Planning Assessment
Overview: Framework for Quantitative Assessment of Urban-Blue-and-Green-Spaces in a High-density Megacity
2022 Volume 10 Issue 3 Pages 280-301
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2022 Volume 10 Issue 3 Pages 280-301
Urban-blue-and-green-spaces (UBGS) comprising waterbodies and green spaces are intrinsic to the urban environment due to their immense ecological, social, economic, and health benefits. Owing to high population densities, megacities in countries with emerging economies are losing their natural areas, adversely affecting the urban environment. This article studies the current built-open space dynamics and proposes a conceptual framework for the quantitative assessment of UBGS in the Indian megacity of Kolkata at the smallest administrative unit called wards. Results show that the available UBGS is 11.51% of the total area and 5.08 sq.m per inhabitant, both of which are far below the national and international urban planning guidelines. The wards are appraised for two indices, UBGS Distribution Index and UBGS Availability Index, based on spatio-physical distribution and per inhabitant availability, respectively, comparing them with the Indian urban planning standards. The indices represent the actual shortfall of UBGS in each ward in terms of minimum requirements as per national standards. The present unequal distribution of UBGS in the city is a matter of social and environmental justice that needs to be addressed. The indices show a correlation of 0.6688. This framework can help decision-makers protect, preserve, and promote the city's UBGS by adopting a bottom-up approach to solve local issues and providing safe and socially inclusive public spaces for all sections of society.
'Urban-blue-and-green-spaces' (UBGS) are fundamentally the areas with 'natural surfaces' or 'natural settings' (WHO Regional Office for Europe, 2016). Still, they may also include the 'blue and green' artificially landscaped components. 'Urban Blue Spaces' comprises saltwater and freshwater wetlands (Ramsar/Convention/Secretariat, 2016), while 'Urban Green Spaces' encompass all visually and physically accessible open areas with considerable vegetation cover. In this study, the term 'UBGS' includes both the 'blue' and 'green' components of a city's landscape, such as the wetlands (urban lakes, local water bodies), natural and semi-natural areas (urban agricultural lands, wastelands), recreational green spaces (urban parks, local parks, formal gardens, sports areas, and tot lots), institutional grounds, cemeteries, and linear green spaces (rivers and canal banks).
Urban greenery and wetlands are considered the 'harbinger of sustainability' (Bardhan, Debnath et al., 2016). Significant benefits are environmental, health, social capital and cohesion, and recreation (Kim, Rupprecht et al., 2020; Wendel, Zarger et al., 2012). Environmental benefits include the provision of essential ecosystem services, pollution attenuation, noise reduction, biodiversity conservation, urban heat island mitigation, water storage, flood control, agriculture, aquaculture (Bowler, Buyung-Ali et al., 2010; Ghofrani, Sposito et al., 2017; Millennium/Ecosystem/Assessment, 2005; Spronken-Smith and Oke, 1998). Physical and mental health benefits include reduced rates of depression, cardiovascular morbidity, mortality, obesity, and diabetes (Engemann, Pedersen et al., 2019; Thompson, Roe et al., 2012; Tomita, Vandormael et al., 2017; Ulrich, Simons et al., 1991; WHO Regional Office for Europe, 2016). Social capital and cohesion are improved due to increased social interactions, thus supporting a sense of community (Kim, Rupprecht et al., 2020; Martin, Warren et al., 2004). Economic benefits include employment and revenue generation, and property prices (Arvanitidis, Lalenis et al., 2009).
