Equitable urban green space planning for sustainable cities: a GIS-based analysis of spatial disparities and functional strategies

Validity and reliability of the thematic mapping of UGS

As a result of our thematic map accuracy assessment, Table 4 presents a confusion matrix and the Kappa coefficient based on the raster map’s predictions (EqS. 1–4). In each row, the predicted values are represented by the raster map. In contrast, in each column, the reference data is presented. A diagonal entry in the matrix indicates the predicted value matches the reference value, while an off-diagonal entry indicates a mismatch. The recreational typology land use class “Parks and Gardens” is 97% accurate, with 56 correct predictions out of 58, whereas the “Playgrounds” class shows 48 correct predictions out of 50, giving a 96% accurate score. As a result of GPS points obtained through an on-site visit using a boat, the “Lakes” class obtained 100% accuracy, with all four instances predicted correctly.

In contrast, the “Waterway Green Spaces” and “Forests” classes are 96% and 94% accurate. Users’ accuracy for the “Institutions and Campuses” class is 93%, while the “Urban Green Belts” class is 98%. The producer’s accuracies also indicate a high level of reliability across most classes, with the “Lakes” class achieving 100% accuracy. Based on the sample size of 301 points, the thematic map was observed to be 95.68% accurate overall (Table 4). It indicates a very high level of agreement between predicted classifications and reference data, as measured by the Kappa coefficient, 94.61%. In this study, the thematic map accurately represents the spatial distribution of land cover classes and is reliable and valid. In addition to its high Kappa coefficient and overall accuracy, the classification model is effective at distinguishing classes, making it a useful tool for spatial analysis.

Thematic categories and spatial analysis of UGS

In-depth thematic mapping of Islamabad’s UGS reveals its spatial distribution and classification. UGS categories are visualized in a comprehensive approach on the generated successive maps in Fig. 6a, b, c, d. Recreational UGS includes designated parks, gardens, playgrounds, lakes, waterways, green spaces, and forests. It enhances urban aesthetics and offers valuable recreational opportunities. Institutional UGS on government and educational campuses supports biodiversity and ecology. Providing recreation opportunities and improving air quality mitigates urban sprawl. As indicated by the spatial distribution, there are significant designated parks and gardens (12.45 km²), playgrounds (3.58 km²), lakes (6.26 km²), green spaces along waterways (4.99 km²), forests (2.38 km²), institutional campuses (17.05 km²), and green belts (9.82 km²). UGS is crucial in maintaining a sustainable urban environment and providing recreation, environmental, and aesthetic benefits for Islamabad residents through meticulous mapping and categorization. Besides improving urban life quality, this detailed analysis highlights the need to maintain and expand green spaces.

Thematic mapping illustrating the successive layers of public urban green spaces (UGS): (a) Designated parks and gardens, including playgrounds and lakes; (b) forest buffer zones surrounding urban settlements specifically allocated as buffer zones; (c) institutional green spaces and water corridors following natural drainage lines; (d) green belts specifically allocated between planned sectors.

Recreational UGS—lakes

The lakes in Islamabad serve as significant recreational urban green spaces, providing ecological and social benefits. Prominent lakes such as Rawal Lake in the Margalla Hills National Park are developed with attached parks and gardens to fulfill recreational needs (Fig. 6a). These areas cater to a diverse population, offering activities such as boating, picnicking, and bird watching, thus enhancing the recreational landscape of the city. However, accessibility issues and maintenance challenges can limit their optimal use.

One of the notable water bodies in Islamabad is the Korang River, which originates from the Murree Hills and flows through Islamabad into the Rawal Lake. The Korang River plays a crucial role in the region’s hydrology, supplying water to Rawal Lake and providing drinking water to the residents of the twin cities (Rawalpindi and Islamabad). Despite its importance, the Korang River faces significant pollution challenges. Urban encroachments, industrial discharge, and untreated sewage have severely impacted the river’s water quality, posing environmental and health risks. Efforts to mitigate pollution include regulatory measures and public awareness campaigns, but enforcement remains inconsistent.

Other lakes and water bodies within the city also face underutilization due to urban congestion and environmental degradation. Despite efforts by local authorities to revitalize these water bodies, such as creating promenades and leisure areas, the provisions often remain underutilized due to poor maintenance and limited public engagement. Additionally, some lakes suffer from pollution and are used as dumping sites for sewage and garbage, detracting from their ecological and recreational potential.

Efforts to enhance the appeal and usability of Islamabad’s lakes include the development of better access points, regular maintenance, and public awareness campaigns to promote environmental stewardship. The potential of these lakes to serve as key urban green spaces can be fully realized through integrated management approaches that address ecological health and recreational infrastructure. The transformation of these lakes into vibrant public spaces would contribute significantly to the city’s sustainability and the well-being of its residents.

