Degradation Of Green Infrastructure In Addis Ababa,Ethiopia:Understanding Barriers,Spatio-Temporal Dynamics And Characteristics In Functional Urban Land Uses

Established in 1886,Addis Ababa,the capital city of Ethiopia,has grown from a small settlement to a dichotomous city with a blend of modern high-rise buildings and slum settlements over the past century.In recent years,with unprecedented urbanization characterized by large-scale informal settlement expansion has induced over exploitation natural resources,which amplified degradation of Green Infrastructure(GI).Although studies on GI degradation has been reported in a growing number of studies,its spatial variability in heterogeneous urban landscape and characteristics in built up functions have never been explored in sub-Saharan Africa cities.The objective of this study is to analyze the spatial-temporal dynamics of GI in Addis Ababa over the past three decades(19892019),understand barriers for its advancement and quantify composition and configuration in functional land use.The study employed Remote Sensing and GIS,FRAGSTATS,statistical analysis,Landscape Expansion Index(LEI)integrated with zonal and directional analysis.The study identified that GI was first introduced in 1935 during Italian occupation.For nearly eight decades,it had been hinged on park planning and has recently evolved to riverside retrofitting and water park development.Factors that limit its advancement are poor conceptualization,institutional,socio-cultural,resource and cognitive challenges,among which,institutional challenge is identified as foremost one.Further,zonal analysis revealed that GI in the inner zone decreased from 60 ha to 54 ha(10%),from 54 ha to 38 ha(29.6%)in the first(1989-1999)and second periods(19992009),while it increased from 38 ha to 53 ha(39.4%)in the third period(2009-2019).Contrarily,the GI in the outer zone consistently decreased from 38,430 ha to 33,996 ha(11.5%),from 33,996 ha to 27,603 ha(18.8%),and from 27,60 ha to 20,677 ha(25.1%),with an increasing rate of decline 1.1%,1.8%,and 2.5%,respectively,reporting growing pressure on the peripheral GI’s.In addition,the directional analysis showed that GI predominately shrunk in SSE>SEE>SSW>SWW>NEE>NWW>NNW>and NNE directions,which aligns with the directions of urban expansion.Moreover,composition and configuration analysis revealed that low-density mixed residence,high-density mixed residence and medium-density mixed residence shared 42.6%,16.7%and 8.7%,of the GI,respectively,together occupying 68%of the total GI in functional urban land uses areas.While manufacturing and storage,social services,transportation,administration,municipal functions,and commercial areas contained 11.6%,8.2%,6.6%,3.3%,1.3%,and 1%of the GI,respectively;together account for only 32%of the GI,signifying that two-third of the GI was found in residential areas.Added to that,the study has shown that GI in medium density mixed residential areas are highly fragmented but less geometrically complex compared to high density mixed residential areas and low density mixed residential areas,which attributed to higher Building density(BD),and buildings coverage(BC),and a complex urban form.In conclusion,the pattern of GI dynamics markedly varies across urban landscape and portrayed a non uni-directional change,which correlates with urban development strategies pursued over the study period.City’s spatial expansion characterized by sprawling and dispersal resulted in formation of non-contiguous urban forms that influenced the spatial characteristics of GI and challenged effective implementation zoning regulation stipulated by the government.Over all,the findings provide scientific evidence for urban planners to adopt sustainable urban form design through improved urban planning intervention measures that integrates nature with built environment.Finally,it is recommended that addressing institutional,socio-cultural,resources,cognitive barriers;re-imagining GI planning and management system;formulating coherent and synonymous legislatives frameworks,controlling urban growth,promoting education on environment and GI,improving policy making process in Ethiopia is important to restore the degrading GI in land constrained Addis Ababa.