Currently, the effects of the changing climate, significantly increasing temperatures, frequent floods, droughts, heatwaves, and cyclones, have become significant challenges for cities (Benedict and McMahon, 2002; Cohen-Shacham, Walters et al., 2016; Kim, Rupprecht et al., 2020). A generous share of UBGS within the built environment is the ecological backbone for the city's environmental, economic, and social sustainability and a tool for safeguarding a city against the natural calamities by creating resilience. Access to and availability of green spaces are related to social and environmental justice (Kabisch and Bosch, 2017; Ngom, Gosselin et al., 2016; Wolch, Byrne et al., 2014). The UN Sustainable Development Goal 11.7 aims to provide universal access to safe, inclusive, accessible, green and public spaces for all sections of the society by 2030. Developing an easily computable and cost-effective method to assess UBGS and producing locally relevant, comparable data at the smallest administrative level is essential. It enables planners and decision-makers to evaluate the need for improvement, identify the specific areas which need immediate interventions, and the aspects to consider when planning for UBGS interventions (WHO Regional Office for Europe, 2016).
The present study is based on the Indian city of Kolkata, the state-capital of West Bengal (Figure 1). The city is administered by the Kolkata Municipal Corporation (KMC) and is situated in the centre of the Kolkata Metropolitan Area (KMA), the larger urban agglomeration of the city that grew up surrounding the core city. This study covers 206.08 sq. km of the KMC area, consisting of 144 wards (administrative units) grouped into 16 boroughs (administrative blocks).
Kolkata is a growing megacity with mounting pressures on its existing natural resources due to its ever-increasing population, urban sprawl, inadequate infrastructure, and poor governance (Mukherjee, Bebermeier et al., 2018; Ramachandra, Aithal et al., 2014). The urbanisation pattern of Kolkata is an outcome of several natural and socio-economic factors, policies and practices, legal and regulatory frameworks, governance systems, financial tools, and informal methods (Haque, Mehta et al., 2019). With the sudden growth of the urban population, demand for housing and commercial spaces has created horizontal and vertical pressure on land resources. Distortions in policies and regulations, inefficient administration, a scarcity of reliable and complete data, and lack of funds and infrastructure are formidable barriers to adopting innovative methods in the sustainability pathways.
A detailed review of existing literature (elaborated in Section 2.1) reveals that most focus on the city-level distribution of natural areas within the urban or peri-urban areas. Spatio-temporal maps show the non-uniform distribution of UBGS within the metropolitan area with apparent absence in significant parts of the city and critically low in most other regions. There is an imminent need to develop, provide, and maintain a minimum proportion and equitable share of UBGS in each neighbourhood to maintain healthy and sustainable living conditions. The authors noted that a locally relevant database on the availability or shortage of open areas might guide decision-makers more effectively in addressing the micro-level issues. This study aims to ward-wise comprehensive analysis and indexing of UBGS. In the Indian municipal system, wards are the smallest administrative units under elected ward councillors. The councillors have the freedom and responsibilities to upgrade civic amenities, set goals, and formulate local-level strategies. A bottom-up approach to improving the local environment will enhance the city's overall environment. This study suggests a systematic procedure where the wards are assessed and indexed for availability or shortage of UBGS for decision-makers to formulate ward-specific strategies to achieve an ecologically sustainable urban neighbourhood with optimal grey-green proportions and equitable share of UBGS per inhabitant.
Kolkata was established as a port city by the British East India Company on the eastern bank of the river Bhagirathi-Hooghly. Located within the lower Gangetic deltaic floodplains, the city prospers with rich biodiversity and natural ecosystems such as the East Kolkata Wetlands (a Ramsar site of international importance), two rivers, and an efficient canal system. Being the capital of British India until 1911, Kolkata expanded swiftly. Since there was no possibility of expansion towards the west due to the presence of the river, Kolkata progressively expanded towards the east, reclaiming the invaluable wetlands. The city's growth accelerated after India's independence and subsequent partition with Pakistan in 1947, followed by the Bangladesh war of liberation in 1971. To accommodate a massive population influx from neighbouring states and countries, Kolkata underwent unexpected densification, with insufficient facilities and infrastructure, resulting in environmental degradation and a lack of open spaces (Bhatta, 2009).