Recreational UGS—urban forest

Maintaining urban biodiversity and ecological balance in areas surrounding developed regions is essential, particularly in urbanized areas. These densely vegetated areas were purposely left undeveloped during city planning as buffer zones (Fig. 6b). Unlike the designated green belts and waterways green spaces, these regions remain pristine, undeveloped land that significantly contributes to the health and well-being of the city. Planning documents from the CDA reveal the strategic importance of these buffer zones in mitigating urban sprawl and preserving natural landscapes. During our field survey, we identified these densely vegetated areas in H-12, H-10, and the north-east side of the diplomatic enclave and classified them as urban forests. The vegetation in these areas is similar to that found in waterway green spaces and urban green belts, including native plants that thrive in undisturbed natural environments.

Institutional UGS—government and private institution

In an urban matrix, allocated space for institutions and a proportion of the green areas serve as critical ecological refuges. In addition to purifying air, they sequester carbon and regulate temperature. Additionally, green areas on educational campuses serve as living laboratories for environmental education. Thus, urban biodiversity is enhanced. These green spaces facilitate a deeper connection with nature and provide students and faculty with a natural setting for learning and relaxation. The aesthetic appeal of institutional buildings is also enhanced by maintaining grey and green structures (Fig. 6c). Ornamental and native plants improve urban sustainability and livability by supporting local biodiversity and mitigating the urban heat island effect. UGS management is essential to maximizing their ecological benefits.

Substantial areas have been allocated to public and private universities and institutions (Fig. 8), reflecting the commitment to education and research. The H-10 sector, designated for the International Islamic University, Islamabad (IIUI), spans a significant expanse and includes extensive green areas contributing to urban biodiversity and ecological balance. Similarly, the most sustainable campus in Pakistan and the world’s top-ranked (101–200 in Times Higher Education impact ranking), the National University of Sciences and Technology (NUST), occupies a large campus with well-maintained lawns and diverse plantings that support a variety of fauna. Similarly, Quaid-i-Azam University (QAU), with its sprawling campus set against the backdrop of the Margalla Hills, serves as a crucial ecological and educational hub. The Allama Iqbal Open University (AIOU) also covers a vast area, incorporating green spaces that enhance the urban environment. Beyond these major universities, numerous schools, colleges, and government departments are strategically situated throughout Islamabad, each contributing to the city’s green infrastructure (17.05 km²). These educational and governmental institutions foster learning and research and play a pivotal role in maintaining the city’s ecological resilience and sustainability by integrating substantial green spaces within their campuses.

Recreational UGS—designated parks and gardens

The provision and maintenance of parks and gardens within Islamabad’s planned residential sectors of Zone I are managed by the Capital Development Authority (CDA). As depicted in the figure, the parks and gardens vary significantly in size and layout across different sectors (Fig. 6a and Fig. 7a). These green spaces typically include amenities such as walking tracks, children’s play sections, gym areas, open lawns, and seating benches, with the level of maintenance differing from one sector to another. The frequency distribution graph based on the area (km²) indicates that smaller parks are more prevalent, predominantly located in residential neighborhoods (Fig. 6a). In contrast, larger parks, though fewer in number, are strategically placed to serve broader community needs across different sectors (Fig. 7 a. The provision of outdoor gym equipment is a recent addition and is widely used; however, in some places, the position is random. As very few parks have more area (Fig. 6a), such as F-9 Park, Lake View Park, Japanese Children Park, Rose and Jasmine Garden, and Kachnar Park, are added with more facilities.

The qualitative survey reveals that park accessibility in Islamabad varies based on gender, age group, designated hours, and proximity to residential areas, as reported by community members and stakeholders. Small parks with limited facilities within residential localities were found to be generally accessible to the public and heavily influenced by community involvement in maintaining and providing facilities. The CDA, cleanliness, and maintenance are only subject to the participation of locals; no regular services of such activities are provided; in many sectors (I and G series), nominated groups of residents manage these parks, address facility issues, and oversee maintenance with the help of the CDA. Conversely, large parks are directly managed by the CDA and maintained by designated staff. Additionally, some parks are adopted by third parties for development and maintenance, ensuring higher standards of care and facility management. Most large Parks charge nominal fees for the entrance and parking areas and the recreational facilities owned by the private sector.

A detailed qualitative survey revealed that parks and gardens have significantly enhanced residents’ quality of life, highlighting their role in social interaction, mental well-being, and recreation of Islamabad by providing ecological services. Undoubtedly, parks and gardens have played a pivotal role in this improvement. Indigenous plants such as Neem (Azadirachta indica), Amaltas (Cassia fistula), and Chir pines (Pinus roxburghii) are found very common, along with seasonal shrubs to enhance recreation like Jasmine (Jasminum officinale) and Hibiscus (Hibiscus rosa-sinensis), which contribute to carbon dioxide sequestration (Supplementary Table I). These parks and gardens also maintain ecological balance by providing bird and insect habitats while offering water management services that mitigate climate-related impacts. Strategically planned, most parks and gardens effectively reduce surface runoff, recharge groundwater, and prevent soil erosion. Moreover, parks regulate urban microclimates, lowering ambient temperatures and creating comfortable outdoor spaces, counteracting the urban heat island effect. Beyond their environmental benefits, parks positively influence mental and physical health. By promoting physical activity, reducing stress, and offering natural recreational opportunities, green spaces contribute to climate adaptation.

