that AMT can successfully recover a resistivity structure consistent with well resistivity logs. The proposed quantitative integration and validation workflow provides a robust framework to reduce the inherent ambiguity in AMT interpretation and highlights its potential as a direct hydrogeophysical tool for groundwater studies.

Groundwater is one of the main sources of water supply in tropical developing countries; however, its integrated management is often constrained by limited hydrogeological information and increasing anthropogenic pressures on aquifer systems. This study presents the numerical modeling of groundwater flow in the Neogene–Quaternary aquifer system of the Middle Magdalena Valley (Colombia), focusing on the rural area of Puerto Wilches, which is characterized by strong surface–groundwater interactions, particularly with the Yarirí wetland and the Magdalena River. A three-dimensional model was implemented and calibrated in FEFLOW v.8.1 under steady-state and transient conditions, integrating both primary and secondary data. The dataset included piezometric levels measured with water level meters and automatic loggers, hydrometeorological records, 21 physicochemical and microbiological parameters analyzed in 45 samples collected during three field campaigns under contrasting hydrological conditions, 79 pumping tests, detailed lithological columns from drilled wells, and complementary geological and geophysical models. The results indicate a predominant east–west groundwater flow from the Eastern Cordillera toward the Magdalena River, with seasonal recharge and discharge patterns controlled by the bimodal rainfall regime. Microbiological contamination (total coliforms in 69% of groundwater samples) and nitrate concentrations above 10 mg/L in 21% of wells were detected, mainly due to agricultural fertilizers and domestic wastewater infiltration. Particle tracking revealed predominantly horizontal flow paths, with transit times of up to 800 years in intermediate units of the Real Group and around 60 years in shallow Quaternary deposits, highlighting the differential vulnerability of the system to contamination. These findings provide scientific foundations for strengthening integrated groundwater management in tropical regions under agroindustrial and hydrocarbon pressures and emphasize the need to consolidate monitoring networks, promote sustainable agricultural practices, and establish preventive measures to protect groundwater quality.

Understanding groundwater recharge patterns is essential for managing water resources in regions facing climate variability and increasing water use pressure. In this study, stable isotopes of Deuterium (2H) and Oxygen-18 (18O) are used as tracers to explore recharge dynamics and surface groundwater interactions in the Bogotá River basin. Using meteorological, geospatial, and isotopic data, the Isocompy library was applied to model the spatial distribution of the isotopic composition of precipitation, resulting in the first local-scale isoscape developed for the basin. The precipitation isoscape revealed a clear spatial variability associated with precipitation levels, recycled moisture, and topographic effects. By comparing this isoscape against the isotopic composition of groundwater, distinct recharge patterns and degrees of aquifer exploitation were identified across the basin. These findings highlight the value of isotopic tools and precipitation isoscapes in identifying recharge zones, understanding hydrological connectivity, and informing sustainable groundwater management. Continuous sampling and improved spatial resolution in isotopic models are recommended to better capture the complexity of recharge processes in heterogeneous basins such as that of the Bogotá River.