Recently, with a population density of around 24,760 per sq. km(Kolkata/Municipal/Corporation/(Official/Website), 2019), the natural areas in and around the city are experiencing severe human intrusions (Ramachandra, Aithal et al., 2014). Kolkata suffers from urban environmental challenges of loss of biodiversity and natural habitat, high pollution, land-use changes, over-exploitation of natural systems, and loss of livelihoods. A decadal study of urban growth by Mukherjee, Bebermeier et al. (2018) displays the severe loss of valuable natural areas over the past decades. The natural en¬vironment is relegated to inconspicuous fragments of the original ecosystems within the dense urban fabric. Rapid encroachment of vacant lands and water bodies in the eastern periphery had drastic influences on the land-use pattern and resource management. In 2015, collaborative research (Figure 2) by various researchers and organisations stated that the open areas in the city dropped from 25% of total areas in 1990 to a meagre 10% by 2015, while residential and commercial land covered 79% of the total area (Reporter, 2017). Recorded forest cover is nil (Govindarajulu, 2014), with only 6% road infrastructure (Bardhan, Debnath et al., 2016; Census/of/India, 2016).
The study aims to understand the built-open relationship of Kolkata city and gain a general overview of the cityscape, emphasising the assessment of UBGS at the local level. The entire suite of the methodology is presented in Figure 3. The research objectives are as follows:
However, the study indicates a quantitative distribution, availability, and shortage of UBGS; it does not show their quality, ease of accessibility, safety, functionality, or ecological characteristics. Besides, avenue trees, private courtyards, incidental landscaped areas, roof gardens, vertical gardens, and rainwater harvesting systems are not considered, although they provide vital ecosystem services and add to the green cover of a city.
Stage 1 gives a complete term overview of the UBGS scenario in Kolkata. The authors reviewed and analysed the accessible data drawn from various archives, maps, and technical reports. Data on the area and population of individual wards are sourced from the KMC Official Website. Data on parks and water bodies are acquired from Kolkata City Park and Project Management Unit, KMC. Web-based services such as Cadmapper, Google Earth, and Bhuvan (the national Geoportal) were used to acquire geospatial data for analysis. AutoCAD 2014, Adobe Photoshop CS6, and MS Office were used for precise mapping and calculation of existing UBGS. The map presented in Figure 4 is the outcome of the meticulous plotting of the existing UBGS in Kolkata.
Further, the availability and shortage of UBGS in Kolkata are compared to one national and three global urban planning regulatory standards. The URDPFI (Urban Development Plans Formulations and Implementation of India) guidelines, published by The Ministry of Housing and Urban Affairs, Govt. of India, is the Indian standard for urban planning, initially formulated in 1996 and revised in 2014. It provides a framework for planning and implementation in an urban region intending to provide an adequate and equitable share of physical and social infrastructure for all sections of the society. All urban planning and development in India must abide by the standards set by URDPFI. Additionally, three internationally acclaimed standards for sustainable cities and environmentally responsive neighbourhoods were studied and compared to estimate the real-life scenario in Kolkata, namely World Health Organisation (WHO Regional Office for Europe), United Nations Human Settlements Programme (UN Habitat, 2018), and Leadership in Energy and Environmental Design – Neighbourhood Development (LEED-ND) (as shown in (Figure 5). The minimum proportion of UBGS, as recommended by the significant regulatory bodies, is as follows:
The graphs in Figure 6 compare Kolkata with some important cities in India and worldwide in terms of spatio-physical distribution and per inhabitant availability of UBGS. This comparison gives an idea of the actual situation of the built-open space relationship in Kolkata compared to other cities of equivalent stature. The rationale behind the selection of cities is their importance as country capital or state capitals. Being the administrative seats, most of these cities have higher population densities than other cities in the same country or province.
Stage 2 (Ward-level assessment of UBGS)This stage provides a specific inventory of UBGS in each ward. A detailed ward-level assessment is done considering the area, population, and available amount of UBGS in each ward. The authors introduced two parameters based on the spatio-physical and human perspectives of UBGS. The former indicates the environmental status of the individual wards considering the variables of ward area and available UBGS. The latter, i.e. the human perspective, shows the same for health and other benefits considering the variables of ward-wise population and availability of UBGS. The analysis mentioned above is done to understand the spatial distribution of UBGS and its availability to the residents, denoting the shortfall in each ward. Two separate maps are presented in Figure 7 with tonal colour variation representing the ward-wise distribution and visually demarcating the wards with critically low to high proportions of UBGS.
