DOI – https://doi.org/10.46793/Vodoprivreda57.5-6.187PK
Key words – Northen Togo, Savanne area, contact water-rocks, minerals dissolutions, hydrogeochemical facies
ABSTRACT
In response to challenges related to drinking water quality in the Savane region of northern Togo, a detailed hydrogeochemical study was conducted to address the growing demand for safe groundwater. The study focused on analysing the major cations and anions that define the hydrogeochemical signature of the water. An initial assessment of mineralisation processes indicated that water–rock interaction is the dominant mechanism influencing groundwater chemistry. Analysis of water hardness showed that most samples fall within the “slightly hard” category. These elements are derived from the dissolution of certain silicate minerals such as plagioclases (abite, anorthite, etc.), micas and certain clay minerals (illite, kaolinite, smectite, etc.). Using the Piper diagram, the different water types were identified and linked to the lithology of their respective aquifers. Among others, we can mention: Bicarbonate–calcium–magnesium facies in basement aquifers, Bicarbonate–sodium–potassium facies for claystone, silexite, and carbonate formations, Bicarbonate–chloride–potassium/sodium facies in sandstone units, Bicarbonate–calcium–sodium facies for alluvial deposits.
Spatial distribution maps of the major ions were also generated, highlighting zones of predominance for each ion. The spatial distribution maps revealed a predominance of magnesium and silica in groundwater from basement formations, whereas Na+, Ca2+, Cl–, HCO₃⁻ and SO₄²⁻ ions are more dominant in groundwater originating from other geological units. Finally, an evaluation of water potability based on WQI for consumptions purpose assigns a good quality (WQI=24.49) to all waters in the area. For irrigation purpose, sodium percentage and alkalinity power showed that most groundwater samples are of excellent quality, with only a few exceptions.
Autori: Eugène PYABALO KATANSAO, Kodjovi ZONDOKPO, Ljiljana VASIĆ, Saša MILANOVIĆ, Jean TOUGOMA
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