Spatiotemporal Change of Urban Sprawl Patterns in Bamako District in Mali Based on Time Series Analysis

Moussa Aliou Keita,Ru An,Renzong Ruan

doi:10.3390/urbansci5010004

Abstract

For decades, urban sprawl has remained a major challenge for big cities in developing countries, such as Bamako. The aim of this study is to analyze urban sprawl pattern changes over time in the Bamako district using landscape index analyses. Four thematic maps of land cover (LC) were produced by applying the maximum likelihood supervised classification method on Landsat images for 1990, 2000, 2010, and 2018. Five landscape indexes were selected and calculated at class level and landscape level using FRAGSTATS software. The results showed that the dominant class for all the years within the landscape was a built-up class. Forest class covered the smallest area in terms of the percentage of land (%PLAND), and was the weakest class in terms of number of patches (NP) and largest patch index (LPI). Grassland is defined as the class with the highest fragmentation, farmland with the highest shape irregularity and more heterogeneity, and built-up with the highest patches. Class area (CA) of built-up showed the importance of sprawl in Communes 6, 5, and 4, respectively. Indices trends and land use/cover showed infill, scattered, and ribbon developments of sprawl. This study contributes toward monitoring long-term urban sprawl patterns using index analyses.

Highlights

Urbanization and urban development are keys toward global economic growth in the 21st century [1,2,3,4]
This study presents four landscape metric results at class level and four at landscape level, over a scale of eighteen years, which is further subdivided into four years (1990, 2000, 2010, and 2018)
The findings demonstrate the utility of remote sensing imageries and landscape metrics for analysis of urban environments

Summary

Introduction

Urbanization and urban development are keys toward global economic growth in the 21st century [1,2,3,4]. Urban sprawl pattern analysis has become an important field of research around the world, mainly in developing Asian countries where different aspects about urban sprawl were studied. While some studies have explored the economic, demographic, and natural implications of urban sprawl processes [6,7,8], others focused on political, environmental, and others aspects, such as the impacts [7,9,10]. In recent years, urban sprawl has been studied in China and India, more so than other places. Most of these studies, using different methods and approaches, found almost the same results concerning the causes, characteristics, and processes of urban sprawl. Urban pollutions, and natural hazards (e.g., flooding) are the main impacts of urban sprawl [16,17,18]

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Conclusion