Department of Earth Science
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Item Application Of The Rainfall Infiltration Breakthrough (Rib) Model For Groundwater Recharge Estimation In The Birim North District Of Eastern Region, Ghana(University Of Ghana, 2022-07) Antwi, N.D.Evaluation of Groundwater recharge from rainfall is essential for sustainable water resources management, particularly in arid and semi-arid environments. The Birim North District, where majority of the population relies on groundwater due to pollution of surface water sources, has already experienced a drop in groundwater levels attending to the cumulative impacts of human activities and climate change. This project applies the Rainfall Infiltration Breakthrough (RIB) methodology to estimate groundwater recharge in the shallow unconfined, saprolite aquifer system in the Birimian Province in Southwestern Ghana. The Water level fluctuation (WTF) approach was used to estimate groundwater recharge in order to check, augment, and confirm the Rainfall Infiltration Breakthrough (RIB) recharge estimates by comparing such groundwater recharge estimates. The specific yield values acquired from the previous studies were compared to those acquired using the linear regression model as a quality assurance measure. The validity of the analysis, i.e., the association between rainfall and groundwater level, was established as a result of this. The line drawn in the regression model for determining the specific yield corresponded to 0.06, which was close to the value (0.05) obtained from literature. The RIB model estimated local recharge at 2.9 % to 21.4% of mean annual precipitation (MAP). The WTF approach estimated recharge to be between 3.2 % to 22.6 %. The prediction showed that decreased rainfall had no effect on groundwater levels during the simulation period in the climate scenario analysis. However, the ratio of recharge rate to precipitation did not alter considerably; it was somewhat greater than the baseline. Correlation examination of rainfall and observed water level fluctuation (WTF) data at the monthly scale, along with recharge estimates derived from other approaches, indicated that the RIB results based on monthly data were plausible and could thus be utilized as recharge estimates. These findings suggested that using these methods to estimate groundwater recharge provides opportunities for assessing temporal variations in groundwater recharge and thus facilitates groundwater resources management. The method can estimate groundwater recharge in similar regions with adequately long time series of rainfall and groundwater levels. The RIB model is particularly suitable for shallow unconfined aquifers with minimal transmissivity; nonetheless, the RIB model's utility for application in various climatic locations and hydrogeological circumstances needs to be further investigated. These strategies could be tested in the future in catchments that have similar conditions of physiographic and hydrogeologic systems to the current research region.Item Hydrogeological And Hydrochemical Characterization Of Aquifers In The Akatsi Area, Ghana(University Of Ghana, 2022-05) Kassatchia, I.K.Groundwater remains the most significant source of water supply in the Akatsi area for multiple purposes. The demand for clean water supply is increasing year after year because of the growth of population and urbanisation in the district. However, without proper monitoring, the quality of groundwater is easily compromised by either natural processes or anthropogenic activities. Some of these activities comprise agriculture, improper disposal of domestic waste, and rock water interaction as found in the area. In addition, there is very little existing research work on the sustainability and quality of water resources in the study area. This study aimed to assess the hydrogeological and hydrochemical properties of aquifers underlying the Akatsi and surrounding areas. Then identify the major processes that influence groundwater hydro-chemistry and its suitability for diverse purposes in the study area. Hence, a thorough quality assessment of groundwater resources and characterization of aquifers of the Akatsi area was carried out by employing conventional graphical methods, and multivariate statistical methods, as well as the Cooper Jacob method using pumping test data. Conventional graphical techniques, R-mode Hierarchical Cluster Analysis (HCA), and Principal Component Analysis (PCA) revealed carbonate and silicate minerals weathering coupled with reverse ion exchange as well as the impact of domestic waste and agrochemicals as the key factors that control groundwater chemistry in the Akatsi area. Q-mode HCA combined with Stiff diagrams indicated that recharge zones are characterized by Ca-HCO3 low