Vegetation plays a key role in the global climate system via modification of the water and energy... more Vegetation plays a key role in the global climate system via modification of the water and energy balance. Its coupling to climate is therefore important particularly in the tropics, where severe climate change impacts are expected. 10 Vegetation growth is mutually controlled by temperature and water availability while it modifies regional climate through latent heat flux and changes in albedo. Consequently, understanding how projected climate change will impact vegetation and the forcing of vegetation on climate for various land cover types in East Africa is vital. This study provides an assessment of the vegetation trends in East Africa using Leaf Area Index (LAI) time series for the period 1982 to 2011, lead/lag correlation analysis between LAI and climate, a statistical estimation of vegetation feedback on climate using lagged 15 covariance ratios as well as spatial regression analysis. Our results show few significant changes in current LAI trends though persistent declining vegetation trends are shown from Southern Ethiopia extending through Central Kenya into Central Tanzania. Precipitation (temperature) exerts widespread positive (negative) forcing on lagging vegetation except in forests. Positive correlations between the lagging Antecedent Precipitation Index (API) and LAI were dominant compared to temperature. Positive vegetation feedback on precipitation dominates across the region while a stronger negative forcing is 20 exerted on Tmin compared to Tmax. Spatial dependence was also shown as a key component in the vegetation-climate interactions in the region. Given the vital role of land surface dynamics on local and regional climate, these results provide a valuable point of reference for evaluating the land-atmosphere coupling in the region.
The parameter uncertainty in hydrological modelling has been accorded much attention in the recen... more The parameter uncertainty in hydrological modelling has been accorded much attention in the recent past. Parameter uncertainty is a major source of overall model unreliability. In this study, the HydroPSO R package was used to assess parameter identification and uncertainty for the Soil and Water Assessment Tool (SWAT) model applied in the upper reaches of Nzoia River Basin. Fourteen parameters were selected based on previous studies and parameter sensitivity analysis using the Latin Hypercube Sampling method.
A pandemia causada pelo coronavírus (COVID-19/SARS-Cov-2) tornou-se um problema mundial, afetando... more A pandemia causada pelo coronavírus (COVID-19/SARS-Cov-2) tornou-se um problema mundial, afetando inúmeros setores essenciais, incluindo o educacional, impossibilitando aos alunos irem à escola para estudar e fazendo com que mantivessem um distanciamento social em casa. Como uma das formas de conter o avanço da pandemia, as escolas foram fechadas entre março e abril de 2020. A secretaria de Educação do Estado de Goiás, com o intuito de garantir a continuação do ensino, propôs a implantação do Regime de Aulas Não Presenciais (REANP), no qual a escolaridade foi transferida para a casa dos alunos, e as interações entre docentes e discentes estabeleceram-se por meio da utilização de mídias de ensino à distância. Tendo em vista o desafio da migração do sistema educacional presencial para o online, este estudo objetivou explorar as percepções dos alunos do Centro de Educação em Período Integral Dom Veloso-CEPI Dom Veloso, situado na cidade de Itumbiara-GO, frente a aprendizagem remota em tempos de pandemia. A pesquisa foi de caráter quali-quantitativo, e a coleta de dados realizada por meio de aplicação de questionário anônimo, estruturado e autoaplicável, este subdividido em categorias, sendo elas: características gerais, percepção do aluno quanto ao REANP, tecnologias inclusivas e questões direcionadas ao ensino médio quanto à escolha de profissão. O questionário foi respondido entre os dias 09 a 16 de setembro de 2020 por 7 turmas do Ensino Fundamental II e 6 de Ensino Médio, totalizando 118 participantes. A análise dos dados foi realizada por estatística descritiva e processados em planilha eletrônica, de onde foram retiradas as categorias e subcategorias mais significativas por percentuais. As respostas subjetivas foram consideradas em sua totalidade como indicadores para a realização de futuras propostas pedagógicas. Esta pesquisa contribui com a literatura de colaboração online entre escola, comunidade, professores, responsáveis e alunos, pois possibilita analisar como tem sido o processo de transição do ensino presencial para o meio virtual e as ações que mais impactam no sucesso da aprendizagem dos alunos, evidenciando ainda, uma forte tendência das novas tecnologias serem utilizadas como ferramentas perenes no processo de ensino-aprendizagem.
