Characterizing the urban environment through urban morphology types (UMTs) mapping and land surface cover analysis: the case of Addis Ababa, Ethiopia

Abstract

Characterizing the urban environment through urban morphology types (UMTs) can help to decide on what parts of urban areas should be conserved. The aim of this study was to map and detect changes in UMTs and land surface cover in the city of Addis Ababa. UMT maps for 2006 and 2011 were produced by digitizing ortho-rectified aerial photographs. Eleven higher level and 35 detailed UMTs were identified as the basis for the study. Within the defined higher levels of UMTs in 2006, the most dominant UMT was agriculture covering 38 % of the total area while in 2011 residential UMTs stand out with the highest land coverage (33.3 %) indicating rapid conversion of other land uses to residential category. Land surface cover analysis used 12 surface cover categories. Change analysis between 2006 and 2011 revealed that surface cover types of built structure type I (generally well planned and high rise buildings), non-eucalyptus trees, dark bare-ground, light bare-ground and vegetable farm showed positive change whereas built structure type II (informal, generally unplanned, and non-high rise buildings), eucalyptus trees, shrub/bush vegetation, grassland and field crop cover showed negative change. The results also showed that almost half of the land surface cover of Addis Ababa could be considered to be evapotranspiring. To maintain a balanced urban environment, all green spaces in the city should be ecologically networked and the planning of green space should aim to ensure that principles of multi-functionality are followed as the city continues to undergo rapid urbanization.