Recreational UGS—waterways green spaces

A vital component of Islamabad’s green infrastructure is left along natural drainage lines, such as Nullah Lai. The plant communities in these areas are distinct due to soil properties and human activities and feature a variety of native and invasive species³³. Higher moisture content areas tend to support native species like Populus euphratica and herbaceous plants, while disturbed sites tend to support invasive species like Broussonetia papyrifera (Supplementary Table 2). These green spaces provide wildlife habitat in urban ecosystems, increasing ecological resilience. Our close observations indicate that these areas are often underutilized due to poor maintenance and public awareness despite their environmental importance. It is essential to preserve native species, control invasive species like Broussonetia papyrifera, and monitor soil properties. Green spaces can be fully realized if they are accessible and sustainable. There are distinct distributions of small and large patches, covering an area of 4.99 km²; the majority are relatively small (0.1 km²) (Fig. 7c). Despite their small size, these patches contribute significantly to urban biodiversity, flood mitigation, and other ecosystem services. Despite their smaller numbers, larger patches play a significant role in urban ecological resilience and provide greater recreational opportunities and habitat. Islamabad’s environmental health and sustainability depend on the conservation and enhancement of waterway green spaces, both small and large.

Area-wise frequency distribution of (a) parks, (b) playgrounds, and (c) waterways green spaces in Islamabad.

Recreational UGS—playground

The study revealed a diverse range of recreational UGS, primarily focused on sports facilities, across selected sectors in Islamabad (Fig. 7b). While many sectors provided football and cricket grounds, contributing to urban heat mitigation and ecosystem services, the distribution of other sports facilities was uneven (Fig. 8). Tennis and basketball courts were present in some sectors, promoting physical activity and social cohesion. Specialized facilities like karting, paintballing, and skating were limited and often required extensive travel. A significant gap was identified in providing gender-specific playgrounds and facilities, with most catering to young males. Additionally, many public spaces were overcrowded due to a lack of designated sports areas, and existing facilities often suffered from poor maintenance, inadequate safety measures, and limited vegetation. The study also highlighted the challenges of managing and maintaining recreational UGS, with varying public and private involvement levels.

Area-wise frequency distribution of institutional green spaces across the selected sectors of Islamabad.

Green belts— urban green belts

The green belts in Islamabad were strategically included in the Master Plan to act as buffers between different urban sectors, preserving aesthetic appeal and maintaining ecological balance (Fig. 6d). Field observations indicate that, despite their ecological significance, these green belts face challenges from infrastructure development and informal settlements. Encroachment from road construction and other development projects has reduced their size and functionality. Regular maintenance, preservation of native species, control of invasive species, and monitoring of soil properties are essential to sustain the ecological functions of these green belts³³. Their strategic placement and diverse vegetation make them indispensable components of the city’s green infrastructure, significantly contributing to the environmental health and sustainability of Islamabad. The concept of using green belts to prevent the merging of rural and urban areas dates back to World War II³⁴. The reasons for implementing green belts around cities varied: in England, they were used to stop urban expansion, while in Jerusalem, they served political purposes³⁵. In Islamabad, green belts serve a unique purpose. According to the Master Plan of Islamabad, green belts were incorporated along every service road and highway. These green belts were intended for future road expansions and to act as barriers, separating residential areas from the roads. Thematic observations reveal that these green belts are underutilized, highlighting the need for better management and utilization strategies to maximize their ecological and social benefits.

The graph illustrates the distribution of green belt areas in Islamabad, highlighting their frequency of occurrence across different size categories. This study identifies the area of current green belts (9.82 km²) (Fig. 9). Most green belts are relatively small, with the highest frequency observed in areas less than 0.1 km².

Distribution of Green Belt Areas highlighting the prevalence of small green spaces within the urban landscape.

Thematic quantification of UGS

Distribution and sizes of different Urban Green Space (UGS) types were qualified based on thematic observation and mapping (Fig. 10). The Urban Green Belts and Institutional UGS categories dominate, with total areas of 19.64 km² and 17.05 km², respectively. Recreational Parks and Gardens also hold significant space at 12.45 km². The mean area values indicate the average size of individual spaces, while the maximum values show the largest spaces within each type. Figure 10 complements this by showing the proportional distribution of each UGS type, with urban green belts (UBG) and institutional green spaces (IGS) making up over half of the total UGS area, highlighting their importance in urban planning and sustainability. This combined analysis underscores the focus on extensive green belts and institutional spaces while noting the substantial role of recreational parks.

Analysis of UGS types: total area, mean, maximum values, and proportional distribution.