Volta Basin Research Articles

Application of Analytical Hierarchy Process (AHP) and Multi-Criteria Evaluation (MCE) for a case study and scenario assessment of flood risk in the White Volta Basin of the Upper East Region, Ghana

In recent years, Ghana, particularly the inhabitants of the Upper East Region, has experienced profound impact of flooding, largely attributable to the complex interplay of climatic factors. This research embarks on a comprehensive assessment of flood risk zones nestled within the White Volta Basin, situated in the Upper East Region. The study employs advanced cartographic methodologies and uses Geographic Information Systems (GIS) in conjunction with the Analytical Hierarchy Process (AHP) to systematically categorize areas susceptible to inundation. Leveraging geospatial datasets acquired from satellites such as Landsat and Sentinel. Topographic, slope, and Land Use/Land Cover (LULC) maps have been constructed. The empirical findings underscore the susceptibility of specific regions, including the Talensi District, territories within Bawku West, and some segments of the Bolgatanga Municipal area, to escalated flood risk. Additionally, the research underscores the high vulnerability of communities such as Nunku, Tolla, Zaare, Pwalugu, Balungu, Winkongo, Biung, and Tongo to the negative impact of inundation. Significantly, the study unveils a pivotal factor in the perpetuation of flood devastation—namely, the role of water discharge. This intrinsic linkage between discharge rates and flood occurrences underscores the pressing need to address this critical component in mitigation strategies to reduce adverse impacts on the basin’s resident communities. The insights derived from the study offer some level of hope for residents, providing essential knowledge concerning flood-prone areas and optimal timing for agricultural activities to safeguard their cherished livelihoods.

Application of DPSIR model to ascertain driving forces and their impacts on the Volta basin

Managing trans-boundary water and its watershed areas is a challenging task. The riparian countries sharing the boundary may have different economic and national goals that can dictate the pressures exerted on water bodies and their catchments areas. The pressure will have dire consequences on the environment, the climate and the sustainability of the Volta River. This paper seeks to apply the Driving Forces-Pressure-State-Impact-Response (DPSIR) framework as a model to ascertain the driving forces and their impacts on the Black and the White sub-basins of the Volta River. The research was carried out through desk study of literature, reports and policies on the Volta basin as well as information from international bodies such as World Bank, United Nations, and European Union among others. The DPSIR framework thus established the state of the ecosystem, pressure exerted, impact and the responses to provide scientific basis for decision-making and address the impacts on the Volta River. The DPSIR framework was focused on Ghana and Burkina Faso due to their large share of the basin. Burkina Faso's share of the Volta basin area is 43 %, whereas, that of Ghana is 41.6 %. The use of DPSIR model will help stakeholders and policy makers in proper decision making. It was therefore recommended that there should be policy regulations to reduce the impact on the environment.

Restoration measures of the riparian vegetation of the Black Volta Basin in Ghana: Experiences from the Lawra Municipality

The study is focused on measures put in place to restore the degraded riparian vegetation of the Black Volta Basin in the Lawra Municipality. The study is necessitated by the fact that much attention has not been given to rehabilitation of degraded riparian flora species in the Upper West Region by scholars and researchers. The current study aims at filling the knowledge gaps on restoration measures of degraded riparian flora species in the Lawra Municipality in particular and Upper West Region in general. Going by pragmatism as a research philosophy, the study employed the mixed methods research approach in data collection, analysis, and presentation. Computed values of the Shannon Wiener Index (0.686) and Simpson's Index (1.5328) show that the riparian vegetation of the Black Volta Basin in the Lawra Municipality has dwindled due to livelihood activities as compared to the Shannon Index (1.6406) and Simpson's Index (3.5511) of the riparian vegetation of the Burkina Faso site across the Black Volta Basin. The reduction in vegetative cover of the Black Volta Basin in the Lawra Municipality is confirmed by satellite images which demonstrate dwindling riparian vegetation in the years 2020 and 2021 as compared to the years 2000 and 2001. The current study also discloses that restoration of the riparian vegetation of the Black Volta Basin in the Lawra Municipality is a collaborative effort of local and external stakeholders using measures such as complete ban on farming activities within the riparian zone, creating a buffer zone, promoting natural regeneration and a total ban on logging in the riparian zone. The study concludes that restoration of the degraded riparian vegetation of the Black Volta Basin of the study area is a panacea for sustainable development. It is recommended that by-laws to prevent logging of riparian tree species should be enforced by local and external stakeholders of the riparian vegetation of the study area.

