Kebreab Ghebremichael

Multivariate statistical analysis for fluoride occurrence in groundwater in the Northern region of Ghana.

The presence of excess fluoride in groundwater in the Northern region of Ghana has resulted in the closure of many boreholes for drinking water supply to avoid the incidence of fluorosis and other related health effects. The fluoride concentration in 357 groundwater samples from the area ranged between 0.0 and 11.6mg/L, with a mean value of 1.13mg/L. Piper graphical classification, correlation coefficients, principal component analysis (PCA) and thermodynamic calculations were used as an approach to gain insight into the groundwater chemical composition and to help understand the dominant mechanisms influencing the occurrence of high fluoride waters. Spatial join procedure was used to examine the relationship between the underlying geology of the study area and fluoride distribution. Six groundwater types were identified for the area: Ca-Mg-HCO(3), Ca-Mg-SO(4), Na-Cl, Na-SO(4), Na-HCO(3) and mixed water type. PCA performed on the groundwater chemical data resulted in 4 principal components (PCs) explaining 72% of the data variance. The PCs represented the predominant processes controlling the groundwater chemistry in the study area which include; mineral dissolution reactions, ion exchange processes and evapotranspiration processes. PHREEQC calculations for saturation indices for the groundwater samples indicated they were largely saturated with respect to calcite and under-saturated with respect to fluorite, suggesting that dissolution of fluorite may be occurring in the areas where it is present. A review of the PCA results and an evaluation of the equilibrium state of the groundwater based on the saturation indices, suggest that some of the processes controlling the overall groundwater chemistry in the study area also influenced the fluoride enrichment. These predominant processes include the dissolution of the mineral fluorite, anion exchange processes (F(-)/OH(-)) involving clay minerals and evapotranspiration processes. Elevated fluoride levels in the study area were found to occur predominantly in the Saboba and Cheriponi districts and also in the Yendi, Nanumba North and South districts. These areas are underlain by the Middle Voltain formation (Obossom and Oti beds), comprising mainly of sandstone, limestone, conglomerate, shale, arkose and mudstone. Results of the hydrochemical analysis show that aside from the boreholes with elevated concentrations of fluoride (beyond 1.5mg/L), groundwater in the study area based on the parameters analyzed is generally chemically acceptable and suitable for domestic use.

A Paradigm Shift in Urban Water Management: An Imperative to Achieve Sustainability

With increasing global change pressures (such as urbanization and climate change) and existing unsustainable factors and risks inherent to conventional urban water management, cities in the future will experience difficulties in efficiently managing scarcer and less reliable water resources. In order to meet these challenges, there needs to be a paradigm shift to integrated urban water management (IUWM). This paradigm shift is based on several key concepts including resilience of urban water systems to global change pressures, interventions over the entire urban water cycle, reconsideration of the way water is used (and reused), and greater application of natural systems for treatment. This chapter will present an integrated framework supporting IUWM and its key principles.