Analysis of urban horizontal expansion and its impact on the surrounding land using GIS and remote sensing: a case of Werabe town

Abstract Nowadays, urbanization becomes the widest spreading and expanding event in the world. The issue of urbanization is one of the most important threats for developing countries like Ethiopia. Werabe town, which is found in southern and central parts of the country specifically in the Silte zone south nation nationality people (SNNP) region, is one of the rapidly growing towns at the moment. Therefore, this research is intended to assess the horizontal expansion of the urban and its impact on the use of the surrounding land in Werabe town using a Geographic Information System and integrating socio-economic data. To do this, a Land sat 8 satellite image was used to generate the change detection analysis and all the relevant primary data were gathered. After all, supervised image classification algorithms were applied to determine the available land use types by integrating socio-economic information. Finally, accuracy assessments were done to crosscheck whether the features are accurately classified in the Arc GIS. Based on this, in Werabe town built-up land was increased from 1963.98 ha (12.5%) in 2009 to 5251, 95 (33.4%) in 2019. Hence, in the study period built-up area was increased by 3287.97ha (20.9%). The forest cover of the study area in 2009 was 3798.27 ha (24.2%), however, it was decreased to 1358.01ha (8.6%) in the year 2019. Thus 2440.17 ha (15.6%) forest cover was deforested. For agricultural activity, 8833.41 ha (56.2%) of land was used in the year 2009 but it was altered to 7198.83 ha (45.7%) in the year 2019. Hence from 2009-2019, agricultural land was decreased by 1634.58 ha (10.5%). Bare land cover in 2009 was 1130.85 ha (7.2%) but it increased by 786.87 (5%) and became 1917.72 ha (12.2%) in the 2019 year. The study evidences that, urban built-up activity is expanding to all the surrounding landmasses, especially it is invading agriculture and forest cover lands of the peri-urban areas. Therefore, to prevent the loss of fertile lands against the ongoing expansion of urban areas, the integration of remote sensing and GIS with appropriate urban land management policy is vital.