Abstract
Long-term urban land use land cover change (LULCC) dynamics and climate change trends in Southwest Ethiopia's four urban centers were examined for 60 years. Remote sensing, aerial photos, and Landsat, temperature, and rainfall data were analyzed from a climate change perspective over the Jimma, Bedelle, Bonga, and Sokorru urban centers of southwest Ethiopia from 1953 to 2018. Based on geospatial analysis and maximum likelihood supervised image classification techniques to classify LULCC categories, the Mann-Kendall test was applied to perform trend analyses on temperature and rainfall. The LULCC analysis revealed that built-up areas over the urban centers had shown an increasing trend, with the highest increment by 2,360 hectares over Jimma, while vegetation, wetland, and cropland declined due to conversion of plain lands to built-up areas and other similar zones. The pronounced decline of vegetation coverage was 1,427, 185,116, and 32 hectares in Jimma, Bedelle, Bonga, and Sokorru, respectively. Mann-Kendall test results showed a significant sign of intra-seasonal and inter-annual variability of rainfall while the summer and annual rainfall patterns remained less variable compared to other seasons. This study's findings revealed that when the mean between the two climatic normals of 1953–86 is compared with 1987–2018, the temperature has significantly increased in the latter three decades. The rapid expansion of built-up areas coupled with a sharp decline of green space or vegetation and agricultural/croplands could lead to gradual changes in LULCC classes, which have contributed to the changing of the local climate, especially the surface temperature and rainfall over the urban centers of southwest Ethiopia. Therefore, we recommend that the local urban administrations emphasize sustainable urban development by integrating urban planning policies with land use to protect the environment by adopting local municipal adaptation and national climate change strategies. Restoration of the local environment and creation of climate-smart cities could be critical to the resilience of urban dwellers and ecosystems to the changing climate by enhancing grass-root climate services. To that end, we recommend further advanced research to understand how urban LULC-related changes and other factors contribute to local and regional climates, as urban areas of Southwest Ethiopia are undergoing a rapid transformation of their rural surroundings.
Highlights
Land use land cover (LULC) changes impact weather and climate, both on a local and global spatial scale, which calls for global consideration and continuous monitoring of the changes and subsequent predictions (Mengistie et al, 2013)
Four thematic LULC classes, built-up, vegetation, agriculture or cropland, and wetlands were generated for the years 1957, 1987, and 2018 using supervised image classification (Figure 2)
Our findings of a significant increase in built-up areas and a decrease in cropland, wetland, and vegetation in all urban centers under this study are consistent with the previous study as documented by Abebe et al (2019), which showed that increases in built-up areas resulted because of illegal settlement and transformation of land over the past two decades
Summary
Land use land cover (LULC) changes impact weather and climate, both on a local and global spatial scale, which calls for global consideration and continuous monitoring of the changes and subsequent predictions (Mengistie et al, 2013). IPCC (2014) documented that between 1906 and 2005, the global average surface temperature rose by 0.7◦C. This change occurred in two phases: from the 1910s to the 1940s, and more strongly from the 1970s to the present. The global urban area estimates, which vary from less than 1–3% of the world’s land surface to, are rapidly expanding in different parts of the world, leading to significant changes in other land use land cover types (Liu et al, 2014). Global climate change is induced by the LULC change because of the considerable effect urban expansion has on the environment, ecosystem, and society (Grimm et al, 2008; Wilson and Chakraborty, 2013)
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