Analyses of crop water use and environmental performance of small private irrigation along the white Volta basin of Northern Ghana

Analyses of crop water use and environmental performance of small private irrigation along the white Volta basin of Northern Ghana

Diversity, Length-weight structure and Condition Factor of fish species and physicochemical changes in four reservoirs in Volta basin, Burkina Faso

Diversity, Length-weight structure and Condition Factor of fish species and physicochemical changes in four reservoirs in Volta basin, Burkina Faso

Evaluating Willingness to Sell Vegetation in the White Volta Basin in Northern Ghana

Concepts of ecosystem services have been developed to make explicit connections between human welfare and ecological sustainability for policy, development, and conservation initiatives. Economic concepts such as the distinction between prices and values, and the acknowledgment of their values are context-specific which may change across space and time. Contingent valuation is a survey-based economic technique for valuing non-market resources, such as vegetation. This method is often used to establish the amount people are willing to be compensated for maintaining the existence of an environmental feature such as a tree, shrub, or grass. The level of importance attached to provisioning services as well as cultural services and cultural heritage differ in the rural communities hence different cash values attached. It is often perceived that rural community members do not put monetary value on vegetation, the study is therefore aimed at establishing monetary value rural communities have value for vegetation. The study was conducted in two irrigated and two unirrigated landscapes consisting of about 54 communities and comprising 240 respondents. Participatory Rural Appraisal tools were used. Random Utility Theory was applied and used for the analysis. The willingness to sell vegetation was significant at a 5% confidence level concerning native, sex, age, education, and household head. Marital status was, however, not significant in all the landscapes. The price trend is observed to be across a landscape, from the catchment to the downstream ecosystem.

Developing a flood monitoring system by utilizing real-time satellite rainfall estimates and water energy budget-based rainfall-runoff inundation model in West Africa

Abstract. The African regions have been affected by frequent flood-related disasters. To support decision-makers in flood disaster management, a real-time flood monitoring system was established in the Niger and Volta basins under the Water disaster platform to enhance climate resilience in Africa (WADiRE-Africa). To bridge a gap between data unavailability and inaccessibility, the near-real-time satellite rainfall data (GSMaP-NRT) was evaluated and found to have a very low correlation (<0.4) with gauge data at daily scales and a higher correlation (>0.7) at monthly scales. The statistically bias-corrected GSMaP-NRT data was used in the Water and Energy Budget-based Rainfall-Runoff-Inundation (WEB-RRI) model to generate hydrological responses of the basins. As the simulated river discharges were overestimated, an additional correction method was employed for the GSMaP-NRT data to match well with observed discharges. The prototype system provides real-time flood information in both basins.

Application of machine learning techniques to predict groundwater quality in the Nabogo Basin, Northern Ghana

The main objective of this study was to map the quality of groundwater for domestic use in the Nabogo Basin, a sub-catchment of the White Volta Basin in Ghana, by applying machine learning techniques. The study was conducted by applying the Random Forest (RF) machine learning algorithm to predict groundwater quality, by utilizing factors that influence groundwater occurrence and quality such as Elevation, Topographical Wetness Index (TWI), Slope length (LS), Lithology, Soil type, Normalize Different Vegetation Index (NDVI), Rainfall, Aspect, Slope, Plan Curvature (PLC), Profile Curvature (PRC), Lineament density, Distance to faults, and Drainage density. The groundwater quality of the area was predicted by building a Random Forest model based on computed Arithmetic Water Quality Indices (WQI) (as dependent variable) of existing boreholes, to serve as an indicator of the groundwater quality. The predicted WQI of groundwater in the study area shows that it ranges from 9.51 to 69.99%. This implied that 21.97 %, 74.40 %, and 3.63 % of the study area had respectively the likelihood of excellent. The models were found to perform much better with an RMSE of 23.03 and an R2 value of 0.82. The study conducted highlighted an essential understanding of the groundwater quality in the study area, paving the way for further studies and policy development for groundwater management.

