Browsing by Author "Amekudzi, L.K."

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    Comparative Study of the Impact of Climate Variability on Prevalence of Urinary Schistosomiasis: Cases at Sunyani Regional Hospital and among School Children in Atronie, Sunyani
    (Journal of Environmental Science and Engineering, 2011-11-20) Tay, S.C.K.; Amekudzi, L.K.; Tagoe, G.
    A study has been conducted to determine the impact of climate variability on Schistosoma haematobium infection among patients and school children in Sunyani between 2006 and 2009. Urine samples from the subjects were collected and examined in the laboratory using the Filteration technique for the detection and quantification of Schistosoma haematobium eggs. The prevalence rate of urinary schistosomiasis at the Sunyani Regional Hospital for 2006, 2007, 2008 and 2009 were found to be 0.24%, 0.55%, 0.55% and 0.75% respectively while that for Methodist Junior High School in 2008 and 2009 were 60.1% and 60.3% respectively. A decrease in the relative humidity and average annual rainfall were identified as factors contributory to the increase in urinary schistosomiasis prevalence rate. The temperature values obtained throughout the study period did not have any significant effect on the prevalence rate. The temperature values, however, were those that enhanced cercarial incubation (15-35 °C) with a resultant increase in shedding of cercariae leading to more infections among water contacts. The infection rate due to the stream Amama was 20.1%, while that due to river Tano was 36.6%. The highest risk group was children aged 15-19 years. Praziquantel was administered to treat the infection, producing a cure rate of 93%. Recognition of urinary schistosomiasis as a public health problem in Ghana is the main challenge to prevention and control of the disease.
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    Estimation of planetary boundary layer height from radiosonde profiles over West Africa during the AMMA field campaign: Intercomparison of different methods
    (Scientific African, 2019-11) Amekudzi, L.K.; Aryee, J.N.A.; Preko, K.; Atiah, W.A.; S.K., Danuor
    Deducing realistic planetary boundary layer heights (PBLH) is crucial for weather, climate and air quality models, despite its equivocal nature. In this paper, a comparative assessment of seven PBLH estimation methods has been performed, with radiosonde profiles taken during the African Monsoon Multidisciplinary Analyses (AMMA) project campaign from June, 2006 to July, 2007 over 18 locations in West Africa. First, PBLH was identified from the radiosonde profiles as the location of minimum gradients in mixing ratio (q), relative humidity (RH) and refractivity (N), and maximum gradient in potential temperature (θ). Other methods used to identify PBL tops were the statistical NS method and bulk Richardson (Rib) method at a critical threshold of 0.25. Next, a reference method (ho) was identified as the benchmark for PBL comparison. Visual inspection of the individual profiles allowed for assessing the ho method to yield reliable PBLH estimates. Thereafter, comparisons of the PBLH were performed for both convective and stable cases, with the stable boundary layer (SBL) height being generally below 700 m a.g.l for all methods, whereas, convective boundary layer (CBL) heights ranged between 300 m a.g.l and 1400 m a.g.l across different regions of the study area. Contrarily, the NS method failed to detect the SBL due to its inability to identify a dewpoint or virtual potential temperature discontinuity. Additionally, the Rib method, particularly in stable cases, yielded PBL tops consistent with the reference method (ho) whenever the NLLJ was clearly defined due to contribution of wind shear beneath the jet core to turbulent kinetic energy (TKE) production. Afterwards, the study domain was split into three zones and the performance of each method was assessed per each zone. Spatially, the CBL height was observed to grow thicker in the north-east direction over the dry, arid regions, where integral values of sensible heat rapidly converted by surface net radiation, has significant influence on the growth of CBL throughout daytime. Other likely reasons for this observation are advection, orography and mechanical turbulence production. However, a reversal was observed at night with the SBL being thinner in the dry, arid regions and rather relatively, higher in the coastal regions. Finally, the statistical assessment, coupled with visual inspection of the individual profiles, showed that the gradient methods (particularly N) outperformed the Rib and NS methods, yielding very low biases as well as, high and statistically significant correlation co-efficients. These results are useful for enhancing the performance of PBL models over the region. Possible limitations to the findings of this study are the different ascent times between the sites, as well as the number of ascents per site, which ∗ Corresponding author.
