Knowledge of stable isotopes and chemical tracers in meteoric water has been used as a valuable tool in various environmental studies. A systematic monthly sampling of precipitation, in the Ndop plain, was carried out to generate basic data on δ 18 , δD and Cl-, determine their seasonal variations and controlling factors to be used as baseline data in hydrological and climatological studies. The δ 18 O-δD relationship of rainfall gives a regression line: δD = 7.93 δ 18 O + 13.26 (R 2 = 0.99), which represents the Ndop Meteoric Water Line (NMWL). The slope is similar to the Global Meteoric Water Line (GMWL), but, with a high d-excess, which suggests a contribution of continental recycled moisture to precipitation. Precipitation shows a wide variation, throughout the year (2012) in δ 18 O and δD, from +3.86 and +38.62 ‰ in January to-7.98 and-53.18 ‰ in September, respectively. The volume-weighted mean of precipitation, which plots close to June rainfall, is-5.61 ‰

This study was conducted on the hydrochemistry of shallow groundwater and surface water in the Ndop plain, North West Cameroon. The objectives were to determine the physico-chemical characteristics of water, controls on water chemistry and suitability for drinking and irrigation. Forty-six shallow groundwater and 26 surface water samples were investigated. Field measurements of physical parameters were preceded by chemical analyses of the samples for major ions and F-. About 69% of the water sources had pH values below 6.5, classifying the water as barely acidic. Electrical conductivity (<282 µS/cm) and total dissolved solids (<183 mg/l) were low suggesting low-mineralised and freshwater. The relative abundance of major ions (meq/l) was Na 2+ >Ca 2+ >Mg 2+ >K + for cations and HCO 3->>NO 3-≥Cl->SO 4 2for anions. Major ion concentrations were low, and within the WHO guidelines for drinking water, but Fconcentrations were much lower (<0.39 mg/l) and below guideline value. Main water types and proportions were Na-HCO 3 (53 %), Ca-HCO 3 (35 %) and a mixed Na-Ca-HCO 3 (11%). Predominant processes influencing water chemistry were incongruent dissolution of silicate minerals and cation-exchange of Na + in rocks for Ca 2+ in water. The low major ion concentrations indicated low water-rock interactions and short residence time. The analysed water was suitable for irrigation.

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