Evaluating climate change scenarios in the white volta basin: A statistical bias-correction approach

This study provides a critical assessment of future climate scenarios in the White Volta Basin (WVB), an area heavily reliant on groundwater resources. With monthly model results for two Shared Socioeconomic Pathway Scenarios (SSP2-4.5 and 5–8.5), seven (7) Coupled Model Intercomparison Project Phase 6 (CMIP6) models with spatial resolution ranging from 1.125° × 2.8° were assessed. The study also considered, three 30-year time intervals, 1971–2013 for the Baseline (historical) climate, the 2020s (2020–2040) 2050s (2041–2070), and the 2080s (2071–2075) for the future climate scenarios. The Climate Change for Watershed Modeling (CMhyd) software was used for bias correction of these models, with observational data sourced from the National Centers for Environmental Prediction's Climate Forecast System Reanalysis (NCEP CFSR) and 12 gridded climate stations. The bias-corrected models validated using R2, NSE, RMSE, PBIAS, and additional metrics, demonstrated good calibration results compared to observed data. Precipitation ensembles showed 97–99% R2, 94–99% NSE, 70–485 mm RMSE, and -9-5% PBIAS. Maximum and minimum bias corrected temperatures performance varied from 95 to 99% R2, 92–99% NSE, 0.01–0.07 RMSE, and 0.01–0.23 PBIAS, Overall, precipitation levels are expected to decline for SSP2-4.5, while under SSP5-8.5 are expected to increase until the 2080s across all scenarios in comparison to the baseline period. Maximum temperature will be considerably high under SSP5-8.5, with an estimated increase of around 4.3 °C/year in comparison to the reference period. The monthly average variation in the maximum temperature ranges from 0.62 to 2.43 0Cunder the SSP5-8.5 scenario. These findings reveal the potential impacts of climate change on agricultural productivity, groundwater recharge, and crucial information for the development of Ghana's National Determined Contributions (NDCs) and National Adaptation Plans (NAPs). Thus, emphasizing the need for comprehensive adaptation strategies to mitigate the climate change impact on water resources and ecosystem services.

Flood risk assessment and adaptation under changing climate for the agricultural system in the Ghanaian White Volta Basin

In the context of river basins, the threat of climate change has been extensively studied. However, many of these studies centred on hazard analysis while neglecting the need for comprehensive risk assessments that account for exposure and vulnerability. Hazard analysis alone is not adequate for making adaptive decisions. Thus, to effectively manage flood risk, it is essential to understand the elements that contribute to vulnerability and exposure in addition to hazard analysis. This study aims to assess flood risk (in space and time until the year 2100) for the agricultural system, in the White Volta Basin in northern Ghana. Employing the impact chain methodology, a mix of quantitative and qualitative data and techniques were used to assess hazard, exposure, and vulnerability. Multi-model climate change data (RCP 8.5) from CORDEX and observation data from the Ghana Meteorological Agency were used for hazard analysis. Data on exposure, vulnerability, and adaptation were collected through structured interviews. Results indicate that flood hazard will increase by 79.1% with high spatial variability of wet periods but the flood risk of the catchment will increase by 19.3% by the end of the twenty-first century. The highest flood risk is found in the Upper East region, followed by North East, Northern, Savannah, and Upper West for all four analysed periods. Adaptive capacity, sensitivity, and exposure factors are driven by poverty, ineffective institutional governance, and a lack of livelihood alternatives. We conclude that the region is highly susceptible and vulnerable to floods, and that shifting from isolated hazard analysis to a comprehensive assessment that considers exposure and vulnerability reveals the underlying root causes of the risk. Also, the impact chain is useful in generating insight into flood risk for policymakers and researchers. We recommend the need to enhance local capacity and foster social transformation in the region.

