Groundwater vulnerability mapping and health risk assessment of essential elements deficiencies in groundwater in the Lukunga watershed of Kinshasa city

Auteur(s): Matungila Juve Juvenal, Hallal Dahbia Djoudar, Ouahiba Aziez, Tshimanga Raphael, Makanzu Fils, Nzau Umba-di-Mbudi Clément
Nom de la revue/Journal: Geomatics, Landmanegment and landscape (GLL)
Mois: octobre
Année: 2025

Résumé

The increasing reliance on boreholes in Kinshasa reflects the persistent inadequacy of public water supply, raising concerns about groundwater management and potential health risks from aquifer contamination. This study assesses groundwater vulnerability in the Lukunga watershed using the GOD method, complemented by a health risk analysis focused on deficiencies in essential minerals—calcium (Ca) and magnesium (Mg). The Health Risk Quotient (HQd) was applied to evaluate chronic exposure risks. Physico-chemical data from 23 water samples (September 2023) supported the generation and validation of vulnerability maps. The integration of the GOD model and HQd approach offers a cost-effective and scientifically robust framework, especially suited for datalimited urban settings. The GOD model provided a rapid classification of aquifer sensitivity, while HQd refinement incorporated hydrochemical data to improve exposure risk estimates. Results revealed that nearly 30% of the watershed falls under "Very High" vulnerability, particularly in downstream areas and along major rivers. The main source of pollution is linked to domestic waste due to poor urban sanitation. Although chemical contamination remains low, the predominant health risk arises from insufficient Ca and Mg levels, with average concentrations of 1.19 mg/L and 1.07 mg/L, respectively. These correspond to very soft water and insufficient daily intake, especially for vulnerable populations. The elevated HQd values indicate potential long-term health consequences, including risks for bone and cardiovascular conditions. This study highlights the urgent need for improved groundwater monitoring and mineral supplementation strategies to protect public health and ensure sustainable water resource management in Kinshasa.