salinity waters, which evolve through rock-water interactions to Na-K-HCO3 high salinity waters in the discharge zones. Groundwater quality for domestic purposes was assessed using the weighted arithmetic index technique. The calculated values of water quality indices from the data suggest that over 91% of groundwater samples fall within "excellent" and "good" water categories, whereas 8.1% of the samples fall within the "poor" water category. Groundwater quality assessment for irrigation purposes based on the classification of United State Salinity Laboratory (USSL, 1964), Wilcox and Doneen's diagrams suggest groundwater from the study area is of suitable quality for irrigation purposes, but the levels of salinity increase towards the discharge zones, such that some of the boreholes in the discharge zones may not be acceptable for irrigation purposes on the soils of high salinities, which might affect the osmotic potentials of crops.Item Hydrological Modelling Of The Black Volta Basin In Ghana For Flood Forecasting(University Of Ghana, 2022-07) Yeboah, F.The occurrence and devastating impacts of floods have been on the increase in recent times at the global scale. This is probably one of the manifestations of climate change/variability. The Black Volta basin is one of the flood-prone areas in Ghana, and hosts one of the most vulnerable communities in the country. The frequency and severity of these disasters require concerted efforts towards mitigation. There is therefore the urgent need for a decision support system for effective management of floods and related disasters in the basin. The objective of this study is to develop a hydrological model based on existing data, duly calibrated with field observations, for the prediction of flood events and potential high flows in the Black Volta Basin. The outcome and output of this research will prove useful to basin managers, policymakers and disaster management organizations in the basin. In this study, the Hydrologic Engineering Center – Hydrologic Modeling System (HEC-HMS) version 4.5 hydrologic model is used for event based modelling of the Black Volta catchment within Ghana. Firstly, the Spatio-temporal trend of monthly and annual rainfall amount and intensity was analyzed for the basin for the period of 1980 to 2018 using the Mann-Kendal trend test and Sen’s slope estimator. On an annual scale, the basin recorded decreasing trend of rainfall amount, while the rainfall intensity showed an increasing trend. With this increasing trend of rainfall intensity, frequency of flooding in the area is expected to increase. In the event-based modeling, the Soil Conservation service (SCS) Curve Number loss approach was used to account for infiltration loss. Direct runoff and base flow were simulated using the SCS unit hydrograph method and the recession method, respectively, and the Muskingum-Cunge model used as channel routing. Calibration of the model was carried out using events in September 1996 and 2007, whiles August–September 1999 and September 2010 event were used for validation. The results yielded an overall NSE value of 0.919 for the calibration and 0.851 for the validation, indicating a good fit between the simulated and observed discharge. The calibrated model was then applied to forecast the runoffs for 2, 5, 10, 15, 20, 25, 50, 75 and 100 years return periods of rainfall using the 2016 IDF curves developed for the area. The simulated peak flows for 2 to 100 years return periods ranges from 1,568.8 m3/s to 2375.4 m3/s at Chache, 3251.7 m3/s to 5655.0 m3/s at Bui, and 8677.7 m3/s to 14941.4 m3/s at Bamboi station. Comparing these values to historical peak flow values within the basin, it is inferred that the range of predicted peak flows for the return periods have the potential of causing flood. This result forms the basis for characterization of floods in terms of return periods, and subsequent application in flood risk assessment within the basin.Item Palynology, Palynofacies And Organic Geochemical Analyses Of Cretaceous And Early Paleogene Sediments, Offshore Tano Basin, Western Ghana(University Of Ghana, 2021-09) Achaegakwo, C.A.Palynological analysis from two exploratory and one appraisal wells (Lynx-1X, Dzata-1 and Dzata-2A) and organic geochemical results from two wells (Dzata-1 and Dzata-2A) samples were obtained from the Middle Cretaceous-Early Tertiary of the Deepwater Cape Three Points offshore Tano Basin, Western Ghana. From the rich and well preserved palynomorphs recovered, the First Appearance Datum (FAD) and Last Appearance Datum (LAD) of stratigraphically significant species were used to propose four palynozones (PZ-I to PZ-IV) for the samples. Lynx-1X is Albian-Eocene, Dzata-1 and Dzata-2A wells are dated Albian- Maastrichtian, based on evidence of stratigraphically