Author :
Adama GASSAMA-JALLOW
In this research, the hydrochemistry of the GBA basin were assessed for 118 wells/boreholes which identified three major water-types groups: i) bicarbonate (m-HCO3, Ca-HCO3, and Na-HCO3) facies, ii) chloride (Na-Cl and m-Cl) facies, iii) sulphate (Ca-SO4) facies and iv) mixed (m-m and Na-m) facies. It was detected that 23% of samples have high concentration of NO3. Modeling of groundwater dynamics was conducted using recharge estimated by the Thornthwaite model to simulate the impacts of climate change on groundwater heads trend over the 2006-2050 period using RCP4.5 and RCP8.5 scenarios. A decreasing groundwater recharge trend and groundwater head was observed. Annual groundwater recharge decreases by 5% during the period 2006-2020 and by 8% during the period 2030-2060. The decrease in head over time with RCP8.5 has a growth rate estimated at -14%.