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    The impact of climate and land-use changes on the hydrological processes of Owabi catchment from SWAT analysis
    (Journal of Hydrology: Regional Studies, 2019-07-24) Amekudzi, L.K.; Osei, Marian Amoakowaah; Wemegah, David Dotse; Preko, Kwasi; Gyawu, Emmanuella Serwaa; Obiri-Danso, Kwasi
    Study region: The 69 km2 Owabi catchment in Ghana. Study focus: The Soil-Water-Assessment-Tool (SWAT) was used to assess the hydro-climatic variability resulting from anthropogenic activities from 1986 to 2015. Specifically, the model simulated historic and projected stream-flow and water balance. Future stream-flow projections were modelled for three climate ensembles under three different representative concentration pathways (RCPs) for two land-use categories. New hydrological insights for the region: Initial results revealed that forest and topography played major role in water loss, whereas evapotranspiration and surface runoff were the dominant modulating processes. Monthly calibration/validation of the model yielded acceptable results with NSE, R2, PBIAS and RSR values of 0.66/0.67, 0.67/0.67, 8.2%/8.0% and 0.59/0.58 respectively. Uncertainty was fairly low and the model enveloped about 50% of the observed stream-flow. The RCP projections for all land use categories showed decreasing rainfall and streamflow trends. The model proved efficient in determining the catchment hydrology parameters and has potential to be used for further modelling of water quality and pollution to aid in effective water management.
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    The impact of climate change on malaria in coastal Ghana
    (International Development Research Centre, 2014-12) Amekudzi, L.K.; Codjoe, S.N.A.; Sah, N.A.; Appiah, M.
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    Land Use/Cover Response to Rainfall Variability: A Comparing Analysis between NDVI and EVI in the Southwest of Burkina Faso
    (Climate, 2014-12) Amekudzi, L.K.; Zoungrana, Benewinde J.-B.; Conrad, Christopher; Thiel, Michael; Dapola Da, Evariste
    Abstract: A comparative analysis of the sensitivity of NDVI and EVI to rainfall indicators has been carried out for different land use/covers in the Southwest of Burkina Faso. Three classified land use/covers maps for 1999, 2006 and 2011 were produced and change detection was applied to locate persistent areas. Thereafter monthly vegetation indices of plots of 750 × 750 m2 were extracted from 2001 to 2011 for persistent woodland, mixed vegetation, and agricultural area within 5 km radius around four rain gauges. Furthermore, correlation analysis to measure the relationship between vegetation indices and rainfall indicators was performed. The results indicate some similarities between NDVI and EVI. Both indices, for all land use/covers, showed significant and strong positive correlation with the rainfall indicators. In general, NDVI was more sensitive to rainfall than EVI in the study area, but the difference between the Pearson’s coefficient values of both vegetation indices was insignificant. The findings of this work agree with some previous studies, but OPEN ACCESSClimate 2015, 3 64 contrasting conclusions were also noted in literature. Hence wider spatial investigation will be necessary to confirm the results of this paper
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    L’incidence des changements climatiques sur le paludisme dans les régions côtières du Ghana 1 © Moses Melphis Abai
    (International Development Research Centre Centre de recherches pour le développement international, 2015-04) Amekudzi, L.K.; Codjoe, S.N.A.; Sah, N.A.; Appiah, M.
    Dans les villes côtières du Ghana, les facteurs climatiques comme les inondations et le réchauffement ont une incidence sur la prévalence du paludisme. • Les conditions environnementales jouent un rôle essentiel dans la transmission de cette maladie, et les moustiques s’adaptent à des lieux non traditionnels pour se reproduire, comme les drains de surface obstrués. • Si l’on souhaite réduire l’incidence du paludisme, les communautés et institutions doivent participer pour éliminer les sites potentiels de reproduction des moustiques dans l’environnement. Il est également essentiel de mettre en œuvre des programmes d’éducation sanitaire et de lutte renforcée contre la maladie. • Entre 2020 et 2080, on estime que la saison de transmission maximale du paludisme (de mai à juillet) se décalera d’un ou deux mois en raison du décalage correspondant des périodes de pluie. • À long terme (2020-2080), la prévalence du paludisme devrait toutefois diminuer en raison d’une réduction des précipitations et de températures dépassant les 35 °C, des conditions peu propices à la reproduction des moustiques qui transmettent cet
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    MODIS NDVI trends and fractional land cover change for improved assessments of vegetation degradation in Burkina Faso, West Africa
    (Journal of Arid Environments, 2018-01-15) Amekudzi, L.K.; Dapola Da, Evariste; Thie, Michael; Conrad, Christopher; Zoungrana, Benewinde J-B.