This stage also provides a deeper understanding of the shortfall between the ideal and the actual in relative terms. A composite bar diagram in Figure 8 shows the real shortage and availability of UBGS represented ward-wise and under each borough. The theoretical model establishes the performance of the individual wards in terms of available UBGS compared to the standards mentioned in URDPFI Guidelines. Average values of 15% of the area and 11 sq. m of UBGS per inhabitant are considered for the calculations. Based on this guideline, two indices are developed by the authors:
Stage 3 attempts to understand the relationship between ward-wise area, population, and available UBGS. A Scatter-plot diagram in Figure 9 shows the correlation between the two indices representing the relationship between the respective area, population density, densification pattern, and available UBGS in each ward.
Stage 4 (Strategy recommendations - Application of the Indices)Stage 4 provides an application of the assessment framework by recommending strategies that may quantitatively and qualitatively enhance the UBGS based on the results of the indices. Wards are classified into three categories depending on the availability of UBGS, followed by specific strategy recommendations for each type.
Figure 4 presents the actual distribution of UBGS in Kolkata as of 2020. As the early urban agglomeration in eastern India, Kolkata exhibits uneven urban growth and population density. The map shows that the UBGS in the KMC area is not uniformly distributed. The entire north and most of central Kolkata are dominated by residential and commercial buildings with a higher population density than the remaining parts of the city. This reason stems from the fact that these are the oldest parts of Kolkata and, consequently, have evolved organically since the colonial era. The only substantial green space around central Kolkata is the Maidan, which the British planners envisioned as an urban park.
In contrast, the city's southern, eastern, and western peripheries have substantially more UBGS which are remnants of the wetlands and peri-urban agricultural lands. These are relatively the newer parts of the city, which were annexed from adjacent non-built-up areas. Consequently, these areas were designed following efficient byelaws for mandatory open spaces. Uneven distribution of UBGS is also a concern of social and environmental injustice. Each citizen is entitled to a minimum share of UBGS irrespective of age, social or financial status.
The inset in Figure 4 indicates that the total amount of UBGS in Kolkata is approximately 22.85 sq. km (11.51% of the total area). It consists of 15.75 sq. km (7.93% of total area) of green areas and 7.10 sq. km (3.58% of total area) of water bodies and wetlands [Refer to Table I in Supplementary]. The individual share of UBGS is 5.08 sq. m/person, which is far below the minimum requirement set by national and global standards, as shown in Figure 5. Similarly, the graphs in Figure 6 show that Kolkata fares better than some cities worldwide in the total provision of UBGS due to vast expanses ofwetlands on the eastern fringes. However, due to high population density, individual share UBGS is critically low compared to the same cities and the standard mandates.
(Refer to Tables II and III for the sources of data)
(Refer to Table I for the source of data and calculation procedure).
Maps in Figure 7 represent the availability of UBGS in terms of the two parameters introduced by the authors. The spatio-physical and human perspective parameters respectively signified the availability of UBGS in percentage and per inhabitant. Wards are classified into five categories for each parameter, represented by varying shades of colour, the darker shades indicating higher proportions of UBGS than the lighter shades. The wards have a proportion of UBGS lower than 15% or availability less than 11 sq.m per inhabitant can be considered critical as per URDPFI guidelines. The critical wards are mostly located in the north, west, and central parts of the city. The southern and eastern parts are above safe limits due to passive green areas like wetlands and agricultural lands.
Figure 8 provides a deeper understanding of the shortfall between the ideal and the actual in terms of the two indices developed by the authors, namely the UBGS Distribution Index (I1) and UBGS Availability Index (I2), which are expressed as ratios in comparison to URDPFI guidelines.
