Spatiotemporal analysis of urban expansion using GIS and remote sensing in Jigjiga town of Ethiopia

Abstract

Urban expansion necessitates proper planning to avoid profound negative environmental and socioeconomic impacts. The main objective of the study was to analyze the spatiotemporal changes that occurred in Jigjiga town in the last three decades. To meet the intended objectives, geographic information system (GIS) and remote sensing technologies were employed. The results of the study disclosed that urban expansion of Jigjiga town was largely caused by the increasing built-up area from 4.2% in 1985, 5.2% in 2005 to 24% in 2015 out of Jigjiga’s township area of 7492 ha due mainly to natural increase of the population, urban ward migration, and most recently, a change in status of the town from zonal capital to regional capital. This uncontrolled expansion towards peri-urban neighborhoods has exerted pressure on cropland and vegetation. Cropland has declined from 3836.6 ha (51.6% of Jigjiga’s township area of 7492 ha) in 1985 to 2486.0 ha (33.2%) in 2015. Areas covered by forest increased by 84.8 ha in the first decade (1985–1995) and by 218 ha in the second decade (1995–2005), but towards the last decade (2005–2015), about 231 ha of forestland was converted to built-up area. The decline of grassland especially in the southern part of the town and its surrounding rural area was also very significant. In the last three decades, about 463 ha of grassland was converted largely to built-up areas. Therefore, controlling and monitoring of urban expansion using GIS and remote sensing technologies are vital solutions to protect peri-urban neighborhoods from adverse effects of urbanization.