GIS-based multi‐criteria analysis for sustainable urban green spaces planning in emerging towns of Ethiopia: the case of Sululta town

Urban green spaces are important components, contributing in different ways to the quality of human well-being. In the planning and management of urban centres, attention to the appropriate site selection of urban green spaces with regard to the importance that these spaces have from the perspectives of ecology, socioeconomic, mentality, etc., is an inevitable requirement. In present decades, land suitability mapping methods and GIS have been used to support urban green space planners in developed countries; however, its application and practices are limited in developing countries, like Ethiopia. Therefore, the aim of this study has to select potential sites for green spaces in Sululta town that assist an effective planning process of green areas in a sustainable way.

Methods

In this study, GIS-based Multi-criteria analysis (MCA) has been adopted to select suitable sites for urban green spaces. Existing land use, proximity to settlement, road and water body, population density, land ownership, topography, and scenic attractiveness were recognized as the key factor affecting urban green land suitability.

Results

The results showed that 13.6%, 34%, 28%, and 18.9% of the study area are highly suitable, suitable, moderately suitable, and poorly suitable, respectively, for urban green spaces development. Furthermore, out of the total area of the study town 5.5% of the landmass is not suitable for urban green spaces development.

Conclusions

Therefore, the application of GIS-based MCA has provided an effective methodology to solve a complex decisional problem in urban green spaces site selection in the study town and urban planning all over the country.

Introduction

With more than 50 % of the global population now living in urban areas, the world has experienced unprecedented urban growth in recent decades (Wu 2014). The global urban population is projected to be 6.3 billion by 2050, almost double the global population of 3.5 billion urban dwellers in 2010 (SCBD 2012). This rapid urbanization has posed greater pressure on natural resources and the environment (Rees and Wackernagel 1996; Shi 2002) and the amount of land exploited for infrastructure development and buildings has increased at the expense of urban green spaces (Sandstrom 2002).

Urban green spaces are of crucial importance, especially in an urbanized world, as they are the key providers of ecosystem services and improve the quality of life of urban residents. For instance, by increasing water infiltration, it promotes the regulation of ecosystem services (Haase and Nuissl 2007; Pauleit and Duhme 2000) and has positive impacts on microclimate regulation (Gill et al. 2000; Hamada and Ohta 2010). It also provides benefits to city residents, such as exercise, socialization, interaction with nature and connection with places of rich cultural heritage (Crompton 2005; Cho et al. 2006; Sarev 2011). It is important to understand in this sense that green spaces are main components of urban environments (Tratalos et al. 2007) not only for their recreation but also for social contributions (Jones et al. 2013), health (Kimberlee et al. 2011) and environmental outcomes (Patel et al. 2009).

Despite the numerous aforementioned benefits, urban green spaces are unable to provide urban dwellers with the desirable facilities due to increased urbanization and unplanned urban growth (Wright and Nebel 2002), lack of proper site selection and planning and lack of attention to population thresholds (Ahmadi et al. 2016). As a result, both quality and quantity of urban green spaces are adversely affected and do not deliver what urban centres demand from urban green spaces as a living organism (Crompton 2001). Therefore, by taking into consideration environmental and social-economic factors, well planned, and well-designed green spaces within the reach of the community are mandatory in order to maximize the value that green spaces bring to urban residents and their environment in a sustainable way (Giles-Corti et al. 2005).

Land suitability analysis is vital in urban green spaces planning as it gives room for choosing the most suitable site from among various alternatives (Sahabo and Mohammed 2016). For suitable site selection, the multi-criteria analysis (MCA) approach that is integrated with the Geographical Information System (GIS) has been increasingly used (Uy and Nakagoshi 2008; Van Berkel et al. 2014; Ustaoglu, and Aydınoglu 2020). In order to determine different land problems considering the alternatives, MCA focuses on various parameters such as biophysical, socio-economic and policy-related factors in decision-making processes (Pramanik, 2016).

The MCA methods have been widely applied in both developed and developing countries to select agricultural sites, industrial sites, residential areas, landfill sites, wind farms, disaster area, health centres, and education centres (Rikalovic et al. 2014; Rahmati et al. 2016; Marsh et al. 2016; Demesouka et al. 2016; Vasileiou et al. 2017). However, the MCA methodology has not commonly used in developing countries such as Ethiopia to select suitable site for urban green spaces development and using MCA in urban planning, as decision-making tools are not practiced.

