Deforestation, Land use Change and Groundwater Quality in Peri-Urban of Ibadan Zone, Southwestern Nigeria: A case Study of Ido Local Government Area

Deforestation and changes in land use and land cover (LULC) can significantly affect groundwater quality in peri-urban areas. However, the relationships between vegetation loss, groundwater quality remain insufficiently documented in southwestern Nigeria. This study examined LULC changes and their implications groundwater quality in the Ido Local Government Area (LGA), Ibadan, Southwestern Nigeria. Multi-temporal Landsat imagery covering 2005-2025 and the Normalized Difference Vegetation Index (NDVI) were used to analyze changes in vegetation and land cover. Forty groundwater samples were collected from four land-use types: built-up areas, sparse vegetation, shrubs/grassland, and dense vegetation, with ten samples from each land-use types. Physicochemical parameters and heavy metals were analysed using standard methods. Descriptive statistics, One-way analysis of variance (ANOVA), Tukey's HSD tests, Heavy Metal Pollution Index (HPI), and Heavy Metal Evaluation Index (HEI) were employed to evaluate different in groundwater quality across the land-use types. Results indicated a significant decrease in dense vegetation cover, dropping from 57.47% in 2005 to 4.74% in 2025, representing a reduction of about 91.8% while built-up areas lingering from 4.44% to 23.60%. Groundwater in built-up areas showed highest nitrate concentrations (17.19 ± 0.70 mg/L), electrical conductivity (473.87± 9.05 µS/cm), lead (0.02 mg/L) and cadmium (0.003) while those from densely vegetated areas recorded lower nitrate and lead concentrations of 0.003 mg/L and 0.002 mg/L respectively. Statistical analysis indicated significant differences (p < 0.05) among land-use types. HPI values range from 53.77 in densely vegetated areas to 115.57 in built-up zones, while HEI values rise from 1.56 to 5.08, indicating low to high contamination. This study highlights the relationship vegetation loss, urbanization and deteriorating groundwater quality. Forest restoration, regular groundwater monitoring and sustainable land-use planning are recommended for protection of groundwater resources.