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Typology of the evolution of macrocephaly by country in SSA (1960-2010): (a) graph, (b) map: groups or countries are ordered according to the macrocephaly in 2010; triangles are indicating whether the global trend increases or decreases since 1950. (Data source: United Nations Population Division, 2014).
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Since 1960, urbanization in Sub-Saharan Africa (SSA) has been rapid. While consistent demographic statistics now exist on urban population growth rates, these data have not been fully exploited to improve our understanding of the evolution of urbanization at the continental scale. We investigate urban change between 1950 and 2010 across SSA using c...
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... Several researchers use high-and moderate-resolution satellite images to study urban sprawl right now (Gidey et al. 2023a;Forget et al. 2021;Kabanda 2022;Satterthwaite 2017;Wolff et al. 2020), such as optical Landsat, Sentinel-2, Worldview, Satellite Pour observation de la Terre (SPOT) 5, and RapidEye, to name a few. Because it is a cause for concern that the pattern of land use has changed both within and beyond the city area (Ghosh et al. 2023), in this context, researchers use each image's spectral bands to align objects that exhibit comparable spectral responses and signatures with each feature. ...
Over half of the world’s population resides in urban areas. We anticipate that this pattern will become more evident, notably in South Africa. Therefore, research on urban spirals, both past and projected, is necessary for efficient urban land use planning and management. This study aims to assess the spatio-temporal urban sprawl dynamics from 2003 to 2033 in Mbombela, South Africa. We employed robust approaches such as machine learning, the cellular automata-Markov chain, and the Shannon entropy model to look at how urban sprawl changes over time using both the Landsat 4–5 Thematic Mapper and the 8 Operational Land Imagers. We conducted this study to bridge the gaps in existing research, which primarily focuses on past and current urban growth trends rather than future trends. The findings indicated that the coverage of built-up areas and vegetation has expanded by 1.98 km² and 13.23 km² between the years 2003 and 2023. On the other hand, the amount of land continues to decrease by -12.56 km² and − 2.65 km² annually, respectively. We anticipate an increase in the built-up area and vegetation to a total of 7.60 km² and 0.57 km², respectively, by the year 2033. We anticipate a total annual decline of -7.78 km² and − 0.39 km² in water bodies and open land coverage, respectively. This work has the potential to assist planners and policymakers in improving sustainable urban land-use planning.
... Thus, how well cities are governed will determine our ability to address global risks (Dilley, 2005). Countries in Asia and Africa are in the midst of a transition from predominantly rural to urban living, resulting in diverse urban growth patterns (Wolff et al., 2020). Challenges of rapid urban growth include health risks in slums (Oppong et al., 2015), environmental hazards, urban management, and agricultural land-use change (Marrengane & Croese, 2021). ...
Climate change increasingly prompts research on interrelated risks. This study analyzed research on East Africa and multiple risks. A literature review was conducted using bibliometric analysis with the VOSviewer tool and Web of Science. The main findings are that for many countries in East Africa, studies are absent, even on single risk assessments. Overall, multi-risk assessments that analyze hazard and impact chains are missing. Only a few cities have received scientific attention at the city level. In some cities, daily health risks predominate, while other cities have multiple studies about particular natural hazards. The highest casualties in the region are recorded for droughts and epidemics. The implications of the findings entail the need for more interconnected research of a) daily and low probability risks and b) hazards and impact chains, across regions and sectors. In addition, more research is needed in certain scientific disciplines. The findings can help scientists as well as policymakers identify research blind spots as well as research-rich samples for further studies. This will be important for comparing regions, countries, or cities in East Africa in global assessments or science policy reports.
... Yet there is no consensus among scholars regarding the spatial structure of African cities (e.g., Agyemang et al., 2019;Korah et al., 2018;Oduro et al., 2014). Others have also explored the challenges, drivers, and prospects of urbanization (Cohen, 2004(Cohen, , p. 2006Roberts & Hohmann, 2014;Wolff et al., 2020) or the consequences of urbanization for urban planning and governance (Cobbinah & Erdiaw-Kwasie, 2018;Korah et al., 2020) as well as the impacts on land-use and agricultural livelihoods (e.g., Kuusaana & Eledi, 2015). However, urban scholarship has often paid little attention to secondary cities, although they constitute the continent's main centers and drivers of urban transition. ...