Evaluating groundwater resources trends through multiple conceptual models and GRACE satellite data.

In this research, three numerical groundwater flow models, developed and calibrated from three equally plausible conceptual models over the Nasia Basin, have been used to assess groundwater resources variations over a transient period. The use of multiple numerical models reduces the effect of uncertainties in conceptual model formulation. All the three calibrated numerical models indicate an increasing trend of groundwater recharge and storage over the period of the groundwater level monitoring. This suggests that the prevailing erratic climatic conditions in the area are conducive for increasing groundwater recharge and storage in the terrain. The high-intensity, short duration rainfall patterns, attending climate change in the basin, enhance high levels of infiltration and percolation, leading to steadily increasing groundwater recharge. Groundwater recharge estimates from each of the models over the transient period appear to reflect the pattern of seasonal variations in rainfall in the region. Data from the models indicates a significant role of baseflow in sustaining perennial streamflow in the area. This presents a significant development in terms of groundwater-based adaptation projects, especially in agriculture. The trend of groundwater recharge in the Nasia Basin is in sync with regional groundwater storage variations estimated from the Gravity Recovery and Climate Experiment (GRACE) satellite data collected and processed over the Volta Basin. At the Volta Basin level, groundwater storage variations indicate a strong positive trend of increasing groundwater recharge from 2002 (beginning of the GRACE mission) to 2022 (end point of the data used for this research). Analysis of the GRACE data suggests that there is a cumulative increase in groundwater storage by 30cm, representing approximately 120 km3 of groundwater over the period in the basin. This translates into approximately 15mm/year of groundwater storage increase. Thus, at both the regional and local levels, groundwater appears to be responding positively to the impacts of erratic rainfall patterns observed in the area recently. The high-intensity, short duration rainfall patterns appear to favor significant groundwater recharge, resulting in a strong positive groundwater storage signal. The high positive groundwater storage signal suggests increasing groundwater resources potential in the area, indicating promising opportunities for groundwater-based climate change adaptation interventions.

Neoproterozoic passive margin formation and evolution during the Rodinia–Gondwana supercontinent cycle at the eastern margin of the West African Craton

Abstract Petrographical and geochemical data from the Togo structural unit (TSU), also referred to as the Atacora structural unit, are presented together with the existing dataset; geochemical and age data from the sedimentary and metasedimentary rocks from the passive margin sequences of the Dahomeyide belt in Ghana to infer their provenance and depositional setting and expand the discussion on the Rodina–Gondwana supercontinent assembly during the Pan-African orogeny. The metasedimentary rocks of the TSU are quartzites and phyllites. The framework grains of the quartzites consisting dominantly of quartz and small amounts of feldspar grains and relict lithic fragments classify them as quartz arenite, subarkose and sublitharenite. Generally, the studied rocks show similar rare-earth element and multi-element patterns, which imply derivation from similar sources. Elemental ratios, including (La/Lu)N, Th/Sc and La/Sc, suggest sediments sourced from intermediate to felsic rocks. Provenance and depositional setting indicators of the TSU suggest deposition in a passive margin setting, with the West African and Amazonian cratons’ granitoids and granitic gneisses as possible provenance, akin to siliciclastic rocks of the Buem structural unit and the Voltaian Supergroup of the Volta Basin. The deformational history of the TSU is similar to those of the Buem structural unit and the eastern margin of the Voltaian Supergroup, indicating the effect of the Pan-African orogeny on the passive margin of the Dahomeyide belt. We, therefore, propose the formation and evolution of a Neoproterozoic passive margin unit, which was tectonically deformed during the Rodinia–Gondwana supercontinent cycle.