significant sporomorphs and dinocysts. The sporomorph associations recovered from the three wells exhibit similarity to Cretaceous Phytogeographic Provinces of African-South America (ASA). Sporomorphs recorded are characteristic of Albian-Cenomanian Elaterate Province for the deeper intervals and of the Senonian Palmae Province for the shallower intervals in all the wells. The Late Cretaceous peridineacean assemblage has a lot of similarity with those of Malloy or Tropical/Subtropical suite of Lentin and Williams (1980). Distribution of palynomorphs enabled the identification of two major sedimentary facies: the nearshore and open marine facies. The nearshore facies, concentrated at deeper intervals, are characterized by abundant sporomorphs and peridinoid dinocysts while the open marine facies are dominated by gonyaulacoid dinocysts and are restricted to the shallower intervals. This occurred as a result of marine transgression which flooded the area causing marine sedimentation. Palynofacies analysis carried out under transmitted microscopy defined seven palynofacies associations (PF-1 to PF-7) for Lynx-1X, five palynofacies associations (PT-1 to PT-5) for Dzata-1 and six palynofacies associations (PT-A to PT-F) for Dzata-2A wells. The first palynofacies assemblage in Lynx-1X well, PF-1, reflects deposition in a fluviodeltaic/ nearshore environment under a marginal dysoxic-anoxic basin condition with sediments typical of kerogen type III-IV (gas prone). PF-2 is deposited under a proximal suboxic-anoxic shelf conditions in a marginal marine/nearshore environment and sediments classified as kerogen type II/III (gas prone). PF-3 suggests deposition in a marginal marine to shallow marine environment under distal suboxic-anoxic conditions suggesting kerogen type II>I (highly oil prone). PF-4 is inferred to be deposited under a distal suboxic-anoxic basin condition in a shallow marine environment and sediments characterized by kerogen type II>I (highly oil prone). PF-5 indicates a deposition under a distal dysoxic-oxic shelf conditions in middle-outer neritic environment depicting kerogen type II>I (oil prone). PF-6 suggests a deposition in a shelf to basin transition condition in the inner-middle neritic environments indicating kerogen type III and II (oil prone). PF-7 reflects an outer neritic environment under distal mud-dominated oxic shelf conditions and characterized by kerogen type II/III (gas prone). In Dzata-1 well, PT-1 suggests deposition in a nearshore environment under proximal suboxicanoxic conditions with sediments typical of kerogen type II and III (oil prone). PT-2 indicates deposition in a dysoxic-suboxic conditions in a nearshore environment typifying kerogen type III (gas prone). PT-3 suggests deposition in a marginal dysoxic-anoxic basin condition in a fluvio-deltaic/nearshore environment typical of kerogen type III (gas prone). PF-4 represents inner-middle neritic to outer neritic environment deposited in distal dysoxic-oxic shelf conditions typifying kerogen type II>I (oil prone). PT-5 represents deposition in a nearshore iv environment under marginal dysoxic-anoxic basin conditions which is characterized by kerogen type III (gas prone). PT-A of Dzata-2A well indicates deposition in a nearshore to shallow marine (inner neritic) environment under a proximal suboxic-anoxic shelf condition with typical type II/III kerogen (oil prone). PT-B infers an inner neritic/nearshore depositional environment under dysoxicsuboxic conditions with facies characterized by kerogen type III or II (gas prone). PT-C is deposited under a distal dysoxic-oxic shelf conditions in environments ranging from nearshore/inner neritic to middle-outer neritic characteristic of kerogen type II>I (oil prone). PT-D indicates a nearshore/inner neritic depositional environment under marginal dysoxic anoxic basin conditions and facies constituted by kerogen type III (gas prone). PT-E suggests deposition in inner-outer neritic environment under distal suboxic-anoxic basin condition characteristic of kerogen type II≥I (highly oil prone). PT-F suggests a deposition in a nearshore/shallow marine environment under a distal dysoxic-anoxic shelf environment with facies characterized by kerogen type II/III (oil prone). Rock-Eval pyrolysis and TOC results for Lynx-1X and Dzata-2A wells indicates that most of the analyzed samples are thermally immature to marginally mature and have a good petroleum potential with the ?Turonian-Santonian age samples as a better potential source rocks than the Campanian-Eocene and Albian-Cenomanian source samples. Analyzed samples generally have low kerogen conversion.Item Ground Stiffness and Depth to Bed rock investigations Using Multichannel Analysis Of Surface Waves: A Case Study At A Reclaimed Landfill Site In Accra(University Of Ghana, 