Analysis of land use/land cover changes and their causes using landsat data in hangar watershed, Abay basin, Ethiopia
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ORIGINAL ARTICLE
Analysis of land use/land cover changes and their causes using landsat data in hangar watershed, Abay basin, Ethiopia Abdata Wakjira Galata1 Received: 15 June 2020 / Revised: 11 August 2020 / Accepted: 12 August 2020 © Springer Nature Switzerland AG 2020
Abstract This study analyzed land use/land cover (LULC) changes and their causes for the last 30 years from 1987 to 2017, covering an area of about 7673.87 km2 in Hangar Watershed, Ethiopia. The LULC maps were produced from three Landsat images of 1987 (Landsat-5 TM), 2001 (Landsat-7 ETM+) and 2017 (Landsat-8 OLI_TIRS) through pixel-based supervised image classification. The results indicated that there were an expansion in cultivated land (by + 24%, + 6%, and + 28%) and builtup area (by + 22%, + 19%, and + 37%) for LULC of corresponding years 1987–2001, 2001–2017 and 1987–2017. Whereas, there was a decrease in the forest (by − 20%, − 15% and − 32%), rangeland (by − 28%, − 13% and − 37%), grassland (by − 65%, − 6% and − 67%) and water body (by − 2%, − 54% and − 55%) for LULC of 1987–2001, 2001–2017 and 1987–2017 correspondingly. The major causes of these changes were identified as population expansion associated with increasing agricultural expansion, big tree clearing for building and wood extraction for fuel. The extraction of wood for fuel and building should be limited and legally managed, awareness of land use/land cover change hazard should be given for the community so that they shift the trends of land use and land cover change towards increasing vegetation covers which in turn can balance sediment yield. Keywords Anthropic impact · Environmental changing · ERDAS imagine · Landsat images · Sediment yield
1 Introduction Land use/land cover (LULC) changes influence climate and weather conditions from local to global scales (Oki et al. 2013). The Land-use and Land cover conversion, such as from forest to various land-use types is a collective experience in most areas of Eastern African countries including Ethiopia, were ranked as the highest in Africa at a rate of 0.94% (1990–2000) and 0.97% per year (2000–2005) due to increasing human and livestock population in protected areas (Garedew et al. 2009). For example, in Ethiopia, the estimated forest area in 1955 was 17 million ha, but by 1979, it dropped dramatically to 3.4 million ha (Hailemariam et al. 2016). The growing human population is responsible for the Communicated by M. V. Alves Martins * Abdata Wakjira Galata [email protected]; [email protected] 1
Department of Hydraulic and Water Resources Engineering, Jimma University Institute of Technology, Jimma, Oromiya, Ethiopia
expansion of agricultural fields that has been one of the main modes for personal conversion and modification of the environment (Piao 2007). In Ethiopia, land use for human activities, such as agriculture, construction and urbanization, has been influenced by an increase in the human population in urban areas and the depopulation of rural areas (Hamza and Iyela 2012). However, the rural population is
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