Groundwater quality status in the Division of Fitri (Chad)

In the Sahel region, groundwater is the main resource used for drinking and irrigation purposes. However, pressure from human activities poses several threats to this resource. The water quality of the Division of Fitri (Chad), is particularly concerned. The study, therefore, investigates the shallow water chemistry of this region by using major ions chemistry and water quality index. Firstly, result from piezometric analysis shows a recharge area in the north-eastern part of the division. Groundwater flows towards the lake where the aquifer becomes semi-confined to confined. In situ parameters revealed a dominance of neutral pH (7.2–8.01) due to a mixing of water circulation from silicate and evaporitic rocks. The mineralization increases significantly with depth due to borehole tapping gypsum while silicate rocks are associated mainly with the superficial formations. The facies CaMg-SO₄ is the most important related to the dissolution of gypsum minerals. An influence of anthropogenic activities on groundwater is also reflected by some higher concentrations in NO₃⁻ (up to 160 mg/l) which is partially correlated with Cl⁻ indicating a consequence of poor sanitation systems in the study region. Whilst Irrigation Water Quality Index suggest “No restriction’ for irrigation, Drinking Water Quality Index (DWQI) clearly shows that “poor” to “unsuitable” samples are located in the south of the Division where population is few. On the other hand, “Excellent” and “Good” water samples for drinking are observed in the north where human activities are less developed. This is evidence of the negative impacts that human can have on groundwater quality in rural areas thus, efforts must be carried out by stakeholders to protect the resource.