2021-12) Awuah, B.This study was undertaken in Accra over an abandoned landfill site on which the authorities of Apenkwa Presbyterian Basic School desire to build a school facility. Obtaining information about the ground condition of the study site to support the intended architectural design is crucial. The main objective of this study is therefore, to investigate the ground stiffness and depth to bedrock of the study site using the Multichannel analysis of surface waves (MASW) technique. Acquiring subsurface information using the MASW procedure is grouped into three phases: acquiring data from the field, extracting the fundamental mode dispersion curve, and inversion of dispersion curve. The inversion of the dispersion curve provides a 1-dimensional (1D) velocity profile that is a representative of the subsurface where a geophone on the surface picked a response of the source energy generated. Several 1D velocity profiles that make up a traverse line were stacked to produce a 2-dimensional (2-D) Vs profile. From the processed field data, it was observed that, the surveyed site has a shear wave velocity (Vs) ranging between 340m/s and 1925m/s. The Vs velocity showed five distinct clear cutting wide ranges. The shear wave velocity at a depth of 30m (Vs30) gave a least value of 350m/s and a maximum value of 1400m/s. From this information, it was concluded that, the study site has at least five different stratigraphic layers at a maximum depth of 30m. The bedrock of the site is estimated to a depth of 25 m representing deep-seated bedrock. The Vs30 information obtained suggests that the site falls under category B and category C of the National Earthquake Hazards Reduction Program (NEHRP) Soil Profile Type Classifications.Item Engineering Characteristics Of Compressed Earth Blocks Stabilized With Lime And Coconut Husk Ash(University Of Ghana, 2022-08) Yentumi, A.A.The cost of renting or owning a property in Ghana has risen considerably as a result of the country's growing population and increasing demand for housing. Expensive building materials is one of the causes of this situation. There is therefore the need to use locally available building materials to come up with innovative ways to provide sustainable housing for the citizens especially the low-income group. This research aims at investigating the engineering characteristics of compressed earth blocks stabilized with lime and coconut husk ash. Laterite blocks of size 300mm x125mm x 200mm were prepared using the following mix ratios: 0%, 5%, 10% lime, and 0%, 2%, 4% coconut husk ash (CHA). The block samples were tested for density, compressive strength, water absorption and abrasion resistance in order to observe their performance after 7, 14, 21 and 28 days of curing. Dry compressive strength increased by 38% - 110% as the amount of lime and CHA was increased in the blocks. Results show that blocks stabilized with 10% lime and 4% CHA recorded the highest compressive strength with a value of 2.53MPa which falls within the required building standards. The stabilized block samples recorded dry density values that were slightly higher than the un-stabilized block samples, as well as a higher resistance to water absorption than the un-stabilized block The durability of the blocks was determined by subjecting the blocks to abrasion resistance test. The stabilized blocks showed higher resistance as compared to the un-stabilized blocks with the blocks stabilized with 10% lime and 4% lime showed the highest resistance to abrasion of 3.0cm/g. The properties of the blocks were therefore improved by the introduction of lime and coconut husk ash. This study will be of great benefit to the construction industry since it provides a low-cost alternative to sandcrete blocks. These blocks are not only durable but also environmentally friendly. The use of coconut husk in compressed earth blocks also helps in solving regional waste disposal problem. This research will also be of benefit to low-income groups since it promotes affordable housing.Item Hydrochemistry And Stable Isotope Assessment Of Groundwater And Surface Water Bongo District, Upper East Region, Ghana(University of Ghana, 2018-07) Agana, A.EThe hydrogeochemical data of groundwater and surface water of Vea dam water of the Bongo District in the Upper East Region of Ghana were examined to determine the main factors controlling the groundwater chemistry and the resultant water type formed in order to determine the suitability of the water for different uses. Conventional graphical methods combined with multivariate statistical analysis are the main methods applied to groundwater and surface water hydrochemical and stable isotope ((δ2H and δ18O) data to identify the geochemical characteristics. Results from 25 groundwater and 20 surface water samples