.................................................................................................... more .................................................................................................................. xvi CHAPTER ONE ..............................................................................................................
Scientific literature on the assessment and projection of climate change impacts suggests that th... more Scientific literature on the assessment and projection of climate change impacts suggests that the rapidly changing climate conditions are causing far-reaching consequences on natural resources and agricultural production. Atmospheric general circulation models (GCMs) have been widely used to simulate the present climate and to predict future climatic change at the global-scale. However, the assessment and projection of climate change at regional and national scales requires high resolution and consistent climate data to ensure that the scale and accuracy of results will enable planning for adaptation. This data can be obtained by downscaling the simulated output from GCMs using the appropriate predictors. However, this process is characterized by uncertainty due projections generated with multiple GCMs. This paper provides a summary of research developments in the use of GCMs for the assessment and projection of climate change impacts. The different techniques which have been used ...
<p&amp... more <p>Effective modeling of surface water and energy balance is crucial in planning and management of regional resources. However, the heterogeneous and clumped vegetation structure controls the portioning of land surface water and energy fluxes, which leads to large variations of local radiative and hydrological processes. The aim of this study is to characterize the land surface heterogeneity in East Africa and examine the impact of the spatially and temporally varying vegetation parameters on energy and water balance in the region.  We used MODIS datasets on Leaf Area Index (LAI), Enhanced Vegetation Index (EVI) and albedo to derive time-varying vegetation parameters for the period 2001 – 2011 period at 0.05° resolution. These parameters were integrated with the Variable Infiltration Capacity (VIC) model to characterize the effects of varying vegetation properties on surface water and energy fluxes. A twin simulation was also carried based on seasonally averaged vegetation parameters to isolate the effects of time-varying and spatially heterogeneous parameters on the water and energy fluxes. The simulation results were compared to rigorously validated global datasets on evapotranspiration and sensible heat. Results showed that the time-varying and spatially heterogeneous vegetation parameters provided surface water and energy fluxes which were more consistent with the validation datasets. The simulated evapotranspiration matched reasonably well with the observed values particularly in areas characterized by sparse vegetation and which are more prone to human influence. The improvements were highly noticeable in grassland and savanna land cover types. However, due to intensive human activities in region which affect not only the lad cover but also the vegetation structure, there is need for characterization of the land cover parameters based on high resolution data which can better capture the land surface heterogeneity in the region.</p>
Vegetation plays a key role in the global climate system via modification of the water and energy... more Vegetation plays a key role in the global climate system via modification of the water and energy balance. Its coupling to climate is therefore important, particularly in the tropics where severe climate change impacts are expected. Consequently, understanding vegetation dynamics and response to present and projected climatic conditions for various land cover types in East Africa is vital. This study provides an assessment of the vegetation trends in East Africa using Leaf Area Index (LAI) time series for the period 1982 to 2011, regression analysis between LAI and Standardised Precipitation Evapotranspiration Index (SPEI), as well as analysis of the temporal non-stationarity in the LAI trends and vegetation response to climate. Our results show mean LAI over the region increased at a rate of about 4 × 10−3 units per year, while the rate of increase for annual mean temperature was 0.035 °C per year. Annual precipitation did not show significant t...
Hydrology and Earth System Sciences Discussions, 2016
Vegetation plays a key role in the global climate system via modification of the water and energy... more Vegetation plays a key role in the global climate system via modification of the water and energy balance. Its coupling to climate is therefore important particularly in the tropics, where severe climate change impacts are expected. Vegetation growth is mutually controlled by temperature and water availability while it modifies regional climate through latent heat flux and changes in albedo. Consequently, understanding how projected climate change will impact vegetation and the forcing of vegetation on climate for various land cover types in East Africa is vital. This study provides an assessment of the vegetation trends in East Africa using Leaf Area Index (LAI) time series for the period 1982 to 2011, lead/lag correlation analysis between LAI and climate, a statistical estimation of vegetation feedback on climate using lagged covariance ratios as well as spatial regression analysis. Our results show few significant changes in current LAI trends though persistent declining vegetati...
