Hydrochemical peculiarities and groundwater quality assessment of the Birimian and Tarkwaian aquifer systems in Bosome Freho District and Bekwai Municipality of the Ashanti Region, Ghana

Louis Boansi Okofo,Ekua Afrakoma Armoo,Kenneth Bedu-Addo,Nana Akyerefi Anderson

doi:10.1007/s12665-021-10081-2

Abstract

The Birimian and Tarkwaian aquifer systems are the main sources of water supply for the Bosome Freho District and Bekwai Municipality inhabitants in the Ashanti region of Ghana. A hydrogeochemical assessment was carried out to ascertain the natural baseline chemistry of the groundwaters and the factors influencing groundwater chemistry in these two areas. A multivariate statistical tool consisting of principal component analysis (PCA) and hierarchical cluster analysis (HCA) together with hydrochemical graphical plots was applied on 64 groundwater samples. The Q–mode HCA results were used to explain the changes in groundwater chemistry along the flow paths where three spatial groundwater zones and water types were delineated. The first type consists of Ca–Mg–HCO3 freshwater (recharge zone), which transitions into Ca–Na–HCO3 or Na–Ca–HCO3 mixed waters (intermediate zone) and finally evolves to the third type of Na–Ca–Mg–HCO3–Cl water (discharge zone). The study also reveals that the natural process influencing water chemistry is groundwater–rock interaction from carbonate and silicate weathering/dissolution, aided by carbonic acid from precipitation and releases concentration of Na+, Ca2+, Mg2+, and HCO3− into the groundwaters significantly. The chloro-alkaline indices also reveal cation exchange as the principal natural factor that controls groundwater chemistry in the area. Inverse geochemical modelling shows the dissolution of primary minerals such as dolomite, plagioclase, halite, gypsum, and precipitation of calcite and chlorite along the groundwater flow path. Anthropogenic activities have little influence on groundwater chemistry. The quality of groundwater in the Bosome Freho District and Bekwai Municipality is suitable for irrigational use and drinking water consumption. The results obtained so far will contribute to research paucity in the study area and serve as a guide for decision-makers for improved water resources management.

Highlights

Increasing urbanisation as a result of rapid population growth in most African cities imposes a tremendous challenge on the available and future water resources
The most ambitious is the formulation of United Nations Sustainable Development Goals 6 (SDGs) as a stand-alone goal to ensure that clean water use and sanitation practice become basic and universal to humanity
The results indicated that low acidic groundwater and silicate weathering are the main natural factors controlling groundwater chemistry in the area

Summary

Introduction

Increasing urbanisation as a result of rapid population growth in most African cities imposes a tremendous challenge on the available and future water resources. Since the year 2000, when the majority of the world's population became urbanised, a gamut of international, regional, local, government, and non-governmental organisations spearheaded by the United Nations have dedicated strengths and resources to examining how sustainable water could be provided in the wake of the global climatic changes and increasing population, especially in developing countries (Cobbinah et al 2016). In recent years, there has been a mismatch between water supply and demand in urban cities of Ghana as a result of increasing population demand. With the increasing call for wider water coverage and distribution due to growing population demand, the water supply in the future remains uncertain (Cobbinah et al 2016; Adimalla 2020a, 2021)

Methods

Results

Conclusion