In parts of Europe, North America and Asia, MCA approach that is integrated with the GIS to identify suitable site for urban green spaces has been receiving more attention and it is considered as one of the essential tools for urban green spaces planning (Nowak et al. 2003; Ustaoglu and Aydinoglu 2020). In order to specifically analyse the characteristics of green areas and possible sites suitable for green spaces in either the European or overseas context, numerous studies were conducted (Kienast et al. 2012; La Rosa and Privitera 2013; Chandio et al. 2014; Morckel 2017; Merry et al. 2018; Ustaoglu and Aydınoglu 2020). However, in developing countries, while some green spaces studies have been performed, the available studies have concentrated largely on the evaluation of urban green spaces with less emphasis on the study of the suitability analysis for green spaces site selection. For instances, the studies in sub-Saharan African countries are primarily related to street trees’ abundance and composition (Kuruneri-Chitepo and Shackleton 2011), green space degradation (Mensah 2014), green space extent (McConnachie et al. 2008; McConnachie and Shackleton 2010) and planning aspects (Cilliers 2009; Fohlmeister et al. 2015).

This situation also occurs in the case of Ethiopia, which is one of the fastest growing countries in sub-Saharan Africa (Lamson-Hall et al. 2018), and studies have focused on the impacts of urban growth on green space (Abebe and Megento 2016; Gashu and Gebre-Egziabher 2018; Abo El Wafa et al. 2018), climate change adaptation (Lindley et al. 2015), the development of functional green infrastructure and ecosystem service (Woldegerima et al. 2017), planning aspect (Girma et al. 2019), green spaces depletion (Girma et al., 2019a) and utilization pattern (Yeshewazerf 2017; Molla et al. 2017; Girma et al. 2019b). However, the topic of suitability analysis for green space in the urban environment by using methods such as GIS-based Multi-criteria analysis has not discussed in these studies. This study therefore aimed to fill the existing research gap by applying GIS-based Multi-criteria analysis method to identify suitable sites for urban green space development in Sululta town.

Materials and methods

Description of the study area

Sululta town is located in Sululta district of the previous North Shewa administrative zone of Oromia region, currently under Oromia special zone surrounding Finfinne. It is situated very close to the district capital town Chancho and Addis Ababa, which are far about 15 and 23 km in the north and south direction, respectively. Astronomically, the study area is located between 9° 30′ 00″ N to 9° 12′ 15″ N latitude and 38° 42′ 0″ E to 38° 46′ 45″ E longitude. The administrative area of the town is about 4471 hectares. Sululta has the same general climatologically characteristics as that of Addis Ababa. Globally it is a part of tropical humid climatic region, which is characterized by warm temperature and high rainfall. The soils of the zone are basically derived from mesozoic sedimentary and volcanic rocks. The major soil types of Suluta area are Chromic Luvisols (Fig. 1).

figure 1

figure 2

Methods

Urban green spaces have continuously played a significant role in enhancing the quality of life of urban inhabitants and in supporting urban metabolism. However, urban green spaces have experienced a physical and social decline, while its heterogeneity and richness is often neglected and its contribution to the well-being of a community ignored within current urban planning instruments in Sululta town (Girma et al. 2019; Girma et al. 2019a). Under this circumstance, GIS-based multi-criteria land suitability analysis is becoming critical in determining the land resource that is suitable for urban green spaces (Cetin 2015). Continued development and refinement of suitability analysis, particularly with GIS technology, can enable urban planners to create a suitable urban green spaces system in the urban environment (Manlum 2003).

Several literatures have stated that MCA components are used in only a few GIS programs (e.g. IDRISI and ILWIS) to select appropriate places for different functions (Lesslie et al. 2008; Chen et al. 2001; Ozturk and Batuk 2011). MCA has not yet been implemented in the standard functions, according to the literatures, while ArcGIS is one of the most popular GIS applications. In this study, MCA has incorporated ArcGIS 10.2 as a method to select an appropriate location for the development of urban green space.

Therefore, this study proposed the application of GIS-based multi-criteria suitability analysis using analytical hierarchy process (AHP) to support the decision-making process on selecting an appropriate site for development urban green spaces. This approach will be used as a basis for the town’s administration and the planning authority to identify an appropriate and potential site for providing suitable, sufficient and accessible urban green spaces to the urban dwellers. Moreover, it will be used as a benchmark to guide the sustainable land use decision in the study area.

In this study, to select a suitable site for urban green spaces using GIS-based multi-criteria analysis the following five main steps were used:

Spatial and non‐spatial data collection

The primary data from the field survey were collected through interviews undertaken with different experts in the related field of study for identifying factors that are important for urban green spaces site selection. Various spatial data were also obtained from different secondary sources (Table 1). The data were analysed in ArcGIS 10.2 and ERDAS Imagine 2010 for further analysis and mapping purposes.

figure 3

According to the overall suitability map, southern, central and south eastern part of the study area is more adequate for urban green space such as playground, sport field, parks and the like development purposes. It is because the lands mass in this area are fall in suitable and highly suitable classes.

Based on Table 6, out of the total area of the Sululta, town, about 13.6 % (610.7 ha) area fall under the highly suitable category. The suitable area covers an area of 34 % (1523.9 ha) of Sululta town. The area which is shaded by blue colour covers 28 % (1276.6 ha) of Sululta town representing the moderately suitable class. Moreover, based on the Table 6, out of the total area 18.9 % (813 ha) of Sululta towns have been covered by poorly suitable class. Out of the total area 5.5 % of Sululta towns land mass is not suitable for urban green spaces.

