Hydrogeochemical and isotopic assessment for characterizing groundwater quality and recharge processes in the Lower Anayari catchment of the Upper East Region, Ghana

Abstract

The Lower Anayari Catchment (LAC) groundwater system of the upper east region contributes substantially to the populace’s socioeconomic development. LAC is well distinguished for intense farming activities. This study sought to assess the quality and processes/activities that impact on the groundwater chemistry in the catchment. Forty-one (41) samples, comprising boreholes and hand-dug wells were sampled from six (6) prime communities (Kulwase, Manyoro, Mirigu, Nakolo, Paga and Pungu) for physico-chemical and stable isotopes analysis. Hydrochemistry, ionic ratios, principal component analysis (PCA), geostatistics and stable isotopes (δ18O and δ2H) approaches were applied to construe the hydrogeochemistry of the groundwater system. Utilizing PCA and geostatistics, two factors controlling groundwater quality were depicted as; (a) V1- the dissolution of silicate minerals and (b) V2- agrochemicals/domestic waste. Piper Trilinear plot identified two hydrochemical facies, namely, Ca-Na-HCO3 and Na-Ca-HCO3. Cation exchange processes and silicate weathering/dissolutions are main drivers of the groundwater chemistry. Stable isotopes suggests groundwater in LAC is mainly of meteoric origin and a well-mixed system. However, few deviations of groundwater isotopic signatures from GMWL were observed suggesting evaporation before recharge or recharge occurring from an enriched source.