Monitoring urban sprawl using remote sensing and landscape metrics. The case of sidi bel abbes, Algeria

Abstract

In Algeria, the advance of the urban front towards the peri-urban area has been confirmed since the 1970s and today takes several forms, in particular peri-urbanisation, a new form of urban sprawl that is generating an unprecedented consumption of peri-urban land. Sidi Bel Abbès, which occupies a strategic position in the north-west of Algeria in terms of population and economic activity, is undergoing a remarkable transformation of its urban space, especially its outskirts. In order to assess this phenomenon, we thought it worthwhile to explore a suitable spatial analysis method to highlight the inconsistencies of peri-urban dynamics and to monitor spatially, quantitatively and qualitatively the consumption of land by artificial surfaces. To do this, we used high spatial resolution remote sensing and landscape metrics to characterise spatial forms and track urban expansion at scale, methods that have profoundly changed traditional methods of spatial analysis and management. the results obtained show that in 1987 the urban area of the city of Sidi Bel Abbès occupied a surface of 972.81 ha, while in 2022 the surface occupied by built-up areas amounted to 2,842.91 ha, out of a total surface of 7,054 ha, representing an increase of 1,870.1 ha over the last thirty-five years. The analysis of spatial metrics illustrates the transition from a phase of accelerated landscape fragmentation to one of continuous expansion of existing urbanisation. This expansion is the result of a high growth rate, which would correspond well to the population evolution observed during this period. The increase in built-up area reflects the changing housing needs of the population. This urban dynamic is supported by the unrestricted expansion of the outskirts of Sidi Bel Abbès