Unravelling the Frontiers of Urban Growth: Spatio-Temporal Dynamics of Land-Use Change and Urban Expansion in Greater Accra Metropolitan Area, Ghana

Abstract

This study analyzed and assessed spatio-temporal dynamics of land-use change (LUC) and urban expansion (UE) within the Greater Accra Metropolitan Area (GAMA) of Ghana. This region serves as a case to illustrate how a major economic hub and political core area is experiencing massive spatial transformations, resulting in uneven geographies of urban land expansion. Quickbird/Worldview-2 images for the years 2008 and 2017 were segmented and classified to produce LUC maps. LUC and UE were analyzed by post-classification change detection and spatial metrics, respectively. The results revealed an intensive decrease in open-space by 83.46 km2, brushland/farmland (194.29 km2) and waterbody/wetland (3.32 km2). Conversely, forestland and urban built-up area increased by 3.45 km2 and 277.62 km2. Urban extent expanded from 411.45 km2 (27%) in 2008 to 689.07 km2 (46%) in 2017 at a rate of 5.9% and an intensity of 2.06% with an expansion coefficient of 1.5%, indicating low-density urban sprawl. The spatial pattern turned out to be an uneven and spatially differentiated outward expansion, which materialized mainly in districts located within the urban peripheries but intensely towards eastern and western directions, being the frontier and the hotspots of urbanization. Overall, the findings bear important implications for regional spatial planning and development.

Impact of Land Use/Land Cover Change on Hydrological Components in Chongwe River Catchment

“…Understanding the impact of LULC change on watershed hydrology at catchment level could help to (i) identify and alleviate the occurrence of critical shifts in hydrologic processes, (ii) assess the water resources availability and their sustainable utilization under increasing population, agricultural expansion, and industrialization, and (iii) formulate appropriate policies to improve land use planning and spatial developments [8][9][10]. In this regard, direct field observations and spatial-temporal analysis of LULC change from remote sensing data play a crucial role in providing historical and current information to understand the effects on river ecosystem, guide urban densification and limit unsustainable urban expansion at catchment level [11][12][13].The Chongwe River Catchment, with a population of over 834,359 people, is a sub-catchment of the Zambezi River Basin [14,15], and has been experiencing changes in LULC influenced by the fast-growing population, infrastructure and social-economic developments particularly in Lusaka City [15][16][17]. About 45% of Lusaka City falls within the Chongwe River Catchment [16].…”

A Comparison of Satellite-Based Estimates of Urban Agglomeration Size for the Accra Area

“…Akubia and Bruns [17] reports an urban extent for Accra of 411 km 2 in 2008 and 689 km 2 in 2017 based on the analysis of Quickbird/Worldview-2 imagery. Although none of the analyzed maps in the current study reports the urban extension in 2008, it seems clear that both values are considerably lower than what is found by the examined studies, which may indicate a narrow definition of "urban" and/or, especially for 2017, the fact that the study area is confined within administrative boundaries.…”

“…Currently, a number of studies have presented city-wide land-cover maps of Accra based on medium-and high-resolution images (see [14][15][16][17][18] for recent examples). So far only a few studies have analyzed the challenges of comparing the maps resulting from different remote sensing-based studies.…”

Spatial Variation of Land Use/Cover Composition and Impact on Surface Urban Heat Island in a Tropical Sub-Saharan City of Accra, Ghana

“…Accra is known as the most urbanized area in Ghana with a large piece of Ghana's industrial establishments [22]. Hence, the Accra area undergoes accelerating population growth and expansion of the built up area [24]. The study area stretches 50 × 50 km 2 with a 25 km radius from the city center in the central business district.…”

“…The study area stretches 50 × 50 km 2 with a 25 km radius from the city center in the central business district. of the built up area [24]. The study area stretches 50 × 50 km 2 with a 25 km radius from the city center in the central business district.…”