indicated that the concentrations of major ions were low. Based on total hardness and TDS, the groundwater ranged from moderately hard to hard and fell under fresh (TDS<1000 mg/l) water type. By comparing the chemical parameters of groundwater in the study with the WHO guidelines, groundwater was of excellent to good quality for domestic use except in certain locations where fluoride exceeded the permissible limit. Generally groundwater and surface water in the area were suitable for irrigation purposes based on the analysis of sodium absoption ratio, sodium percentage, sodium residue carbonate, permeability index, and magnesium harzard classifications. Conventional graphical plots of the hydrochemical data suggested that the dominant groundwater type was Ca-Mg-HCO3 water type which signified modern meteoric water recharge. Hierarchical cluster analysis (HCA) of the hydrochemical data, resulted in two clusters suggesting rock weathering and anthropogenic activities being the main processes controlling the water chemistry. On the basis of ratio the geochemical processes that control the hydrochemistry of groundwater types in the area were dissolution of carbonate, silicate mineral weathering and ion exchanges. The stable isotopic compositions suggested that there were no apparent hydraulic relationship between surface water and groundwater in the location. However, the result suggested that, both water system were recharged from local precipitation, indicating meteoric origin.Item Engineering Characteristics Of Compressed Earth Blocks Stabilized With Lime And Coconut Husk Ash(University Of Ghana, 2022-08) Yentumi, A.A.The cost of renting or owning a property in Ghana has risen considerably as a result of the country's growing population and increasing demand for housing. Expensive building materials is one of the causes of this situation. There is therefore the need to use locally available building materials to come up with innovative ways to provide sustainable housing for the citizens especially the low-income group. This research aims at investigating the engineering characteristics of compressed earth blocks stabilized with lime and coconut husk ash. Laterite blocks of size 300mm x125mm x 200mm were prepared using the following mix ratios: 0%, 5%, 10% lime, and 0%, 2%, 4% coconut husk ash (CHA). The block samples were tested for density, compressive strength, water absorption and abrasion resistance in order to observe their performance after 7, 14, 21 and 28 days of curing. Dry compressive strength increased by 38% - 110% as the amount of lime and CHA was increased in the blocks. Results show that blocks stabilized with 10% lime and 4% CHA recorded the highest compressive strength with a value of 2.53MPa which falls within the required building standards. The stabilized block samples recorded dry density values that were slightly higher than the un-stabilized block samples, as well as a higher resistance to water absorption than the un-stabilized block The durability of the blocks was determined by subjecting the blocks to abrasion resistance test. The stabilized blocks showed higher resistance as compared to the un-stabilized blocks with the blocks stabilized with 10% lime and 4% lime showed the highest resistance to abrasion of 3.0cm/g. The properties of the blocks were therefore improved by the introduction of lime and coconut husk ash. This study will be of great benefit to the construction industry since it provides a low-cost alternative to sandcrete blocks. These blocks are not only durable but also environmentally friendly. The use of coconut husk in compressed earth blocks also helps in solving regional waste disposal problem. This research will also be of benefit to low-income groups since it promotes affordable housing.Item Hydrochemistry And Stable Isotope Assessment Of Groundwater And Surface Water Bongo District, Upper East Region, Ghana(University Of Ghana, 2018-07-18) Agana, A.E.The hydrogeochemical data of groundwater and surface water of Vea dam water of the Bongo District in the Upper East Region of Ghana were examined to determine the main factors controlling the groundwater chemistry and the resultant water type formed in order to determine the suitability of the water for different uses. Conventional graphical methods combined with multivariate statistical analysis are the main methods applied to groundwater and surface water hydrochemical and stable isotope ((δ2H and δ18O) data to identify the geochemical characteristics. Results from 25 groundwater and 20 surface water samples indicated that the concentrations of major ions were low. Based on total hardness and TDS, the groundwater ranged from moderately hard to hard and fell under fresh (TDS<1000 mg/l) water type. By comparing the chemical parameters of groundwater