Numerical simulation of the protection perimeters of groundwater catchment structures in crystalline bedrock environment: Case of the Babo watershed (Central-Western Côte d′Ivoire)

Babo watershed (Central-Western Côte d′Ivoire) The fractured aquifers of the Babo watershed have enormous groundwater potential. This resource is used to supply drinking water to populations in rural areas and could help alleviate shortages observed in urban areas. However, the quality of these resources remains threatened due to the area's often high vulnerability to pollution. This study aims to develop a groundwater protection model for the Babo watershed, to define the perimeters and protection areas of the catchment structures. The methodology adopted is based on four stages: identification of potential groundwater storage zones; development of a hydrogeological model of the fractured aquifer; development of a numerical groundwater model flow; and simulation of protection perimeters based on the inverse trajectories of groundwater in the Babo watershed. The results obtained show that the area is favorable for the realization of high-yield boreholes, with a yield of 25 m 3 /h obtained at Ketro-Bassam, and the protection perimeters drawn up for these boreholes have an elliptical shape, with the longest axis corresponding to the direction of flow. These simulated perimeters vary from 1970 to 4300 m for the close protection perimeters (CPP) and from 5760 to 9500 m for the remote protection perimeters (RPP). The areas of these perimeters are between 0.3 and 3 km² for close protection perimeters (CPP) and 2–11 km² for remote protection perimeters (RPP). In this area, where groundwater is the only drinking water source, controlling potential contamination sources within the perimeters developed for these catchment points will contribute to preserving the quality and sustainable management of groundwater in the region. • The Babo watershed does not have a digital tool for groundwater protection. • This study is the first of its kind in a bedrock area in Côte d′Ivoire. • It enables the development of a digital groundwater flow model calibrated and validated with the Feflow code. • Define protection perimeters for certain boreholes in areas with high groundwater potential. • It helps prevent future pollution of this essential resource for the population of this area and ensures its sustainable management.