Caractérisation hydrodynamique et hydrogéochimique du bassin versant de Badombé, Est- Cameroun

Abstract

Major metropolises around the world, and those in Cameroon in particular, are facing increasing pressures that are impacting the quantity and quality of water resources. This study was initiated to analyze the hydrodynamic functioning and groundwater quality of the Badombé watershed, located in eastern Cameroon. The methodology adopted includes bibliographic and cartographic research, field investigations (piezometric monitoring, physico-chemical parameter measurements, water sampling in 2022) and laboratory analyses (physico-chemical and bacteriological characterization, data processing using statistical, hydrochemical and GIS tools). Hydrodynamically, the results show that piezometric levels in the 48 wells monitored vary from 623.6 m in the rainy season to 664.5 m in the dry season. Piezometric fluctuations range from 0.39 m (well 19) to 3.56 m (well 14). These limited variations can be explained by the clay-sand nature of the soils in the unsaturated zone, characterized by low permeability, and by the extent of runoff, reducing infiltration. Physico-chemically, the water has a temperature of between 22.4°C and 22.5°C, a pH ranging from 3.4 to 9.7 (acid to basic), and relatively low to high mineralization (58.3 µS/cm ≤ CE ≤ 857 µS/cm). Two main hydrochemical facies have been identified: chloride-sodium-potassium facies and bicarbonate-sodium-potassium facies. Although the majority of physico-chemical parameters comply with WHO and ANOR standards, some nitrate and ammonium concentrations indicate pollution from certain structures. Groundwater in the Badombé watershed therefore requires prior treatment before it can be used for human consumption. The vulnerability of water resources in this area is accentuated by the shallowness of the aquifers, their geographical location, socio-economic activities (agriculture and livestock farming), and the inadequacy of sanitation infrastructures (latrines, liquid and solid waste disposal).