Assessment of Infiltration Characteristics and Groundwater Recharge Potentials under Different Land-use Practices in a Tropical Watershed, a Case Study of Otamiri-Nworie River, Imo State, Nigeria

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This study assessed soil infiltration characteristics and groundwater recharge potential under four land-use practices—Agricultural Land, Built-up Area, Forest Reserve, and Bare Soil—within the Otamiri–Nworie tropical watershed in Owerri Municipal, Imo State, southeastern Nigeria. Field infiltration measurements were obtained using a double-ring infiltrometer, while soil samples were analysed for selected physical properties. The Horton, Philip, and Kostiakov models were fitted to the measured infiltration data, and groundwater recharge potential was estimated using a water-balance approach. Steady-state infiltration rates differed among the land-use types, with the Forest Reserve recording the highest value (184.5 mm/hr), followed by Agricultural Land (112.3 mm/hr), Bare Soil (45.2 mm/hr), and the Built-up Area (12.1 mm/hr). Saturated hydraulic conductivity followed a similar pattern, ranging from 9.64 cm/hr in the Forest Reserve to 2.07 cm/hr in the Built-up Area. The Horton model produced the strongest fit across the evaluated land uses, with coefficients of determination ranging from 0.94 to 0.97 and the lowest root mean square errors among the tested models. Groundwater recharge estimates also indicated higher recharge under forested conditions and lower recharge in the Built-up Area. The results indicate that land-use practices are associated with marked differences in infiltration, soil hydraulic behaviour, and groundwater recharge potential within the watershed.

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