in the study with the WHO guidelines, groundwater was of excellent to good quality for domestic use except in certain locations where fluoride exceeded the permissible limit. Generally groundwater and surface water in the area were suitable for irrigation purposes based on the analysis of sodium absoption ratio, sodium percentage, sodium residue carbonate, permeability index, and magnesium harzard classifications. Conventional graphical plots of the hydrochemical data suggested that the dominant groundwater type was Ca-Mg-HCO3 water type which signified modern meteoric water recharge. Hierarchical cluster analysis (HCA) of the hydrochemical data, resulted in two clusters suggesting rock weathering and anthropogenic activities being the main processes controlling the water chemistry. On the basis of ratio the geochemical processes that control the hydrochemistry of groundwater types in the area were dissolution of carbonate, silicate mineral weathering and ion exchanges. The stable isotopic compositions suggested that there were no apparent hydraulic relationship between surface water and groundwater in the location. However, the result suggested that, both water system were recharged from local precipitation, indicating meteoric origin.Item Evaluation of the Hydrogeological Relationship between Monitoring and Production Boreholes in the Upper West Region. Ghana(University of Ghana, 1996-11) Norgbe, B.Y.To evaluate the hydrogeological relationship between monitoring and production boreholes in the Upper West region of Ghana, a total of 192 boreholes were studied. Out of these, 23 are monitoring boreholes and 169 are production boreholes. The types of aquifers being tapped by these boreholes have also been identified to determine the adequacy of the existing network of the monitoring boreholes. The region is underlain by basement complex rocks. The rocks are composed of granites, granodiorites and granite-gneisses. Metamorphosed volcanic. schists and phyllites of the Birimian formation occur along the western pollution of the study area. Three aquifer types were identified from geologic logs and drillers logs in the Upper West region. These are the weathered rock aquifers, the fractured unweathered rock aquifers and the fractured Quartz vein aquifers. These aquifers are inter-related and where they occur in combination with thick overburden, yields are enhanced in such boreholes. Statistical analysis; such as correlation and regression analyses were used to determine the relationship between the borehole properties, while the Theis (1935) Recovery and Cooper-Jacob (1946) methods were used to calculate the aquifer characteristics. There is a significant relationship between overburden thickness and yields in the study area. About ninety percent of the boreholes studied have overburden thicknesses exceeding 15m with yields of not less than 10 I/min. General}". yields range between 4.5 IImin. and 270 I/min in the 192 boreholes~. The mean and standard deviation are 25.4 I/min and 20.3 I/min respectively. Close values of the mean and standard deviation of the borehole yields indicate the heterogeneous nature of aquifers in the area. An average decline of 4.1 m in static water levels was observed in the region. This was attributed to reduced recharge:. low rainfall, high rates of evapotranspiration, increased surface run-off and excessive withdrawal of water from the boreholes. Transmissivity values computed using the Cooper-Jacob(l946) method ranges from 1.2 ml/day to log.2 mI /day in 47 boreholes. The mean and standard deviation values are 35.2 ml/day and 30.1 ml/day respectively. The closeness of these values, again explains the wide variations and extremity in transmissivity values of basement rock aquirers In the Upper-West region. The Theis(193S) Recovery method was used to compute the transmissivity values of six boreholes. The values range from 19.5 to 213.4 ml/day, while those calculated using the Cooper-Jacob (l946) solution technique from the same boreholes range between 24.5 and 183.4 ml/day. It was noted that more accurate transmissivity values were obtained rrom the Theis (1935) Recovery method than obtained from the Couper-Jacob (1946) method. Step-drawdown results used to calculate the borehole efficiencies of five boreholes after one hour of pumping indicate that none of the boreholes analyzed have inefficiencies exceeding 75% in the study area. Finally, the studies indicate that there exists virtually little or no hydrogeological relationship between ninety, percent of the monitoring; boreholes and the production boreholes; hence the 23 monitoring: boreholes established across the region are not adequately monitoring the groundwater levels of the area. They are also not representative of the production boreholes in the study area.