Stochastic groundwater modeling of a sedimentary aquifer: evaluation of the impacts of abstraction scenarios under conditions of reduced recharge

A transient finite difference groundwater flow model has been calibrated for the Nasia sub-catchment of the White Volta Basin. This model has been validated through a stochastic parameter randomization process and used to evaluate the impacts of groundwater abstraction scenarios on resource sustainability in the basin. A total of 1500 equally likely model realizations of the same terrain based on 1500 equally likely combinations of the data of the key aquifer input parameters were calibrated and used for the scenario analysis. This was done to evaluate model non-uniqueness arising from uncertainties in the key aquifer parameters especially hydraulic conductivity and recharge by comparing the realizations and statistically determining the degree to which they differ from each other. Parameter standard deviations, computed from the calibrated data of the key parameters of hydraulic conductivity and recharge, were used as a yardstick for evaluating model non-uniqueness. All model realizations suggest horizontal hydraulic conductivity estimates in the range of 0.03–78.4 m/day, although over 70 % of the area has values in the range of 0.03–14 m/day. Low standard deviations of the horizontal hydraulic conductivity estimates from the 1500 solutions suggest that this range adequately reflects the properties of the material in the terrain. Lateral groundwater inflows and outflows appear to constitute significant components of the groundwater budgets in the terrain, although estimated direct vertical recharge from precipitation amounts to about 7 % of annual precipitation. High potential for groundwater development has been suggested in the simulations, corroborating earlier estimates of groundwater recharge. Simulation of groundwater abstraction scenarios suggests that the domain can sustain abstraction rates of up to 200 % of the current estimated abstraction rates of 12,960 m³/day under the current recharge rates. Decreasing groundwater recharge by 10 % over a 20-year period will not significantly alter the results of this abstraction scenario. However, increasing abstraction rates by 300 % over the period with decreasing recharge by 10 % will lead to drastic drawdowns in the hydraulic head over the entire terrain by up to 6 m and could cause reversals of flow in most parts of the terrain.     

Downstream effects of dams on livelihoods of river-dependent communities: the case of Ghana’s Kpong Dam

Construction of dams affects the livelihoods of the population living along the dammed river. There is a need for more studies to guide dam development policies and management to safeguard the livelihoods of local river users. This paper examines the effects of dams on the socio-economic livelihoods of downstream communities by drawing on the Kpong Dam in Ghana constructed from 1979 to 1982 with the goal of supplying energy and for irrigation purposes. Primary data were collected in resettled and non-resettled downstream communities using a mixed-research approach. This case study highlights how the Kpong Dam has affected the downstream river-dependent population whose livelihoods, particularly farming and fishing revolved around the seasonal flow regimes of the Volta River. Our study challenges the general perception that dams increase agricultural production by illustrating that developing ancillary facilities such as irrigation schemes as part of dam projects can enhance all-year-round agricultural production to improve food and income security of downstream households only when constraints such as lack of farm inputs are addressed. To safeguard livelihoods and limit the social impacts of dams, compensation schemes and alternative livelihood activities should be designed to include resettled and non-resettled communities along the downstream areas affected by dam projects.     

Adsorption phenomena in hydrometallurgy, 1 The uptake of copper,nickel and cobalt by oxide adsorbents in aqueous ammoniacal solutions

The uptake or adsorption of copper, nickel and cobalt by finely divided oxide solids in aqueous ammoniacal medium has been investigated experimentally in order to determine how adsorption on leach residues can affect the recovery of leachable metals. Hematite, rutile, alumina and quartz were used as model solid adsorbents. In the case of ammoniacal leach solutions the controlling metal species appears to be the aqueous neutral hydroxo species. Adsorption behavior was found to have maxima and minima as a function of pH, the magnitude of which depends on ammonia concentration, the metal cation, and the adsorbent.     

The Best of Times and the Worst of Times: Structural Adjustment Programs and Uneven Development in Africa: The Case Of Ghana

Since 1983, Ghana has been undergoing World Bank and International Monetary Fund (IMF) sponsored Structural Adjustment Programs (SAPs). The implementation of the SAPs, it is claimed, has arrested Ghana's economy from complete collapse, resulted in consistent growth in GDP averaging 6% over the past decade, reduced inflation levels, created budget surplus, and increased export earnings. Compared to the 1970s, these are the best of times indeed. But while these SAPs‐derived improvements in the national economy have been recorded at the macro level, the benefits at the micro level are a matter of considerable debate. This study revisits the issue of socioeconomic and spatial disparities that have characterized Ghana since colonial times, emphasizing the period from 1983 when Ghana's SAPs began. It examines current patterns of socioeconomic disparities with emphasis on the distribution of, and access to, health, education, basic services, and the like. The study focuses on urban‐rural as well as interregional disparities in the country.     