    Reduction of natural vegetation cover in the savannah of West Africa constitutes a pressing environmental concern that may lead to soil degradation. With the aim to assess the degradation of natural vegetation in the savannah of Burkina Faso, this study combined NDVI trends and fractional Land Use/Cover Change (LULCC). Fractional LULCC maps, derived from the aggregation of a 30 m Landsat LULCC map (1999–2011) to 250 m resolution of MODIS, were used to assess natural vegetation conversions in the small-scale spatial patterns of savannah landscapes. Mann-Kendall's monotonic trend test was applied to 250 m MODIS NDVI time series (2000–2011) to assess modifications of natural vegetation cover. Finally, the Spearman's correlation was employed to determine the relationship of natural vegetation degradation with environmental factors. The study revealed a vast conversion of natural vegetation into agriculture (15.9%) and non-vegetated area (1.8%) between 1999 and 2011. Significant decreasing NDVI trends (p < .05) indicated negative modifications of natural vegetation (2000–2011 period) occurring along the protected areas borders and in fragmented landscapes characterized by disruption of continuity in natural vegetation. Spearman's correlation showed that accessibility, climatic and topographic conditions favored natural vegetation degradation. The results can enable the development of efficient land degradation policies.
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    Mosquito breeding site water temperature observations and simulations towards improved vector-borne disease models for Africa
    (Geospatial Health, 2015-02-18) Amekudzi, L.K.; Tompkins, Adrian M.; Asare, Ernest O.; Ermert, Volker; Redl, Robert
    Abstract An energy budget model is developed to predict the water temperature of typical mosquito larval developmental habitats. It assumes a homogeneous mixed water column driven by empirically derived fluxes. The model shows good agreement at both hourly and daily time scales with 10-min temporal resolution observed water temperatures, monitored between June and November 2013 within a peri-urban area of Kumasi, Ghana. There was a close match between larvae development times calculated using either the model-derived or observed water temperatures. The water temperature scheme represents a significant improvement over assuming the water temperature to be equal to air temperature. The energy budget model requires observed minimum and maximum temperatures, information that is generally available from weather stations. Our results show that hourly variations in water temperature are important for the simulation of aquatic-stage development times. By contrast, we found that larval development is insensitive to sub-hourly variations. Modelling suggests that in addition to water temperature, an accurate estimation of degree-day development time is very important to correctly predict the larvae development times. The results highlight the potential of the model to predict water temperature of temporary bodies of surface water. Our study represents an important contribution towards the improvement of weather-driven dynamical disease models, including those designed for malaria early forecasting systems.
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    Multi-Temporal Landsat Images and Ancillary Data for Land Use/Cover Change (LULCC) Detection in the Southwest of Burkina Faso, West Africa
    (remote sensing, 2015-09-18) Amekudzi, L.K.; Thiel, Michael; Zoungrana, Benewinde J-B.; Conrad, Christopher; Dapola Da, Evariste; Forkuor, Gerald; Löw, Fabian
    Abstract: Accurate quantification of land use/cover change (LULCC) is important for efficient environmental management, especially in regions that are extremely affected by climate variability and continuous population growth such as West Africa. In this context, accurate LULC classification and statistically sound change area estimates are essential for a better understanding of LULCC processes. This study aimed at comparing mono-temporal and multi-temporal LULC classifications as well as their combination with ancillary data and to determine LULCC across the heterogeneous landscape of southwest Burkina Faso using accurate classification results. Landsat data (1999, 2006 and 2011) and ancillary data served OPEN ACCESSRemote Sens. 2015, 7 12077 as input features for the random forest classifier algorithm. Five LULC classes were identified: woodland, mixed vegetation, bare surface, water and agricultural area. A reference database was established using different sources including high-resolution images, aerial photo and field data. LULCC and LULC classification accuracies, area and area uncertainty were computed based on the method of adjusted error matrices. The results revealed that multi-temporal classification significantly outperformed those solely based on mono-temporal data in the study area. However, combining mono-temporal imagery and ancillary data for LULC classification had the same accuracy level as multi-temporal classification which is an indication that this combination is an efficient alternative to multi-temporal classification in the study region, where cloud free images are rare. The LULCC map obtained had an overall accuracy of 92%. Natural vegetation loss was estimated to be 17.9% ± 2.5% between 1999 and 2011. The study area experienced an increase in agricultural area and bare surface at the expense of woodland and mixed vegetation, which attests to the ongoing deforestation. These results can serve as means of regional and global land cover products validation, as they provide a new validated data set with uncertainty estimates in heterogeneous ecosystems prone to classification errors.
