Approaching URBAN SUSTAINABILITY USING DENSITY ASPECT OF COMPACT CITY PLANNING

Approaching URBAN SUSTAINABILITY USING DENSITY ASPECT OF COMPACT CITY PLANNING

Dr. Rajashree Kotharkar, Ashish Vyas

Department of Architecture and Planning, Visvesvaraya National Institute of Technology

Nagpur, India

Abstract

Exploitation of land and other resources is critical issue in developing country like India. Cities are growing on the pace never experienced before. Environmental deprivation along with resource depletion is more concentrated in the cities. Urban Sustainability approach is proposed by compact city planning which is categorized by high density planning, mixed land use and efficient urban mobility. India is still lacking in this kind of concept to be not only studied but also implemented. It is essential to discover the relation between the density and urban sustainability as India is the nation with high population density. The aim of this study is to find out a nature of relationship between population density and urban sustainability.

Keywords: Compact city, Urban sustainability, High density planning, India

Introduction

Excess exploitation of resources as well as rapid growth of population is the reason due to which sustainability has became the essential element of planning. Bruntland Commission (1983) described Sustainable Development as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs”. The need of Sustainable Development actually started after Earth Summit held at Rio-de Janeiro in 1992. Before this Earth summit UN assembly organized as conference on the human Environment at Stockholm in 1972 and also conference on the issues concerning depletion of natural resources and unsustainable development. The action plan named ‘Agenda 21’ was adopted in earth summit. ‘All the major world conferences and initiatives taken so far on environment and development have stressed on economically viable development, socially equitable development and protection of the environment for attaining sustainable development’ (Basudha Chattopadhyay, 2008).

Urban sustainability is further more complex issue to handle. ‘Sustainable urban development specifically means achieving a balance between the development of the urban areas and protection of the environment with an eye to equity in employment, shelter, basic services, social infrastructure and transportation in the urban areas’ (Basudha Chattopadhyay, 2008).  Cities with their rapid growth are becoming more and more complex. ‘… the complexity of, urban forms’ (Yu-Hsin Tsai, 2005). There are problems of housing, land value, green spaces, pollution, urban mobility, economic, social aspects.

The aim of this study is to explore the nature of relationship between Population Density and Urban Sustainability. In this study Compact City planning concept has been considered to achieve Urban Sustainability. ‘Compact city planning is taken to mean a relatively high-density, mixed-use city, based on an efficient public transport system and dimensions that encourage walking and cycling’ (Burton, 2000). Density is one of the tools which are used for planning and also in development regulation. In this study high-density aspect is considered out of the three aspects of compact city planning. Population density is used as tool for Urban Sustainability. The reason to choose density as tool is because, ‘protagonists see higher residential density as a necessary component of a compaction policy’ (Breheny, 2001). The density is the quotient obtained by dividing the population by the area. Sustainability (or Urban Sustainability) in this study is measured through various environmental and socio-economic variables.

There are two stages of this study

1.      To study the interaction between population density and selected variables affecting Urban Sustainability

2.      To study the nature of the relationship between density and AEP of selected study area.

This study is divided in to two parts with respect to the study area;

v  First part includes the study of both the above stated objective using four different cities in Maharashtra namely Nashik, Aurangabad, Pune and Nagpur.

v  Second part all the ten zones of Nagpur city has been selected as study area with the same aim and objective.

Because of limited time period and also non-availability of few data, only certain indicators of Urban Sustainability have been selected. The selected variables are broadly classified as environmental externalities, infrastructure efficiency, public transport, facility availability. These variables are selected because density has close relation with the human activities in urban areas. Capello and Camagni stated ‘with the increase of density and the concentration of human activities, it helps to exploit economies for public services and environmental resources’.

Few cases have been studied and two more relevant case studies have been mentioned. The case studies are from European and Oriental part. In India there isn’t any detailed work on Compact City Planning, whereas ‘compact city planning is hottest topic in the international environmental agenda’ (Chen, Jia, Lau, 2008) Out of the two case studies in the Oriental example they have selected 45 Chinese Cities and tested the relationship between urban compaction with Agglomerated Environmental Performance (AEP) which is nothing but representing the Urban Sustainability. In conclusion the study concludes that there is a relation between Urban Sustainability and urban Compaction.

The data has been collected from various sources such as CDP of cities for the first part. For the second the data from various department of NMC is used for this study. This data includes Population, Area, Density and other data regarding environmental externalities, infrastructure efficiency, public transport, facility availability.