Vegetation plays a key role in the global climate system via modification of the water and energy... more Vegetation plays a key role in the global climate system via modification of the water and energy balance. Its coupling to climate is therefore important particularly in the tropics, where severe climate change impacts are expected. 10 Vegetation growth is mutually controlled by temperature and water availability while it modifies regional climate through latent heat flux and changes in albedo. Consequently, understanding how projected climate change will impact vegetation and the forcing of vegetation on climate for various land cover types in East Africa is vital. This study provides an assessment of the vegetation trends in East Africa using Leaf Area Index (LAI) time series for the period 1982 to 2011, lead/lag correlation analysis between LAI and climate, a statistical estimation of vegetation feedback on climate using lagged 15 covariance ratios as well as spatial regression analysis. Our results show few significant changes in current LAI trends though persistent declining vegetation trends are shown from Southern Ethiopia extending through Central Kenya into Central Tanzania. Precipitation (temperature) exerts widespread positive (negative) forcing on lagging vegetation except in forests. Positive correlations between the lagging Antecedent Precipitation Index (API) and LAI were dominant compared to temperature. Positive vegetation feedback on precipitation dominates across the region while a stronger negative forcing is 20 exerted on Tmin compared to Tmax. Spatial dependence was also shown as a key component in the vegetation-climate interactions in the region. Given the vital role of land surface dynamics on local and regional climate, these results provide a valuable point of reference for evaluating the land-atmosphere coupling in the region.
The parameter uncertainty in hydrological modelling has been accorded much attention in the recen... more The parameter uncertainty in hydrological modelling has been accorded much attention in the recent past. Parameter uncertainty is a major source of overall model unreliability. In this study, the HydroPSO R package was used to assess parameter identification and uncertainty for the Soil and Water Assessment Tool (SWAT) model applied in the upper reaches of Nzoia River Basin. Fourteen parameters were selected based on previous studies and parameter sensitivity analysis using the Latin Hypercube Sampling method.
A pandemia causada pelo coronavírus (COVID-19/SARS-Cov-2) tornou-se um problema mundial, afetando... more A pandemia causada pelo coronavírus (COVID-19/SARS-Cov-2) tornou-se um problema mundial, afetando inúmeros setores essenciais, incluindo o educacional, impossibilitando aos alunos irem à escola para estudar e fazendo com que mantivessem um distanciamento social em casa. Como uma das formas de conter o avanço da pandemia, as escolas foram fechadas entre março e abril de 2020. A secretaria de Educação do Estado de Goiás, com o intuito de garantir a continuação do ensino, propôs a implantação do Regime de Aulas Não Presenciais (REANP), no qual a escolaridade foi transferida para a casa dos alunos, e as interações entre docentes e discentes estabeleceram-se por meio da utilização de mídias de ensino à distância. Tendo em vista o desafio da migração do sistema educacional presencial para o online, este estudo objetivou explorar as percepções dos alunos do Centro de Educação em Período Integral Dom Veloso-CEPI Dom Veloso, situado na cidade de Itumbiara-GO, frente a aprendizagem remota em tempos de pandemia. A pesquisa foi de caráter quali-quantitativo, e a coleta de dados realizada por meio de aplicação de questionário anônimo, estruturado e autoaplicável, este subdividido em categorias, sendo elas: características gerais, percepção do aluno quanto ao REANP, tecnologias inclusivas e questões direcionadas ao ensino médio quanto à escolha de profissão. O questionário foi respondido entre os dias 09 a 16 de setembro de 2020 por 7 turmas do Ensino Fundamental II e 6 de Ensino Médio, totalizando 118 participantes. A análise dos dados foi realizada por estatística descritiva e processados em planilha eletrônica, de onde foram retiradas as categorias e subcategorias mais significativas por percentuais. As respostas subjetivas foram consideradas em sua totalidade como indicadores para a realização de futuras propostas pedagógicas. Esta pesquisa contribui com a literatura de colaboração online entre escola, comunidade, professores, responsáveis e alunos, pois possibilita analisar como tem sido o processo de transição do ensino presencial para o meio virtual e as ações que mais impactam no sucesso da aprendizagem dos alunos, evidenciando ainda, uma forte tendência das novas tecnologias serem utilizadas como ferramentas perenes no processo de ensino-aprendizagem.
