Delineation of Recharge Zones for Sustainable Protection of Groundwater in Bidou I (South Cameroon)

Abstract

The aim of this work is to delineate groundwater recharge potential zones in Bidou I, covering approximately a surface area of 144 km2. To meet this goal, seven influencing parameters were merged in a GIS. A total of 2370 Lineaments have been extracted and mapped using remote sensing and GIS technics. Their lengths vary between 60 and 4498 m with an average of 525 ± 420 m. Eight deformed rock types and two major fractures cross-cutting each other were identified. The mapped lineaments main directions (N330°N–045°E) define the groundwater flowing direction corresponding to the recharge average direction (N010°E) of the aquifers in the area. The water balance calculation shows that about 10% of the average interannual rainfall in the Kribi region (1991–2021) was effectively infiltrated. This implies that the effective recharge feeds the stock variation (ΔRi). The calculated rock filtration velocities range from 0.5 × 10−9 to 11.0 × 10−9 m/s with an average of 2.5 × 10−9 m/s. The LULC classes expressed as percentages of the total study area are: Vegetation: 90%, Water bodies: 5%, Bare soils: 4% and Built-up: 1%. In prelude to sustainable groundwater protection and management in the area, a five classes map (very poor, poor, moderate, good and very good) of Groundwater Recharge Potential Zones (GWRPZ) was realized by assigning to each layer a fixed weight and a score from Analytical Hierarchy Process (AHP) using weighted overlay analysis (WOA) tool.