Elsevier

Cities

Volume 107, December 2020, 102876
Cities

On the absurdity of rapid urbanization: Spatio-temporal analysis of land-use changes in Morogoro, Tanzania

https://doi.org/10.1016/j.cities.2020.102876Get rights and content

Highlights

  • This paper questions the increasing focus on population growth in Africa urbanization discourse

  • It analyzes spatial extent of urbanization to underscore the relatively faster spatial expansion of cities compared to population increase

  • It provides an understanding of the influence of urbanization on LULC changes

  • It presents implications of urbanization on urban planning and management

Abstract

This study questions the frequent overemphasis on population growth aspects of African urbanization with little consideration of the spatial extent by analyzing the influence of population growth on the spatial expansion of the Morogoro urban municipality (MUM) in Tanzania between 2000 and 2016. Shannon's Entropy, a random forest supervised classifier, and spatial analysis were adopted to analyze Multi-temporal Landsat images obtained through the Google Earth Engine platform to quantify the spatial and temporal distribution and pattern of land-use change. Findings from this research show that Shannon's entropy values for MUM increased from 0.522 in 2000, to 0.761 in 2007, and to 0.901 in 2016 with the urban land cover recording a considerable and consistent increase. Similarly, the municipality's annual rate of change in population decreased from 4.17% in 1967 to 3.81% in 2016, and is estimated to rise to 4.54% by 2030 with a corresponding population of 25,262 in 1967 and 622,000 in 2016. From the results, the rate of population growth is not commensurate with the rate of spatial expansion, as the spatial extent is more than twice the population growth. An important contribution from this research relates to the limited attention to the faster rate of urban expansion compared to population growth in African cities; a situation that is inconsistent with sustainable and resilient urban futures. It is recommended that municipal authorities should consider initiatives (e.g., environmental planning models) to reverse the current trend of urban growth in order to improve the health, density, sustainability and resilience of the urban environment.

Introduction

Rapid urbanization is one of the most challenging problems and fastest compounding task confronting cities in Sub-Saharan Africa (Cobbinah et al., 2015). While it is commonly perceived that urbanization exists primarily in the context of increasing population concentration in urban areas, this paper explores the spatial extent of the urbanization discourse, and argues that the extent of spatial expansion in urbanizing cities in many African countries are inconsequential with population growth. Recent research on African urbanization (Chai and Seto, 2019a, Chai and Seto, 2019b; Korah et al., 2019a; Korah et al., 2019b; Xu et al., 2019d) indicates that cities are already sprawling due to unplanned urban expansion characterized by, inter alia, rural-urban migration, natural population increase, and the presence of weak urban planning regimes. While in developed countries, urban growth has traditionally served as an engine for economic growth and industrialization, the situation in the developing countries in Africa is different as the process is poverty-driven, premature, and often described as abnormal (Cobbinah and Adams, 2018; Obeng-Odoom, 2010). Yet, it is estimated that by 2100, the largest metropolises on earth will include African cities such as Lagos (Nigeria), Kinshasa (DR Congo) and Dar es Salaam (Tanzania) (see Cobbinah, 2015).

Within the foregoing context, it is not surprising that unplanned but rapid urban population growth remains one of the major development issues confronting the African continent (Chai and Seto, 2019a, Chai and Seto, 2019b; Cobbinah et al., 2019). Urban population growth is rapidly changing the geography of towns and cities in Africa and other developing countries, with an understanding that rapid urban population growth is driving urban expansion. However, in many African countries, the mechanisms for ensuring effective urban management are generally weak (Cobbinah, 2015; Xu, Dong et al., 2019), and land supply for natural environmental resources such as urban forest and urban agriculture suffer considerably (Jiao et al., 2017; Keeratikasikorn, 2018; Xu et al., 2019d). For example, Korah et al. (2017) show rapid depletion of urban natural environmental resources due to the quick and unplanned urban population growth, and weak political commitment towards managing urbanization in Ghana. Further, several studies have demonstrated how rapid urban population is intensively changing the urban morphology and threatening important urban ecosystem services in Africa and elsewhere (Brandt et al., 2018; Gong et al., 2018; Qin et al., 2017). But the question remains: is rapid population growth commensurate with urban expansion?