Urbanization induced growth of secondary cities presents several issues and challenges for sustainable development. Yet, secondary cities continue to receive less attention from scholars, city planners and policymakers in Africa. Understanding the spatial and temporal dynamics of secondary cities is critical for achieving Sustainable Development Goal 11. This paper examines the emerging spatial and temporal evolution of two secondary cities in Northern Ghana. The paper utilizes raster data (1990-2019) and applied landscape metrics to analyze spatial development in Wa and Bolgatanga municipalities along three concentric rings. The results show significant increase in built areas over the study period. Urban development in the two cities is becoming more or less fragmented, dispersed and contiguous. Inadequate spatial planning, weakly regulated development and uncoordi-nated land markets account for the fragmentated spatial forms. The two cities exhibit a monocentric form that fluctuates, is dynamic, and discontin-uous. The paper reflects on the implications of the findings and suggests the need for a planned extension of secondary cities in Africa to generate efficient urban forms, curtail sprawl and protect the natural environment.
... The data were cleaned and coded using SPSS software. A k-means clustering approach was used to identify the emerging segments from the data as per Wolff et al. (2020) and Mittelmeier et al. (2019). In the analysis, a two-stage clustering approach was used to determine the appropriate number of clusters (using hierarchical analysis). ...
Our paper investigates how the heterogeneous structure of the middle class in sub-Saharan Africa influences its consumption of financial services, identifying drivers for their selection of these services. Implications for marketing practice are outlined. This research is an across-country city-based exploratory study in ten cities where structured questionnaires were used in interviews to obtain information from respondents over a period of 2 years. Our findings identify the importance of the financial realities of the three middle-class groups of the Accomplished, Comfortable and Vulnerable on their consumption of financial services and answer the question of what drives demand for these services. The three groups have varied spending and saving habits, perceptions of financial services and financial aspirations. We identify six key drivers for selecting services, namely availability, accessibility, affordability, status, security and trust. Technology is a key mediating variable of the marketing mix considerations. Marketing practice implications indicated a need for marketers to recognise the importance of the heterogeneity of the middle class and its influence on segmentation strategies. Opportunities for new approaches to new product development and marketing communication strategies that leverage the heterogeneity of the middle class are outlined. Marketers should also consider the varied influence of the drivers for the choice of financial services among the three groups. Our findings reinforce the need and potential that exist for financial services providers to improve the financial inclusion of previously marginalised consumers.
... In Africa, twofifths of people are already living in secondary urban areas with populations of less than 25,000 people (Zimmer et al. 2020). Despite the importance of these secondary and tertiary urban areas, much of the knowledge about urbanization processes and their implications for African food systems come from studies of large cities (McCall 1955;Fox 2012;Wolff et al. 2019). ...
Urban populations globally are expected to increase by approximately 2.5 billion by 2050. Much of this growth is taking place in African cities, where about 40% of Africans live in urban areas with populations of less than 250,000. In many of these cities, rapid urban growth has outpaced economic and social development, resulting in high levels of urban poverty and widespread food insecurity. As one response strategy, urban households may leverage their linkages with rural areas and other towns or cities to supplement their food consumption, for example through food remittances or food purchases from remote retailers. While this strategy has been found to occur among inhabitants of large cities where existing research on urban food systems and urban food linkages with other areas has focused, the dynamics in smaller cities are likely different. In this paper, we draw on data from 837 surveys collected in 2021 to investigate household food sourcing strategies across 14 urban areas in Zambia with populations less than 100,000. We find that rural-urban food linkages are dominated by grains while urban-urban food linkages are predominantly composed of higher value foods. Our data further suggest that urban area characteristics explain more of the variability in food sourcing behaviors than household level characteristics, and that urban food purchasing preferences in secondary urban areas are sensitive to the food retail landscape available to households. These relationships highlight the disparate role that rural and urban linkages play across cities of different sizes. They suggest a need for food-related policies to consider diverse urban food systems among smaller cities.
... In larger countries with a number of competing cities, the relative attraction of a city would then go down and rural migration would shift to other cities (Beck, 2012;Castells-Quintana, 2017;Wolff et al., 2020). But in smaller countries with few cities, this shift is hindered. ...
... But in smaller countries with few cities, this shift is hindered. Meanwhile the push of rural migration continues and natural population growth only goes down very slow (Gross and Ouyang, 2021;Varis, 2006;Wolff et al., 2020). ...
Cities in developing countries struggle with providing good waste collection services to all their citizens. Daily practice mostly shows low service coverage, especially in the poorer parts of cities. Up until now, research has mainly dealt with the symptoms of poor performance. This article aims at designing a qualitative System Dynamics model of the urban system that may serve as a diagnostic tool to find the root causes and leverage points for interventions. The research presented here uses a broad literature review to draw up a complex causal loop diagram describing all relevant urban variables (demographic, economic, social, financial, technical and governance-related) and their relations. The diagram is analysed using qualitative methods, partly derived from graph theory. It results in an evaluation of all variables, paths, loops and branches of the model, and finally in a simplified model. This simplified model is helpful in diagnosing waste management problems in cities, in formulating interventions and their points of leverage and even in formulating a new taxonomy that classifies cities with regard to the effect and delay in their urban processes. When it comes to interventions, the model suggests that the root cause is in populations growing faster than their economies, and that the enabling circumstances are mainly in poor governance practices that are unable to secure that tax incomes keep pace with needed budgets for sound services.