.................................................................................................... more .................................................................................................................. xvi CHAPTER ONE ..............................................................................................................
Scientific literature on the assessment and projection of climate change impacts suggests that th... more Scientific literature on the assessment and projection of climate change impacts suggests that the rapidly changing climate conditions are causing far-reaching consequences on natural resources and agricultural production. Atmospheric general circulation models (GCMs) have been widely used to simulate the present climate and to predict future climatic change at the global-scale. However, the assessment and projection of climate change at regional and national scales requires high resolution and consistent climate data to ensure that the scale and accuracy of results will enable planning for adaptation. This data can be obtained by downscaling the simulated output from GCMs using the appropriate predictors. However, this process is characterized by uncertainty due projections generated with multiple GCMs. This paper provides a summary of research developments in the use of GCMs for the assessment and projection of climate change impacts. The different techniques which have been used ...
<p&amp... more <p>Effective modeling of surface water and energy balance is crucial in planning and management of regional resources. However, the heterogeneous and clumped vegetation structure controls the portioning of land surface water and energy fluxes, which leads to large variations of local radiative and hydrological processes. The aim of this study is to characterize the land surface heterogeneity in East Africa and examine the impact of the spatially and temporally varying vegetation parameters on energy and water balance in the region.  We used MODIS datasets on Leaf Area Index (LAI), Enhanced Vegetation Index (EVI) and albedo to derive time-varying vegetation parameters for the period 2001 – 2011 period at 0.05° resolution. These parameters were integrated with the Variable Infiltration Capacity (VIC) model to characterize the effects of varying vegetation properties on surface water and energy fluxes. A twin simulation was also carried based on seasonally averaged vegetation parameters to isolate the effects of time-varying and spatially heterogeneous parameters on the water and energy fluxes. The simulation results were compared to rigorously validated global datasets on evapotranspiration and sensible heat. Results showed that the time-varying and spatially heterogeneous vegetation parameters provided surface water and energy fluxes which were more consistent with the validation datasets. The simulated evapotranspiration matched reasonably well with the observed values particularly in areas characterized by sparse vegetation and which are more prone to human influence. The improvements were highly noticeable in grassland and savanna land cover types. However, due to intensive human activities in region which affect not only the lad cover but also the vegetation structure, there is need for characterization of the land cover parameters based on high resolution data which can better capture the land surface heterogeneity in the region.</p>
Vegetation plays a key role in the global climate system via modification of the water and energy... more Vegetation plays a key role in the global climate system via modification of the water and energy balance. Its coupling to climate is therefore important, particularly in the tropics where severe climate change impacts are expected. Consequently, understanding vegetation dynamics and response to present and projected climatic conditions for various land cover types in East Africa is vital. This study provides an assessment of the vegetation trends in East Africa using Leaf Area Index (LAI) time series for the period 1982 to 2011, regression analysis between LAI and Standardised Precipitation Evapotranspiration Index (SPEI), as well as analysis of the temporal non-stationarity in the LAI trends and vegetation response to climate. Our results show mean LAI over the region increased at a rate of about 4 × 10−3 units per year, while the rate of increase for annual mean temperature was 0.035 °C per year. Annual precipitation did not show significant t...
Hydrology and Earth System Sciences Discussions, 2016
Vegetation plays a key role in the global climate system via modification of the water and energy... more Vegetation plays a key role in the global climate system via modification of the water and energy balance. Its coupling to climate is therefore important particularly in the tropics, where severe climate change impacts are expected. Vegetation growth is mutually controlled by temperature and water availability while it modifies regional climate through latent heat flux and changes in albedo. Consequently, understanding how projected climate change will impact vegetation and the forcing of vegetation on climate for various land cover types in East Africa is vital. This study provides an assessment of the vegetation trends in East Africa using Leaf Area Index (LAI) time series for the period 1982 to 2011, lead/lag correlation analysis between LAI and climate, a statistical estimation of vegetation feedback on climate using lagged covariance ratios as well as spatial regression analysis. Our results show few significant changes in current LAI trends though persistent declining vegetati...
Uploads
Papers by John Musau