This paper makes an important contribution to the knowledge on African urbanization as it demonstrates the unparalleled relationship between spatial expansion and urban population growth, and explores the design of sustainable and resilient solutions for addressing the urban challenge. There are increasing case studies reporting on rapid urban growth in African cities ((Cobbinah, 2017)Knauer et al., 2017; Korah et al., 2019a), yet little is known about the difference between population growth and spatial expansion. Using the Morogoro municipality in Tanzania as a case study, this paper analyzes the spatio-temporal patterns to appreciate the influence of change on the morphology of the municipality. Specifically, this study has three objectives: (i) to analyze the spatial-temporal land-use changes to determine the extent of spatial expansion between 2000 and 2016; (ii) to understand the complexity of variable interaction to produce land-use changes; and, (iii) to evaluate the urban planning implications of unplanned urban growth in the study area.

Shannon's Entropy, a random forest supervised classifier, and spatial analysis were adopted to analyze multi-temporal Landsat images to quantify the spatial and temporal distribution and pattern of urban land-use change in order to provide current, timing and reliable information to the municipal authorities and decision-makers. The analysis is organized into six sections. Section 1 provides the conceptual background of the study for urban growth and sustainable development. Section 2 describes the conceptual understandings of urban population growth and spatio-temporal analysis. Section 3 presents a case study setting and examines the research methodology used. Section 4 presents the findings of the research. Section 5 discusses the findings, and finally, Section 6 provides some concluding remarks of the paper.

Section snippets

African urbanization: conceptual understandings

Literature on urbanization indicates that there is dichotomy in the manifestation of urbanization across the developed and the developing countries (Cobbinah et al., 2015; Knauer et al., 2017; Korah et al., 2019a; United Nations, 2015). While urbanization in Europe and America was linked to industrialization attracting factory workers and businessmen subsequently leading to sprawling of cities into suburban areas, many developing countries are characterized by rapid urbanization but

Study context

As illustrated in Fig. 1, this study focused on the Morogoro Urban Municipality (MUM), which has 28 Wards (URT, 2016). A Ward is the smallest political unit delineated for the purpose of elections and political representation, and is represented by an elected Councilor. The MUM is located between 37°34′ and 37°45’east and 6°37′ and 6°55′ south and covers an area of 540 km2 (Fig. 1). The 2016 population and housing census report puts the MUM population at 359,670 (URT, 2016) (see Table 1). An

Land use transformation in the Morogoro urban municipality (MUM)

To map urban spatial expansion described in Section 3.2, seven land cover categories were identified: agriculture (farm work, gardening, horticulture), water (river, open water, dam, ponds, lakes), built up (residential, buildings, industrial, paved surfaces), woodland (closed and open woodland), bare land (open land, rock outcrops), wetland (swamps, sopping land, marshes) and forest (humid montane, lowland, mangrove, plantation). Fig. 3(a) shows land-use transformation across the three study

Discussion and policy implications

Recent and ongoing urban trends indicate that the management of population growth and spatial development remains a critical pathway towards sustainable development worldwide (Chai and Seto, 2019a; Chen et al., 2017; Tong and Feng, 2019). This is particularly critical for African cities where the urban population growth is occurring without industrialization (Cobbinah and Darkwah, 2017). Interestingly, findings from this study confirm those of previous research as urban growth in MUM is somehow

Conclusion

This study has explored the influence of population growth and the spatial extent on the Morogoro municipality in Tanzania between 2000 and 2016. It has also verified the effectiveness of emerging technologies in supporting the planning and management of urban growth in Morogoro using multi-temporal Landsat and a random forest classifier algorithm through the Google Earth Engine platform. Findings from this research indicate that although the Morogoro Urban Municipality has experienced an

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgment

The authors are grateful to the editor and the anonymous reviewers for their valuable suggestions and comments that helped improve this paper. This work was supported by the National Natural Science Foundation of China [Grants Number 41771452, 41771454 and 41890820], and the Natural Science Fund of Hubei Province in China [Grant Number 2018CFA007].

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