High-resolution hydrological modeling to assess groundwater recharge dynamics in the Colombian Orinoco

Reliable estimation of Natural Groundwater Recharge (NGR) in tropical regions is challenging due to highly variable hydrologic conditions and limited ground data. We studied the Vichada River in the Colombian Orinoco, a tropical region characterized by permeable soils, humid climate, and hydroclimatic seasonality driven by the Orinoco Low-Level Jet and the Intertropical Convergence Zone. We proposed a distributed hydrological modeling framework to predict high-resolution NGR under data-scarce conditions, integrating the TETIS model with geostatistical methods and satellite-derived hydroclimatic products. CHIRPS precipitation and ERA-5 temperature data were statistically downscaled to 250 m spatial resolution, and geostatistical blending was used to correct the downscaled precipitation bias. These techniques enhanced precipitation accuracy and representation of hydrological process heterogeneity. The model was calibrated and validated in a hydrologically similar nearby basin (Manacacías River), achieving a Kling–Gupta Efficiency of 0.86. Simulated recharge exhibits a strong correlation with precipitation, with negligible lag, suggesting rapid infiltration in sandy soils and shallow aquifers. Groundwater recharge accounts for approximately 65 % of annual precipitation and shows no significant long-term trend. Spatially, higher recharge rates occur in flat, vegetated, sandy areas and persist during the dry seasons. These results highlight the aquifer’s capacity to buffer climatic variability. This study provides a transferable framework for high-resolution NGR estimation that supports groundwater management and climate adaptation in data-scarce environments and enhances understanding of recharge dynamics. • Estimation of natural groundwater recharge rates in the Colombian Orinoco. • High-resolution distributed hydrological model at 250 m and daily scale. • Novel downscaling–blending approach for high-resolution meteorological inputs. • Recharge persists during dry seasons, buffering climate variability effects. • Results support the feasibility of Managed Aquifer Recharge in Colombia.