Lower Volta River Research Articles

Modeling and assessment of the techno-economic analysis of biogas and its potential for the generation of electricity from water hyacinth biomass

The study presents the economic feasibility assessment of converting the produced biogas from water hyacinth biomass into electricity. Approximately, 0.3793 m3CH4/kgVS was generated from the water hyacinth biomass. The research indicated that the available water hyacinth population on the Lower Volta River in the year 2020 could potentially generate a methane yield of 53.676 × 106m3. The volume of methane gas generated had the potential to produce an annual electricity output of 110.792 × 106 kWh, which could be integrated into the national grid. The economic analysis indicated positive results with an initial total investment cost of $67,273,700. The project showed a positive net present value (NPV) of $8,923,769 and a levelized cost of 0.172 $/kWh. The simple payback and equity payback periods were determined to be 5.5 and 11.3 years, respectively. Furthermore, a sensitivity analysis conducted showed that the project’s NPV remained positive when variations in input parameters such as initial cost, operations, and maintenance cost were less than 15% sensitive range. However, a 30% reduction in the feed-in tariff cost resulted in a negative NPV. In conclusion, biogas production from water hyacinth biomass in Ghana can make a significant contribution to the country’s energy mix and help alleviate the energy shortfall in rural areas.

The influence of particle size on biomethanation: a study of Eichornia crassipes biomass (water hyacinth) from the Lower Volta River in Ghana using fruit waste sludge as inoculum source

The influence of particle size on biomethanation: a study of Eichornia crassipes biomass (water hyacinth) from the Lower Volta River in Ghana using fruit waste sludge as inoculum source

The water quality, incubation period and fecundity of the prawn Macrobrachium vollenhovenii

The physicochemical and biophysical characteristics of the natural habitat of the African river prawn (Macrobrachium vollenhovenii) in the lower Volta River, Ghana, were surveyed as a prelude to assessing the optimal water quality requirement for hatching and larval rearing in captivity. Additionally, the fecundity of gravid females and incubation period were determined. The physicochemical and biophysical assessments were done at two sampling zones along the Volta River estuary. Gravid broodstock were collected from artisanal fishers, transported to a laboratory and maintained at 8 ppt until hatching. These females were used to estimate fecundity and determine incubation periods for M. vollenhovenii. A preliminary larval rearing trial was conducted at salinities of 0, 4, 8, 12, 16 and 20 ppt to determine the optimum range for growth and survival. The results from the study indicated that prawns were found from the littoral to the mid zones of the river where there were submerged aquatic plants. In terms of the water quality in the natural habitat of the prawn, the temperature, pH and dissolved oxygen levels were similar at the two zones (p > 0.05) but there were significant differences in salinity (p = 0.001), total dissolved solids (p = 0.001) and alkalinity (p = 0.003) levels at Ada Foah and Agave Afedome. The duration of egg incubation in M. vollenhovenii was 18 days, with eggs changing from orange at spawning to brown between the 9th and 14th day and grey between the 14th and 18th day before hatching. Fecundity ranged between 2,400 and 26,400 larvae per female. Although, hatching was successful, larval development could not proceed beyond the first larval stage owing to imbalances in the ionic ratios of minerals in the brackish water. Further studies are recommended to resolve the water quality challenges to ensure successful larval culture in captivity.

Linking Macroinvertebrates and Physicochemical Parameters for Water Quality Assessment in the Lower Basin of the Volta River in Ghana

The health of the lower basin of the Volta River in Ghana was evaluated in January–February and May–June 2016 using physicochemical parameters and benthic macroinvertebrates sampled at 10 locations. Selected environmental variables were compared to accepted environmental water quality standard values where applicable. Principal component analysis (PCA) and redundancy analysis (RDA) were used to analyse the association between the benthic macroinvertebrates distribution and physicochemical variables. Pesticide concentrations were generally below the limit of detection 0.01 and 0.005 µg/L for organophosphate/synthetic pyrethroid and organochlorines respectively. Nutrient levels were also generally low; however, significant differences existed between the values of physicochemical parameters at the different sampling sites and seasons (Monte Carlo permutation test; p = 0.002), as well as between the abundance of macroinvertebrates at the different sites and seasons (p = 0.002). The environmental variables dissolved oxygen (DO), phosphate, pH, substratum (p < 0.05), turbidity, conductivity, total dissolved solids, total solids and nitrate (0.05 < p < 0.10) significantly explained the variation in macroinvertebrate composition between sampling stations in the Volta River. Polypedilum fuscipenne, was positively correlated with turbidity and DO concentrations; Physa sp., Centroptilum sp., Centroptiloides sp., Phaon iridipennis and juvenile fish were positively correlated with nitrate concentration and pH and negatively correlated with turbidity and DO. Polluted sites were dominated by the snail Lymnaea glabra. This demonstrates that physicochemical parameters and macroinvertebrates could be applied to describe the water quality and improve the biomonitoring for water resources management and the environmental protection in the Lower Volta River.