The study as stated earlier is done for the two study areas. For both the parts same technique has been used. The variables selected after the data collection is correlated individually with the Population Density to discover the relationship between those variables and Population Density. The Pearson’s Correlation Method of Statistics has been used. There has been found out that there is adequate correlation between those variables and Population Density. The correlation found out to be positive as well as negative for most of the variables. Also there is slight correlation found in few variables. ‘Many studies have been developed for exploring interaction between selected environmental variables and urban compaction’ (Chen, Jia, Lau, 2008). The general arguments are ‘with the increase of density and the concentration of human activities, it helps to exploit economies for public services and environmental resources’ (Capello & Camagni, 2000). However, an excessive concentration of activities and proximities may result in aggravated negative environmental externalities and overcrowding (Chen, Jia, Lau, 2008)

As urban compaction has been found to be beneficial for some environmental aspects but harmful to others, an in depth investigation of the relationship between urban compactness and AEP is needed’ (Chen, Jia, Lau, 2008). At the second stage of the study the correlated variables are standardized in one index using the Z score Analysis which is represented as AEP of the study area (city as well as zone). Best Fit Analysis is then carried out using IBM SPSS 19 to explore the nature of relationship between Population Density and AEP representing Urban Sustainability. The Best fit model obtained advocates a positive relation between AEP and Population Density. But after certain optimum level this relation becomes negative.  This finding appears consistent with many established arguments that ‘an environment has a limit or capacity up to which it can absorb activities without irreparable harm’ (Entac, 1997)

From the study it is found out that the gross population density of Nagpur city 97.84 persons per hectares which less than the optimum values discovered through study i.e. 130 persons per hectares. As per the UDPFI Guidelines the density of city like Nagpur should 100 -130 persons per hectares. There is scope for Nagpur city for further densification. In the second part if the optimum density is compared with the existing density of the zones of Nagpur. Out of 10 zones of Nagpur five zones need densification and other five zones with needs de-densification. This study needs to be further carried out considering more factors affecting Urban Sustainability. The high density planning must be inclusive of mixed land use planning and urban mobility aspects of the Compact City Planning.

Even though there are indications concerning the advantages innate in high density urban form-It is also important to understand that merely increasing density and controlling the size of our cities is not the solution. Vital urban design issues like adequate open public space and pedestrian friendly streets need to address to deliver the true benefit of the compact city concept.

The first part of the study had shown us that there is a relation between the various environmental and socio-economic variables with the population density of Nagpur city. Further the second part through Best Fit Analysis gave us the optimum density as 130 persons per hectares. The relation between AEP and Population Density becomes negative after this optimum density value of 130. To lead towards urban sustainability there is need to have a balance in the Population Density of Nagpur city. Figure 6.2 shows that there is scope of increasing the gross density of Nagpur city. Forcing a compact city policy on the future urban planning is feasible (Chen, Jia, Lau, 2008). If we consider the UDPFI Guidelines* for a city like Nagpur which is developed on the plain the density expected ranges from 100 to 150 persons per hectares. Increasing the density of Nagpur as a whole as well as zones of Nagpur (which have lower density than 130 persons as stated above) is not only reasonable but also expected.

In figure 6.2 the existing density of all zones is compared with the optimum value of density i.e. 130 persons per hectares. The blue colored bar indicates existing density and the yellow colored bar indicates the difference in the density of each zone. It is observed that in the zone number 1, 2, 8, 9 and 10 (Laxmi Nagar, Dharampeth, Lakkadganj, Aasi Nagar, Mangalwari Bazaar respectively) have scope for increasing the density whereas the zone number 3, 4, 5, 6 and 7 (Hanuman Nagar, Dhantoli, Nehru Nagar, Gandhi Bagh, Satranjipura respectively) have much more high density so they might need of de-densification. From here on there would be a need to find out the different ways of densification or de-densification.

Increasing density may lead to chaotic situation if the other aspects of Compact City Planning are not considered simultaneously. Generally three aspects of the compact city are identified: a high-density city, a mixed-use city, and an intensified city (Burton, 2002). The high density planning needs to be intertwined with the mixed land use planning and the urban mobility. Compact city planning is taken to mean a relatively high-density, mixed-use city, based on an efficient public transport system and dimensions that encourage walking and cycling (Burton, 2000).

High density development needs a thorough research in all the above stated and also other related aspects. There cannot be a concrete conclusion to a planning project but a lead for further research. This whole study gives us an idea that density has a relation with various factors affecting Urban Sustainability. The optimum density at which the city might be a sustainable is 130 persons per hectares. There is a positive relation between AEP and Population Density. The AEP increases with the increase in the Population Density till the optimum value of 130 persons per hectares. After this optimum level the relation becomes negative. In the city of Nagpur the gross density is 97.84. There is a scope to increase the density of Nagpur city. Out of ten zones of Nagpur few zones needs de-densification and others needs densification. The zones and the city should be made with equal optimum density which is favorable to the Urban Sustainability. High density planning is need of today to achieve Urban Sustainability. High Density Planning should not be considered in isolation but should be inclusive of other aspects of Compact city planning i.e. Mixed Land Use Planning and Urban mobility. This would definitely escort us towards Urban Sustainability.