Contribution of Aeromagnetic Data to the Structural Discontinuities Identification of Black Volta Catchment Aquifer System in Côte d'Ivoire

This paper focuses on improving the structural knowledge of the fissured aquifers of the Black Volta catchment in Côte d'Ivoire based on the mapping of magnetic lineaments, which represent magnetic discontinuities such as magmatic body contacts or tectonic faults. Four filtering methods, pole reduction (equator), gradient (vertical and hori-zontal), upward extension, and angle tilt, were applied to the residual magnetic field map to extract magnetic discontinuities while using the Oasis Montaj (Geosoft) program. Euler deconvolution coupled with the analytical signal provided, in addition to the horizontal location of the magnetic contacts, is an indication of their depths. The resulting structural map contains 458 structures, with lengths ranging from 9.03 to 66.54 km. Three directions, NW-SE, E-W and NE-SW, were detected with a predominance of the NW-SE direction. Depths estimated by Euler solutions range from 6.8 to 2847 m. This map is consistent with many faults already recognised or assumed by traditional structural studies and tectonic events affecting the Ivorian basement. These results contribute significantly to the improvement of the structural map of the Black Volta Basin in Côte d'Ivoire. In addition to the major known tectonic faults, numerous lineaments, particularly those at depth, have been highlighted by the present study.

Analysis of the Hydrodynamic Properties of the Fissure Aquifers of the Black Volta Catchment in Ivory Coast

The present study aims to analyze the productivity of aquifers in the Ivorian part of the Black Volta basin. It proposed to characterize the intrinsic hydrodynamic parameters of the productivity and to know the influence of these on the productivity of the drillings. The hydraulic parameters of the catchment structures and the pumping test sheets were used to determine the hydrodynamic properties through a methodological approach integrating Cooper Jacob's empirical formulas and automated calculations using the Pumping Interpretation Assistance Tool (OUAIP). A standardized principal component analysis (ACPN) was used to analyze the correlation of the different parameters. The results obtained range over several orders of magnitude. The values of the specific flow oscillate between 0. 01 and 4.87m²/h while the transmissivity varies between 1.25E-07 and 7.34E-03 m².s-1. As for the critical flow, it is between 0.869 and 26.6 m3/h. These values indicate that the aquifers generally have low specific flow rates, but fairly good transmissivity. The Normalized Principal Component Analysis (ACPN) allowed to highlight the different productivity factors of the aquifers in the region: water level variation, and hydraulic role of fractures. It also showed the influence of the depth of the drilling on productivity. These results contribute to the knowledge of the structure and hydrodynamic functioning of the aquifers of the basin basement. They show the structural links between hydrodynamics and aquifer productivity.

Water yield of the Volta Basin under future land use and climate change

Water yield of the Volta Basin under future land use and climate change

Evaluation of porosity and permeability of sandstones within the Oti Group of the Volta Basin using petrophysical and petrographic techniques

Evaluation of porosity and permeability of sandstones within the Oti Group of the Volta Basin using petrophysical and petrographic techniques

Trend of traffic on inland waterways of Port Harcourt urban coastal environment: a comparative safety imperative for a Ghanaian coastal regional province

The purpose of the study is to compare mobility and access in Sub- Saharan Africa urban cities of Nigeria and Ghana by analysing trends and accident probabilities on the inland waterways to improve safety standards. Primary data from100 respondents through structured data and interview from boat and ferry operators were used. The responses were ranked on a four-point scale based on the selected routes’ average accident probabilities in percent: Very Safe {0-20}, Fairy Safe {21- 50}, Unsafe {51- 80}, and Very Unsafe {81- 100}. Secondary data from the National Inland Waterways Authority (NIWA) and Ghana Maritime Authority (GMA) and the Volta Lake Transport Company (VLTC) were subjected to probability, percentage and trend analysis. Results indicate that in the Niger delta for every journey there is approximately 59% likelihood of fatal accident; while on the Volta Lake there is a likelihood of 7% fatal accident occurrence. The trend of traffic was high in the Niger delta noticeably in the routes of Akwa- Ibom. Cross Rivers and Rivers State. The Volta Lake recorded high traffic volumes on the routes of Yeji,Tapa Abo and Bidi on market days while on non-market days, Makango. Kwamekrom and Kpechu had high passenger volumes. Estimated annual passenger traffic on the Niger delta routes outweighed that on the Volta Lake routes on a ratio of 4:1. Safety analysis further reveals that the water ways of Port Harcourt in Rivers state were unsafe for travel while the water ways of the Volta Lake were relatively safe as revealed by the average probability ratio of 8:1 in comparative terms. The log linear regression analysis reveals a price elasticity of demand for boat transport of 1.00 and 0.97 for the selected route of Port Harcourt Nigeria and Volta Lake, Ghana respectively. It further supports the fact that more passengers were responsive to travel by waterways in Nigeria than Ghana. The study concludes that waterways of Niger delta basin have high risk indices and likelihood of accident occurrence than the Volta basin; and recommends that VLTC and NIWA should invest optimally and partner with the private sector to enforce and regulate the waterways operations so as to increase safety and mobility of users of the waterways.

