Groundwater quality in the Wassa West District of the Western Region of Ghana

Reconnaissance hydrochemical survey of 56 wells was conducted in the Wassa West District with the objective of providing baseline data for the establishment of groundwater quality monitoring stations. The data acquired is used in this paper to assess the quality of groundwater in the District. Groundwaters are mainly mildly aggressive with pH values in the range 4.5–6.9. However, a few of the boreholes show strong acidic character (pH range 3.7–4.0). The conductivity values are in the range 37–780 mS cm-1 with a mean 246.4 mS cm-1 suggesting the groundwaters are generally fresh and have short residence time. The groundwaters are moderately hard to very hard with only 40% of thesamples representing soft waters. Groundwater quality is excellent with respect to major ions (Ca2+, Mg2+, Na+, HCO3 -,SO4 2-, Cl-) as they fall below their respective WHO guideline limits for water potability. Uncharacteristic of mining areas, trace metals loading of the groundwaters are generally low. All except aluminum, arsenic, barium, iron, manganese, mercury and nickel have concentrations well below the WHO guideline limits for water potability. Aluminum (0.0–2.5 mg l-1), iron (0.0–18.3 mg l-1) and manganese (0.0–2.41 mg l-1) are higher than WHO guideline limits of 0.2 mg l-1, 0.3 mg l-1 and 0.5 mg l-1 in more than 20%, 40% and 25% of the wells, respectively, and, therefore,pose significant aesthetic quality problems to groundwater quality. Mercury concentration exceeds the WHO guideline limit of 0.001 mg l-1 in all the wells during the rainy season and, thus, poses the greatest physiological threat for groundwater usage for drinking purposes in the District. Arsenic and barium exceeded the WHO guideline limit in less than 5% of the wells. Aesthetic problems can be eliminated using iron removal plants or aerators. These will induce the co-precipitation of trace metals with ferric oxyhydroxide. Limiting mercury usage in mining will curtail physiologicalproblems

Concentration of trace metals in boreholes in the Ankobra Basin, Ghan

Analysis of trace metals in groundwater from the Ankobra basin revealed high levels of iron, manganese and aluminium. Approximately 40% of boreholes had total iron concentration exceeding 1000 mg l-1 (maximum WHO permissible limit). Aluminium concentration varied from 0.1 mg l-1 to 2510 mg l-1 with a median value of 10.0 mg l-1.Approximately 20% of the boreholes had aluminium concentration exceeding the WHO maximum acceptable limit (200 mg l-1) for drinking water. Manganese concentration was in the range 6–2510 mg l-1 with a median of 356 mg l-1. Roughly 25% of the boreholes had manganese concentration higher than 500 mg l-1, which is the WHO maximum acceptable limit for drinking water. The concentration of mercury was higher than 1.0 mg l-1 (WHO maximum acceptable limit) in 60% of the boreholes during the rainy season but below detection limit in the dry season, suggesting anthropogenic origin for mercury in the groundwater. Other trace metals that occurred, but in insignificant concentration in boreholes, include lead, arsenic, nickel and selenium. Most of the boreholes with high trace metal concentrations were located in and around the Bawdie-Bogoso-Prestea area

Evaluation of groundwater resources potential in the Ejisu-Juaben district of Ghana

The increasing stress on freshwater resources due to ever-rising demands and profligate uses as well as growing population of Ejisu-Juaben District is an issue of great concern. The purpose of this study is to make a quantitative estimate of the available groundwater resources in the Ejisu-Juaben district for efficient utilization and management of groundwater resources. The methodology involved the collection and analysis of existing well data and chloride mass balance. The results indicate that the aquifers are composite and composed of weathered regolith of low permeability and high storage and overlying fissured bedrock of high permeability and low storage. Semi unconfined aquifers prevail in major portions, which constitute the principal source of groundwater. The depths of boreholes in the District range from 17 - 75 m with an average of 51 m. Generally Ejisu-Juaben district has low groundwater potential with mean yield, transmissivity and specific yield values of 2.8 m3/h, 12.5 m2/d and 0.95 m3/h/m respectively. Recharge in the district is estimated as 7 - 9% of the average annual rainfall of 1874 mm. The permanent water reserve of 326,064,375 m3 and recoverable water reserve of 130,425,750 m3 for the aquifer of the basement complex aquifer were estimated from the records of 97 boreholes

Potential impact of large scale abstraction on the quality of shallow groundwater for irrigation in the Keta Strip, Ghana