Table 6 Area cover of classified land suitability map for Sululta town

The final suitability maps show a series of spaces following a pattern and connectivity. These can be adapted to form the urban green spaces system, complete with corridors and hubs within the study area. This can increase opportunities for residents and biodiversity to enjoy the nature and benefits of urban green spaces. Moreover, as the maps show the town have a high potential for developing the urban green spaces such as playground, sport field, parks and the like as more than half of the town’s lands mass are suitable. Therefore, the planning authority and the towns’ administration can take this approach as a benchmark to provide suitable, accessible, interconnected and sufficient urban green spaces in town under study.

Literature shows that many studies have used multi-criteria analysis based on GIS for land use planning in different countries. Ustaoglu and Aydinoglu (2020), for example, performed a site suitability study for the development of green space in the Pendik district of Turkey. Similar to this study, they considered geophysical factors, accessibility, blue and green amenities, settlement centres and land use/cover as the key factors affecting urban green land suitability and they also concluded that undertaking suitability analysis for green space through GIS based multi criteria analysis is mandatory for optimising land use planning and decision support. Giordano and Riedel (2008) conducted land suitability assessment of greenways in the city of Rio Claro, Brazil. They combined the AHP method with GIS for the analysis of land suitability, similar to this study. Uy and Nakagoshi (2008) used the ecological threshold factor approach and GIS in Hanoi, Vietnam, for land suitability study for green areas. Their research considered the concepts of landscape-ecology in the organisation of urban green spaces. Chandio et al. (2011) used GIS-integrated AHP strategy to evaluate factors such as land availability, land price/value, accessibility and socio-economic factors for the development of public parks in Larkana City, Pakistan. Similar to this study, Abebe and Megento (2017) also considered land use/cover, density, road network and river as the main factor undertake to site suitability analysis of urban green space development for the city of Addis Ababa.

In general, the factors used in this study to select suitable site for urban green spaces such as parks, play grounds and sport filed development is compliant with different studies undertaken in different part of the world. Moreover, similar to studies conducted by Giordano and Riedel (2008), Uy and Nakagoshi (2008), Chandio et al. (2011), Abebe and Megento (2017) and Ustaoglu and Aydinoglu (2020) the methodology applied in this study provide a base for future studies focusing on land suitability assessments. GIS-based multi criteria analysis suitability assessment technique can be utilised to produce land suitability maps regarding other land uses such as industrial, residential, landfill, urban land, water management and forest development. Moreover, the methodologies are complementary with the other green land assessment methods, such as landscape metrics analysis, landscape connectivity analysis, accessibility and network analysis and therefore can be used in green spaces planning to specify and quantify the suitable sites in line with the other approaches.

Conclusions

In this study, GIS-based multi-criteria analysis has been used to support the site selection process for the development of urban green spaces. The study results are very significant in evaluating the feasibility of the use of GIS-based multi-criteria analysis for the development of urban green space. Since, by using appropriate analytical methods, the evaluation of urban green space is necessary to recognize their potential and to better select the most suitable land uses to improve their integrity and maintain the benefits obtained from them.

In the present study, the sub-criteria for site suitability for urban green spaces in order of importance were area with high population density (22 %), Proximity to settlement area (21 %), Slop (13 %), Proximity to the road (10 %), elevation (5.9 %), vegetation cover (4.8 %), Proximity to water sources, visibility and existing land (3.2 %) and flood prone area (4 %). The GIS-based multi-criteria analysis performed in this study found that, in the current situation, the larger land mass (47 %) of the town is suitable for developing urban green spaces. The town, therefore, has great potential to develop adequate urban green spaces.

GIS technologies can play a crucial role in urban green space planning, as shown in this study, and AHP has been shown to be a flexible and realistic tool for selecting areas for urban green spaces in the study area. This can be attributed to participation of experts in the determination of the criteria and sub criteria using AHP. Furthermore, GIS may be used to support spatial decision-making, as it has excellent spatial problem solving capabilities. Therefore, this study can provide a framework for the planning process using GIS and AHP for Ethiopian County planning and the results can be useful in the planning of urban green space and future land use planning in study town.

Finally, future research should focus on assessing the suitable site selection for each urban green spaces component such as park, playground, sport field, and the like, independently. In this study, the same criteria and sub criteria were considered to select suitable site for all components of urban green space. Therefore, considering criteria and sub criteria for each component separately are necessary in order to provide a complete understanding of urban green space suitability analysis.

Availability of data and materials

All data generated or analysed during this study are included in this published article.

References

Acknowledgements

The author wishes to thank Sululta town municipality experts who participated in ranking the value of criterion map for pairwise matrix.