Identification of historic shifts in daily rainfall regime,Wenchi, Ghana

The characteristics of rainfall regime and its variability in the sub-humid region of mid-Ghana is analyzed using daily rainfall data from the Wenchi, 1950–2000. Prior research in the area, suggests that climatic variability occurs at lower frequencies than the typical ENSO signal and may be more closely related to noted shifts in global climatic patterns. Fifty-six possible starting dates encompassing the traditional growing season, extending from late January to early November, at 5 day increments, are used to define temporal units of varying lengths, variable temporal units (VTUs). Rainfall characteristics in each unit are described by two variables: total rainfall and number of rainy days. Given the widely noted global climatic shift in the 1970s and the results of regional analyses, the 50 year record is sub-divided into two 20 year periods, 1950–1969 (period 1) and 1980–2000 (period 2). The means and variances of the two variables in each VTU are compared to identify any times when the changes in rainfall characteristics are most noticeable within the rainfall regime between periods. Both variables yield results consistent with the main rainy season and the long dry season being relatively unchanged, however the short dry spell is becoming wetter and the minor rainy season (September/October) has become significantly drier and shorter. The observations are consistent with the general north–south erosion of the bi-modal regime in West African which is associated with the southward shift of the ITCZ and the monsoonal system. This phenomenon is believed to be ongoing for the last 10,000 years in step with the hypothesized shift of the perihelion into the boreal winter. The use of independent arbitrary starting dates and durations (VTU) advances the understanding of temporal variability of rainfall, at a scale appropriate to agricultural practices in the study area.     

Adsorption phenomena in hydrometallurgy, 2. Electrophoretic behavior of oxides in aqueous ammoniacal solutions of copper,nickel and cobalt

The electrophoretic mobilities of finely divided oxides in aqueous ammoniacal solutions of copper, nickel, and cobalt have been measured. The solids used were rutile, alumina, quartz, and hematite. The effects of pH, ammonia-ammonium concentration, and metal-ion concentration on the electrophoretic behavior were investigated. The experimental results indicate that oxide colloids may undergo as may as five charge reversals in aqueous ammoniacal solutions of hydrolyzable ammine-forming metal ions.     

Changing rainfall inputs in the Volta basin: implications for water sharing in Ghana

We present evidence from the analysis of gridded annual rainfall data that, increased variability and declining rainfall totals are the main cause of declining lake levels in the Volta basin above the Akosombo Dam. West Africa has undergone a period of diminished rainfall, punctuated by a series of severe droughts and marked by a shift in rainfall regime. As a result, lake levels behind the hydro-electric impoundment have fluctuated so widely at times that, power has had to be rationed. The trends in the spatial and temporal variability of annual rainfall in the riparian nations explain the low impoundment levels frequent in recent decades. The drying of Burkina Faso and Mali is particularly marked and synchronous to an apparent shift in the rainfall regime in Ghana towards a longer dry season and vanishing short dry spell, the effects which tend to negate each other. The various regional and temporal associations between El Niño-Southern Oscillation phenomenon (ENSO) are investigated as a possible cause of variation across the basin. The strengths of these associations and low frequency shifts suggest an unfortunate correspondence between national and climatological boundaries which may serve to heighten regional political tensions resulting from ENSO effects. Lack of re-investment in the Akosombo Dam as a result of management policies, political and pre-construction contractual agreements have all conspired in recent decades to make these hydro-climatological changes more devastating.     

What has Corruption Got to do with it? Understanding the Persistence of Rural-Urban and Inter-Regional Inequalities in Ghana and Zimbabwe

Inequalities are no respecter of countries, including the affluent ones. Nevertheless, these problems appear to prevail more in the developing countries, which have the dubious distinction of having the highest degrees of inequalities in the world. Inequalities exist between urban and rural areas, as well as between the various regions. This paper discusses inequalities in Ghana and Zimbabwe, emphasizing the rural–urban dichotomy. Using data from the Ghana Demographic and Health Surveys (GDHS) and the Zimbabwe Demographic and Health Surveys (ZDHS) conducted by the respective statistical authorities of both countries and Macro International, the paper analyses existing inequalities in both countries. The paper also attempts to elucidate and understand the causes. It concludes that the traditional explanation of disparities that attribute the conditions to aberrations in the operations of market forces, while having some validity, may not provide a full explanation for Ghana and Zimbabwe’s predicament. It argues that whilst the existing disparities may be rooted in history, their persistence and worsening in the post-independence era could only be understood with reference to the corruption, nepotism and the mismanagement that have characterized these states since they gained their independence.