The potential impact of large-scale groundwater abstraction on the shallow groundwater and crop production within the Keta Strip was examined. The assessment was based on geophysical data, data on groundwater quality, soils, irrigation water requirement and hydrogeology of the Strip. The results indicate that the shallow groundwater can support only medium to high salt tolerant crops. This is consistent with the medium salt tolerant crops especially shallot and onion currently grown in the area. Large-scale irrigation of the Strip will require at least 2 x 107 m3 of water during the dry season. Abstraction of such large volume of water from the shallow aquifer will result in the lowering of water table by approximately 1.0 m per year. The consequence of this will be the up coning of the fresh/saline water interface probably by as much as 4.7 m, resulting in salinisation of the fresh water lenses particularly around the lagoon end where most of the shallot farms are situated. Apart from up conning, salinisation may result from ingress of brackish/saline water from the lagoon and sea into the fresh water lenses. Though post irrigation rainfall will be adequate to nullify the water table depression, once the fresh water is contaminated, it is extremely difficult to decontaminate. Consequently, the shallow groundwater will evolve from medium through high to very high salinity hazard to crops. Specific ions toxicity will also increase due to increment in the concentrations of individual ions. Thus, the previously freshwater will become unsuitable for the production of even high salt tolerance crops. This will effectively halt the lucrative shallot and other vegetable farming in the Keta Strip and thus signify socio-economic disaster for the Keta Strip in particular and Ghana in general

Reconnaissance Survey of Arsenic Concentration in Ground-water in South-eastern Ghana

Arsenic (As) analysis of 150 boreholes in the south-eastern part of Ghana (Accra, Eastern and Volta regions) revealed low to medium concentrations in the range of 2-39 mg l-1, with only 2% of boreholes tested having arsenic concentration exceeding 10 mg l-1 of the WHO (2004) maximum permissible level of arsenic in drinking water. The measurements were carried out in the field using the Wagtech Arsenator field test kit (Wag-We 100500) equipment, which gives direct readout of arsenic concentration in the critical range 2-100 mg l-1. Arsenic concentrations were in the range < 2–39 mg l-1 with mean (< 2 mg l-1) and median (< 2 mg l-1). Out of 150 samples analysed, 147 had As concentration below 10 mg l-1. Three boreholes in the Recent Sand Formation in southern Volta Region at Atitekpo, Mafi Devime and Woe Aklorbordzi had arsenic concentrations of 28 mg l-1, 19 mg l-1 and 39 mg l-1, respectively. Though the sample of boreholes tested was only approximately 10% of the total number of boreholes in the study, the distribution within the sample makes the generalization that the risk of arsenic contamination of rural water supply in southeastern Ghana is generally low plausible. In spite of this assertion, boreholes in the Recent Sandy Formation have to be critically assessed to determine the extent of arsenic contamination and, if possible, monitored.West African Journal of Applied Ecology Vol. 13 2008: pp. 16-2

Acidification of groundwater and its implication on rural watersupply in the Ankobra basin, Ghana

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Geochemical assessment of springs in the Ho District of Ghana using multivariate statistical technique

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Assessment of groundwater potential in the Sunyai and techiman areas of Ghana for urban water supply

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Chemical drinking water quality in Ghana : water costs and scope for advanced treatment

To reduce child mortality and improve health in Ghana boreholes and wells are being installed across the country by the private sector, NGO's and the Ghanaian government. Water quality is not generally monitored once a water source has been improved. Water supplies were sampled across Ghana from mostly boreholes, wells and rivers as well as some piped water from the different regions and analysed for the chemical quality. Chemical water quality was found to exceed the WHO guidelines in 38% of samples, while pH varied from 3.7 to 8.9. Excess levels of nitrate (NO3−) were found in 21% of the samples, manganese (Mn) and fluoride (F−) in 11% and 6.7%, respectively. Heavy metals such as lead (Pb), arsenic (As) and uranium (U) were localised to mining areas. Elements without health based guideline values such as aluminium (Al, 95%) and chloride (Cl, 5.7%) were found above the provisional guideline value. Economic information was gathered to identify water costs and ability to pay. Capital costs of wells and boreholes are about £1200 and £3800 respectively. The majority of installation costs are generally paid by the government or NGO's, while the maintenance is expected to be covered by the community. At least 58% of the communities had a water payment system in place, either an annual fee/one-off fee or “pay-as-you-fetch”. The annual fee was between £0.3–21, while the boreholes had a water collection fee of £0.07–0.7/m3, many wells were free. Interestingly, the most expensive water (£2.9–3.5/m3) was brought by truck. Many groundwater sources were not used due to poor chemical water quality. Considering the cost of unsuccessful borehole development, the potential for integrating suitable water treatment into the capital and maintenance costs of water sources is discussed. Additionally, many sources were not in use due to lack of water capacity, equipment malfunction or lack of economic resources to repair and maintain equipment. Those issues need to be addressed in combination with water quality, coordinated water supply provision and possible treatment to ensure sustainability of improved water resources