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    Overview of surface to near‑surface atmospheric profles over selected domain during the QWeCI project
    (Meteorology and Atmospheric Physics, 2018-07-04) Aryee, J. N. A.; Amekudzi, L.K.; Atiah, W. A.; Osei, M. A.; Agyapong, E.
    Assessing the evolution of surface to near-surface atmospheric fuxes is key to improving our understanding of their interactions, while further advancing climate applications. In this paper, an overview of the diurnal to seasonal evolution of some surface to near-surface atmospheric fuxes, coupled with their interactions, have been provided. Fluxes of downwelling and upwelling radiation (SW↓, SW↑, LW↓, LW↑), soil heat fux (ΔH), relative humidity (RH), rainfall (RR) and surface air temperature (T), measured from two diferent locations (Owabi and KNUST) and at a temporal resolution of 10 min, encompassing the quantifying weather and climate impact (QWeCI) Project period (2011–2013), were used to assess their relationship on diurnal to seasonal scales. First, diurnal assessments of the various profles were performed. These provided information on the relatively active daytime, with the earth surface exposed to substantial SW↓, initiating rising and sinking thermals which subsequently increased T and ΔH, with reductions in RH until few hours after midday, beyond which a reversal was observed. Also, ΔH from the vegetative terrain (Owabi) was found to be directed into the surface at daytime, and released from the sub-surface layer back into the atmosphere at night time, compensating the energy loss by LW↑ from the surface. Furthermore, rainfall (RR) in both locations were found to be generally convective and occurring mostly between 1500 GMT and 2300 GMT. The relationship between net radiation (RN) and RR is presently statistically unclear, although rainfall peaks were found to be occurring at low RN and relatively warmer T, accompanied by high RH. Thereafter, seasonal assessments were performed to capture the monthly-averaged diurnal variabilities in the measured surface to near-surface parameters. These showed heightened daytime T, ΔH and RN, coupled with relatively low RH within the dry seasons, and more reduced profles within the monsoon season. Additionally, countrywide assessments were performed using ERA-5 datasets which showed similarities with the in situ data. However, convective rains over the domain were not fully resolved in ERA-5. Nonetheless, the fndings of this study are essential to understanding surface energy balance processes in tropical, humid climates, which is important for various climate-impact modeling applications and policy formulations over the region.
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    Overview of surface to near‑surface atmospheric profles over selected domain during the QWeCI project
    (Meteorology and Atmospheric Physics, 2018-07-04) Amekudzi, L.K.; Aryee, J.N.A.; Atiah, W. A.; Osei, M. A.; Agyapong, E.
    Abstract Assessing the evolution of surface to near-surface atmospheric fuxes is key to improving our understanding of their interactions, while further advancing climate applications. In this paper, an overview of the diurnal to seasonal evolution of some surface to near-surface atmospheric fuxes, coupled with their interactions, have been provided. Fluxes of downwelling and upwelling radiation (SW↓, SW↑, LW↓, LW↑), soil heat fux (ΔH), relative humidity (RH), rainfall (RR) and surface air temperature (T), measured from two diferent locations (Owabi and KNUST) and at a temporal resolution of 10 min, encompassing the quantifying weather and climate impact (QWeCI) Project period (2011–2013), were used to assess their relationship on diurnal to seasonal scales. First, diurnal assessments of the various profles were performed. These provided information on the relatively active daytime, with the earth surface exposed to substantial SW↓, initiating rising and sinking thermals which subsequently increased T and ΔH, with reductions in RH until few hours after midday, beyond which a reversal was observed. Also, ΔH from the vegetative terrain (Owabi) was found to be directed into the surface at daytime, and released from the sub-surface layer back into the atmosphere at night time, compensating the energy loss by LW↑ from the surface. Furthermore, rainfall (RR) in both locations were found to be generally convective and occurring mostly between 1500 GMT and 2300 GMT. The relationship between net radiation (RN) and RR is presently statistically unclear, although rainfall peaks were found to be occurring at low RN and relatively warmer T, accompanied by high RH. Thereafter, seasonal assessments were performed to capture the monthly-averaged diurnal variabilities in the measured surface to near-surface parameters. These showed heightened daytime T, ΔH and RN, coupled with relatively low RH within the dry seasons, and more reduced profles within the monsoon season. Additionally, countrywide assessments were performed using ERA-5 datasets which showed similarities with the in situ data. However, convective rains over the domain were not fully resolved in ERA-5. Nonetheless, the fndings of this study are essential to understanding surface energy balance processes in tropical, humid climates, which is important for various climate-impact modeling applications and policy formulations over the region.