The ideal required ratio in either index is 1; these are the cases where the wards meet the standard UBGS requirement of 15% of the total area, or 11 sq. m per inhabitant. Based on the actual performance of the wards in terms of the indices, they are classified into four grades representing an increasing magnitude of UBGS availability, starting from critically low (index value less than 0.5), low (0.5 to 1), average (1 to 2), and high (above 2). These indices signify the actual shortage in each ward and the level of attention needed to protect, restore, and promote existing UBGS or create new ones by developing specific mandates, guidelines, and conservation measures. By default, this gives an idea of the landscape intervention range from quantity (creation of new green areas) to quality (conservation of the already existing ones) and from the smallest built unit to vast natural landscape areas. It also helps identify potential and envisaging interventions required to achieve the broad vision of making a greener, sustainable, and resilient Kolkata. The results are supported by a graph where the wards can be identified as the parameters of 'openness,' i.e., the defined indices.
(Refer to Table I for the source of data and calculation procedure)
This Scatter plot diagram in Figure 9 correlates the two indices representing the relationship between the respective area, population density, densification pattern, and available UBGS in each ward. The red markers show the I1 vs I2 data set. The black dashed line represents a straight line with a slope identical to the linear correlation coefficient R=0.6688, indicating that the indices are moderately correlated. The solid blue line represents a linear fit of the data set with a coefficient of determination (R2) value of 0.4473. This further substantiates that the congested wards having high population density have higher proportions of built-up areas with minimum or no available UBGS leading to unhealthy environmental conditions. Exceptions are seen in the wards, which had been recently annexed from the adjacent peri-urban areas where there are vast expanses of wetlands or agricultural lands with low population density.
Along with preparing a local-level database for the city, this paper aims to provide a suggestive application of the study. Table 1 shows some recommendations that may quantitatively and qualitatively enhance the UBGS based on the results of the indices. Specific strategies are suggested for each category, classified based on the above studies. These locally applicable strategies aim to conserve the existing UBGS, increase the UBGS cover in the critical wards, and provide access to an equitable share of UBGS for all sections of society. Some of the notable publications referred by the authors are Haaland and van Den Bosch (2015); Jim (2004, 2013).
| Categorisation of wards | Principle | Area of application | Strategies recommended |
| Critically Low (Index Value: 0 to 0.5) | Integration of green infrastructure into grey infrastructure | Existing buildings | Green roofs and green walls |
| Developing buildings | Making strict norms for mandatory open spaces and offering incentives for tax reduction or additional floor area benefits to implement any façade-based and ground-based green infrastructure and rainwater harvesting options. | ||
| Joint use of institutional amenities – shared spaces | Gardens or playgrounds in educational institutions can be shared with the local people after regular academic hours | ||
| Streetscaping | Roadside plantation, permeable paving material, vegetated swales | ||
|
Low (Index Value: 0.5 to 1) |
Integration of green-grey infrastructure | Interstitial vacant spaces | Organised planting and management of vacant lands, parking areas, rail tracks, and corridors between buildings |
| Neighbourhood parks, playgrounds, gardens, and cemeteries | Proper maintenance of these parks and converting them into multi-functional areas to cater to all sections of people | ||
| Local waterbodies | Proper maintenance of local water bodies to raise their cultural and ecological value | ||
| Gardens around the historical or important building | A revival of these gardens or making them open to public | ||
|
Average to High (Index Value: Above 1) |
Preservation of already existing green infrastructure | East Kolkata Wetlands, urban parks, and lakefronts | Preserving the existing natural assets and protecting the eco-sensitive zones |
| Riverfronts and canal-banks | Creating a continuous "ecological corridor" to bring nature into the congested wards |
Thus, in the wards with minimal or no UBGS cover, there is necessary to continually look for green spaces or plantable spaces in the building premises, housing complexes or create greenery in the form of roof gardens or green walls to increase the green cover. However, in the wards with ample natural components such as urban parks, wetlands, and agricultural lands, the focus is more on their preservation and qualitative enhancement than on creating new UBGS. A planned increase in the UBGS cover can inevitably improve a city's environmental conditions, such as air purification, groundwater recharge, microclimate control, and habitat for urban biodiversity.