An inventory of birds and extent of damage to rice farms at the Kpong Irrigation Dam in the Lower Volta Basin, Ghana

This study aimed to assess the incidence of birds raiding rice fields in the Kpong Irrigation Dam area of Ghana. Structured questionnaires were used to interview rice farmers in order to identify the bird species involved, quantify the economic losses incurred, and determine the mitigation measures employed by farmers. The main bird species identified as actively raiding rice fields were Ploceus cucullatus, Ploceus nigerrimus, Spermestes cucullatus, Spermestes bicolor, Quelea erythrops, and Dendrocygna viduata. The economic loss associated with bird raiding was estimated to range from 1,000.00 GHC (124.61 USD) to 1,500.00 GHC (186.92 USD), considering an exchange rate of 8.06 GHC to 1.00 USD at the time of the study. Additionally, farmers incurred 20.00 GHC in daily overhead labour costs to prevent bird raiding. Bird raiding on rice fields not only caused substantial economic losses but also had unintended social consequences. These included increased students’ absence from school and farmers' inability to attend and participate in family, community, and other social gatherings. The study highlights the need for practical and efficient methods to mitigate the effects of bird raiding. Given the significant economic and social impacts, it is crucial to develop strategies that effectively reduce bird raiding in rice fields.

Projections of precipitation extremes over the Volta Basin: insight from CanESM2 regional climate model under RCP 4.5 and 8.5 forcing scenarios

Projections of precipitation extremes over the Volta Basin: insight from CanESM2 regional climate model under RCP 4.5 and 8.5 forcing scenarios

Analyses of crop water use and environmental performance of small private irrigation along the white Volta basin of Northern Ghana

Small private irrigation (SPI) is a farmer-initiated irrigation which has the potential to increase the contribution of the overall irrigation sector to global food security. However, there is no much information about these systems for effective policies for regulation. This study compared the resource use productivities and environmental impacts of SPI systems to those of a government-led irrigation scheme (GIS) in Northern Ghana. The results showed that land productivity was higher in the SPI than in the GIS. Productivity per unit cultivated area was 2571.00 US$/ha under SPI while that of the GIS was 676.00 US$/ha. Output per unit command area was also two times higher in the SPI than in the GIS; that is 2571.00 US$/ha and 1113.00 US$/ha for SPI and GIS respectively. For water productivity, output per unit irrigation supply was 0.33 US$/m3 and 0.08US$/m3 for SPI and GIS respectively while output per unit water consumed by ET was 0.60 US$/m3 for SPI and 0.06 US$/m3 for the GIS. The results implied that the SPI schemes performed better in land and water productivities compared with the GIS which is attributed to higher yields and the selection of high valued crops by farmers under SPI. However, both irrigation system types at the time of this study did not cause significant deterioration to the water bodies and surrounding environment as the biochemical oxygen demand (BOD) values of nearby water bodies were less than 3.0–5.0 mg/l, which is considered as acceptable levels for drinking water by World Health Organisation (WHO) while salinity levels were also within acceptable limits (<750 μS/cm). With appropriate policies to regulate and provide support systems to the SPI, these systems may increase the overall agricultural productivity and improve job creation for the teeming unemployed youth and women in the savannah agroecological zone of Ghana.