... The questionnaire and interview were administered using mobile devices and participants could choose to conduct the interview in their local language because the field workers were required to be fluent in the local languages of the cities they covered (Oyeyemi et al. 2016) SPSS software was used to clean and code the quantitative data and a k-means clustering approach was used to identify the different income threshold segments that have been described earlier. This is a common approach used in other previous studies that focus on identifying heterogeneous segments using multiple variables (Wolff et al. 2020). The appropriate number of clusters was determined by a two-stage clustering approach which was followed by a k-means cluster analysis to segment the data into the number of emerging middle-class income groups from the broad $10-$23 bend and the outlier of the floating group which is the focus of this study. ...
This research reports on a cross-country based investigation of the floating middle class in Africa demonstrating how their behavior and structure influences the design of marketing mix strategies used by marketers. Questionnaires were used to collect data in ten African cities. Key findings include the importance of branding and core drivers for purchase such as durability, origin, popularity, affordability, and a unique circle of quality variables. Innovative adaptations for pricing, distribution and marketing communications are outlined to assist marketers develop appropriate context relevant strategies to target the floating middle class. The discussion also outlines theoretical and practical implications.
... Unprecedented rates of rural-urban migration and natural population increase in sub-Saharan Africa (SSA) have dramatically affected urban environments [1]. Low income housing has not kept up with population growth which has contributed to widely varying physical and socio-economic landscapes within cities where formal and informal settlements coexist [2]. ...
Background:
The rapid and often uncontrolled rural-urban migration in Sub-Saharan Africa is transforming urban landscapes expected to provide shelter for more than 50% of Africa's population by 2030. Consequently, the burden of malaria is increasingly affecting the urban population, while socio-economic inequalities within the urban settings are intensified. Few studies, relying mostly on moderate to high resolution datasets and standard predictive variables such as building and vegetation density, have tackled the topic of modeling intra-urban malaria at the city extent. In this research, we investigate the contribution of very-high-resolution satellite-derived land-use, land-cover and population information for modeling the spatial distribution of urban malaria prevalence across large spatial extents. As case studies, we apply our methods to two Sub-Saharan African cities, Kampala and Dar es Salaam.
Methods:
Openly accessible land-cover, land-use, population and OpenStreetMap data were employed to spatially model Plasmodium falciparum parasite rate standardized to the age group 2-10 years (PfPR2-10) in the two cities through the use of a Random Forest (RF) regressor. The RF models integrated physical and socio-economic information to predict PfPR2-10 across the urban landscape. Intra-urban population distribution maps were used to adjust the estimates according to the underlying population.
Results:
The results suggest that the spatial distribution of PfPR2-10 in both cities is diverse and highly variable across the urban fabric. Dense informal settlements exhibit a positive relationship with PfPR2-10 and hotspots of malaria prevalence were found near suitable vector breeding sites such as wetlands, marshes and riparian vegetation. In both cities, there is a clear separation of higher risk in informal settlements and lower risk in the more affluent neighborhoods. Additionally, areas associated with urban agriculture exhibit higher malaria prevalence values.
Conclusions:
The outcome of this research highlights that populations living in informal settlements show higher malaria prevalence compared to those in planned residential neighborhoods. This is due to (i) increased human exposure to vectors, (ii) increased vector density and (iii) a reduced capacity to cope with malaria burden. Since informal settlements are rapidly expanding every year and often house large parts of the urban population, this emphasizes the need for systematic and consistent malaria surveys in such areas. Finally, this study demonstrates the importance of remote sensing as an epidemiological tool for mapping urban malaria variations at large spatial extents, and for promoting evidence-based policy making and control efforts.
Existing empirical literature provides converging evidence that selective emigration enhances human capital accumulation in the world's poorest countries. However, the within-country distribution of such brain gain effects has received limited attention. Focusing on Senegal, we provide evidence that the brain gain mechanism primarily benefits the wealthiest regions that are internationally connected and have better access to education. Conversely, human capital responses are negligible in regions lacking international connectivity, and even negative in better connected regions with inadequate educational opportunities. These results extend to internal migration, implying that highly vulnerable populations are trapped in the least developed areas.
