Hydrogeochemical and Groundwater Quality Studies in the High Bandama Watershed at Tortiya (Northern of Côte d’Ivoire)

摘要

Hydrochemical and groundwater quality of High Bandama watershed were investigated through thirty-five (35) samples composed of boreholes, hand pump wells and traditional wells. The analysis of physico-chemical parameters shows that groundwater is acidic with pH ranges from 3.2 to 6.9 and mean of 5.4. Electrical conductivity (EC) values were generally low and minimum and maximum were respectively 77 μS/cm and 553 μS/cm with an average of 250.3 μS/cm. Major cations (Ca~(2+), Mg~(2+), Na~(+) and K~(+)) were also generally low. Ca~(2+) and Mg~(2+) are being the most dominants cations with concentration values ranges from 4 - 56 mg/l and 0 - 55 mg/l respectively with mean value of 18.11 and 15.31 mg/l. HCO_(3)~(?) is the most dominant anion with minimum and maximum values ranging from 5 to 215 mg/l. According to WHO guidelines, groundwater quality is good for drinking. Piper diagram classified the hydrogeochemical facies into Ca-HCO_(3) (48.57%), Ca-Mg-HCO_(3) (31.43%), Ca-Mg-Cl (17.14%) and Na-Cl (2.86%) water type with one sample for Na-Cl. Compositional relation with plot of Ca + Mg versus HCO_(3 ) + SO_(4) and Chloro Alkaline Indice (CAI) confirms that the majority of groundwater samples (66.67%) exchange their ions Ca and Mg with Na and K from aquifer materials. Gibbs diagram showed that the rock-water interaction or weathering is the dominant process responsible of water chemistry.