Evaluating the spatial and temporal variations of aquatic weeds (Biomass) on Lower Volta River using multi-sensor Landsat Images and machine learning

Aquatic invasive weeds affect hydrological, ecological, and socio-economic activities on freshwater ecosystems. On the Lower Volta River (LVR) of Ghana, invasive aquatic weeds have been known to be nuisance to fishing, navigation, aquaculture, hydropower production and other agricultural practices in the area. While information on the spatial and temporal distribution of aquatic weeds would be beneficial in improving weed management and control measures on the river, such information is very scanty. Also, these aquatic weeds are also biomass resources, that can be transformed to bioenergy. Thus, this study evaluated the spatial and temporal variations of aquatic weeds on the Lower Volta River, and assessed their potential biomass for bioenergy production.Random Forest (RF) algorithm and Landsat images were used to map the distribution of the weeds in 1975, 2003, and 2020, respectively. Accuracy assessment results showed mean Overall Accuracy (OA) of 83.44% and mean User Accuracy (UA) of 79.24%. The results indicated that as of 1975, aquatic weeds covered only 1495 ha and appeared in some specific locations such as Kpong and Ada. However, by 2003, the weeds had spread to most parts of the river covering 5600 ha, which was an increase of approximately 4-fold within a period of 28 years. The area covered by the weeds, however declined by 1505 ha between 2003 and 2020. Thus, in 2020, water hyacinth covered about 36% of the aquatic weeds relative to 28% in 2003. The results showed that, the quantity of the water hyacinth biomass per unit area was 21.5 kg/m2. This result can also be used as the basis for resource assessment as well as determination of its viability for bioenergy production and strategies for its modern utilisation. The conversion of water hyacinth into bioenergy remains one of the best aquatic weed management strategies that must be adopted in LVR.

Population structure, fecundity and morphological characteristics of M. vollenhovenii (Herklots, 1857) on lower volta river basin channel, Ghana

Population structure, fecundity and morphological characteristics of M. vollenhovenii were studied around Lower Volta River, Ghana subject to dirt of information on this prawn species around the study location. The most prominent morphological characteristics already documented for identification of this species was rostrum bearing 13-15 continuous teeth dorsally and 4-5 teeth on its ventral part. These morphological traits formed the principal components for identification in this study. Results showed that morphological traits on second pereiopods such as presence of spines, spinules, teeth borne within the fingers, and dense projections of setae-like features on telson and uropod were observed relevant for identification purposes. Other results revealed that maximum total length recorded in this study (150-155mm) was higher than total length ranges (≤125mm) documented for this species in earlier studies. Consequently, two adult’s classes of prawns were identified (old adult class 81-120mm; and young adults 31-80mm) and older class was observed to be more in catches than the younger prawns. Absolute fecundity revealed that oocytes estimation varied with respect to seasons, ages of prawns and body sizes of specimens examined. In conclusion, this study observed that M. vollenhovenii fishery is operating in a sustainable manner at the time of this study around the study location.

Changes in the fish community of the Kpong Headpond, lower Volta River, Ghana after 25 years of impoundment

The Kpong Headpond was the second created on the Volta River after Akosombo Dam, primarily as a source of hydroelectric power generation and potable water supply, and additionally, it has supported some fish production in Ghana since impoundment. The changes in fish community of the Kpong Headpond were studied to provide baseline information for strategies formulation to support the socio-economic development of the reservoir. The study identified changes in the fish community of the reservoir by comparing occurrence, composition, relative abundance and relative importance estimates of fish species, families and trophic groups, from available previous studies in the reservoir. From the collated information all fishes identified in the reservoir were categorised based on occurrence and importance as disappeared, appeared, permanent, declined or important, to show current status. The results indicated that the fish community has experienced a shift in the composition and relative abundance of important species, families and trophic groups in terms of number and weight, while remaining ecologically balanced. Representatives of the families Osteoglossidae, Centropomidae and Characidae have declined while representatives of the families Claroteidae, Cyprinidae and Cichlidae have increased. The aufwuch-detritus and herbivores declined while semi-pelagic omnivores increased resulting in a shift in dominance to benthic and semi pelagic omnivores. The appearance of five species and the disappearance of 25 others indicated a dynamic restructuring of the fish community in the reservoir, as expected. Enforcement of fishing regulations including the use of appropriate gear and fishing methods, fishery access control, promotion of culture-based fisheries and improvement in fisher education are recommended topics for sustainable fisheries in the reservoir.

The susceptibility of Simulium damnosum s.l. larvae from the Volta River in southern Ghana to temephos after nearly eight years of intermittent treatment

Nearly 8 years of intermittent treatments with temephos on the lower Volta River at Senchi Rapids, Ghana, produced no change in the susceptibility of larvae of the S. damnosum complex to temephos [Abate (R)]. In contrast, 14 months of temephos treatment in southern Ivory Coast produced resistance. This difference can be explained by the relatively weak selection pressure exerted by the intermittent treatments on the Volta River and the frequent changes in the composition of the population as shown by cytotaxonomic identification of the larvae.

Preliminary schistosomiasis survey in the lower Volta River below Akosombo Dam, Ghana.

Snail surveys were carried out in Kpong Lake, in southern Ghana, and along the lower Volta River below the lake. Bulinus globosus and Biomphalaria pfeifferi were abundant in the Kpong Lake and B. truncatus and Biom . pfeifferi, especially the latter, were widespread below the lake. Urine surveys among primary school children at eight localities along the lower Volta showed Schistosoma haematobium prevalence rates of 38.8-96.2%. At Bator and Mepe , where records for an earlier survey were available for comparison, the present survey showed more than a doubling in prevalence rate in ten years: at Bator , from 27.1% in 1971-72 to 74.6% in 1981; at Mepe the corresponding figures were 36.4 and 88.0%. In Ghana infection with S. mansoni is less common than with S. haematobium and the known foci of S. mansoni transmission are few and widely scattered. In the present survey the disease is first reported along the lower Volta at Bator , Mepe , Adidome and Tefle , with prevalence rates ranging from 6.7% at Bator to 52.4% at Tefle . This survey has added an important focus of S. mansoni infection to those already known.