资源环境科技发展态势分析平台

Urban population growth and expansion of settlement areas are among the major challenges that African cities are facing. Addis Ababa's settlement area has been expanding into the city's peripheral area at the expense of losing green infrastructure (GI) of farmland and vegetated areas. The protection of GI is impeded by the lack of foresight information and tools to support urban planning. Therefore, a GIS-based urban spatial scenario design model (USSDM) was applied for modelling the settlement expansion in Addis Ababa. A business as usual scenario (BAU) and a densification scenario (DENS) were modelled to evaluate the impact of population density on the green infrastructure and the implications of excluding settlement development from flood prone areas. Training and workshops were conducted on the use of USSDM in the Addis Ababa master plan review. The results of our study indicated that increasing population density from 166 to 350 inhabitants per hectare would almost halve the losses of the green infrastructure. Moreover, the settlement development in the densification scenario would be located closer to the vicinity of the built-up area rather than spreading along the eastern part of the city, which is currently occupied by farmland in the case of BAU. Densification would also slow down expansion of settlements in river corridors but might expose more inhabitants to flood hazards. USSDM is one of few models in Africa that is designed towards application by urban planners as a tool of assessing the impact of urban development strategies on the surrounding environment.