Characterization of groundwater in southwest Ghana: Implications for sustainable agriculture and safe water supply in a mining-dominated zone

Abstract

Illegal mining activities locally known as galamsey have polluted many rivers in Ghana, particularly the southwestern part of the country. This has tremendously increased the operational cost of the treatment of surface water for public consumption, threatening access to potable water. As a result, many people have now resorted to the utilization of groundwater resources for domestic and small-scale irrigation. It is therefore imperative to be proactive in establishing the background groundwater quality status to advise or not on their usage to augment the surface water utilization in the area. This study investigated the water quality of groundwater from mining and non-mining areas in the Wassa area for human consumption, irrigation, and livestock rearing. A total of 150 groundwater samples were collected for 16 analytical assessments. The results indicate slightly acidic groundwater sources with pH values ranging from 5.85 to 8.61. About 33 % of the samples were acidic. Total dissolved solids (TDS) ranged from 23.41 to 463.0 mg/L. Na+ levels varied between 2.3 mg/L and 45.94 mg/L, whereas Ca2+ and Mg2+ concentrations were 0.40–68.38 mg/L and 4.95–22.91 mg/L, respectively. NO3− concentrations fluctuated from 0.0 mg/L to 102.95 mg/L, and Cl− levels fell between 0.61 mg/L and 115.20 mg/L. The water quality index analysis showed that 61 % of the groundwater samples are of optimal quality for domestic usage. The hydrogeochemical facies analysis suggested that the groundwater chemistry was primarily influenced by rock weathering and dissolution processes. Based on the Sodium Absorption Ratio (SAR), Percentage sodium (Na %), Residual sodium Carbonate (RSBC), Kelly's Ratio (KR), and Magnesium Hazard (MH) assessment, 88 %, 9 %, 1 %, 61 %, and 77 % of the samples were excellent for irrigation. The evaluation of the groundwater showed that a majority of the sources were not entirely suitable for domestic and irrigation purposes.

Keywords

• Groundwater quality
• Irrigation suitability
• Domestic use
• Food security
• Mining-dominated areas