This study is a quantitative assessment of UBGS distribution in Kolkata; it does not investigate the quality of the open spaces or their ecological aspects. However, along with the quantitative sides, qualitative factors such as species richness, water quality, and canopy cover need to be monitored and enhanced for a more sustainable urban ecology. The pre-urbanisation character and native trees need to be replicated and the contaminated, degraded canals and waterbodies restored, and vast paved areas replaced with vegetation or permeable surfaces. Further, using the waterways as a link to connect the fragmented remnants of urban nature will be another step forward in preserving the rich natural resources the city possessed before urbanisation happened.
It can be concluded from the study that Kolkata suffers from uneven distribution of UBGS due to various factors, which may lead to serious environmental hazards and poor living conditions in significant parts of the city. Kolkata's present situation demands a restructuring of the existing built-open space strategies and regulatory norms to achieve harmony between distributions of UBGS in the city. The city's spatial policy aims and directions should emphasise maintaining a reasonable proportion of natural and built-up areas. Uneven distribution and unequal access to UBGS are an issue of environmental justice (Kabisch and Bosch, 2017). To ensure that all inhabitants have a minimum amount of UBGS within their visual and accessible limits and therefore benefit from the ecosystem services, health and recreational aspects provided by them, they must maintain the threshold value of UBGS.
As mentioned in Section 2.1, Kolkata has a legacy of rich natural heritage consisting of several ecologically rich resources. Unfortunately, the city's growth was not always on a sustainable trajectory due to various factors. As a result, Kolkata faces an acute shortage and unequal distribution of UBGS concerning social and environmental injustice that needs to be overcome. The benefits of UBGS are also not yet fully recognised. The short-term economic benefits of converting wetlands into residential or commercial land-use are more lucrative than the long-term benefits of maintaining those. The parameter-based framework suggested in this paper includes a methodology to procure accurate data on UBGS at the local level. Analysing current data can provide a valuable model for adopting locally derived, locally applicable strategies and efficient resource allocation to achieve an ecologically sustainable urban neighbourhood with optimal grey-green dynamics and an equitable share of UBGS per inhabitant. This analytical tool can be applied to any city, particularly in developing countries where urban sprawl and rapid and unplanned urbanisation are the primary concerns. Assessment and indexing of UBGS at the smallest administrative level enable policymakers to address local-level issues and provide local-level solutions. Reinforcing adequate green coverage from the smallest household scale to the largest urban scale will check environmental degradation and help meet the UN Sustainable Development Goal of providing universal access to safe, inclusive, and accessible public green spaces for all sections of the society.
All authors have equal contributions. All authors have read and agreed to the published version of the manuscript.
The authors declare that they have no conflicts of interest regarding the publication of the paper.
The study uses secondary data from various sources for comparative analysis. Authors duly acknowledged the various parties and portals for using the data.
| City | Geographical Area (sq.km.) | Population (in million) | Availability of UGS/inhabitant (sq.m.; 2018) | Distribution of UGS (%; 2017) |
|---|---|---|---|---|
| Delhi | 1484 | 28.5 | 5.5 | 10.56% |
| Bengaluru | 4381 | 13.9 | 2.01 | 8.40% |
| Mumbai | 603 | 23.5 | 2.01 | 7.83% |
| Hyderabad | 650 | 11.57 | 0.5 | 0.89% |
| Ahmedabad | 464 | 8.41 | 3.9 | 7.07% |
| Chennai | 1189 | 9.88 | 1.03 | 0.86% |
| Surat | 326 | 6.55 | 2.7 | 5.42% |
| Jaipur | 467 | 3.71 | 20 | 15.89% |
| Gandhinagar | 649 | 6.33 | 147.6 | 143.96% |
| Chandigarh | 114 | 1.05 | 54.45 | 50.15% |
Source: Ramaiah and Avtar (2019)
Source: http://www.worldcitiescultureforum.com/data/of-public-green-space-parks-and-gardens
