Carrying capacity based planning for allocation of development densities in urban areas : a case of Bengaluru

Abstract

This thesis titled “Carrying Capacity Based Planning for Allocation of Development Densities in Urban Areas – A Case of Bengaluru” is done as a part of Bachelor of Planning Programme. India with an urban population of more than 377 million, is projected to have more than 50% population residing in urban areas by 2050. Urban centers considered to be the catalyst behind the comprehensive economic development of the nation are now manifesting severe depression in the form of over-concentration of the population, inadequate infrastructure, depleting natural reserves, high levels of pollution and deteriorated quality of life. Increasing rates of urbanization and subsequent increase in urban issues have posed a challenge to the policy makers and planners for effective planning and management of urban areas. In the past decade, the Indian government has shifted its focus on policies related to urban governance, inclusive growth, climate resiliency, and affordable housing, etc. to solve the emerging issues. Compact city is one such concept which prescribes high-density development in order to resolve urban planning issues of congestion, long travel times, high vehicular trip rates, the involvement of opportunity costs due to delays in travel and pollution due to carbon emissions. Here, density plays an important role. Since development density decides the bulk of built space in an area, it affects other aspects of planning such as reachability to goods and services, the mobility pattern, the urban form of the city, and economic viability to use the available resources. Sustainable Development is another concept rooted back to the seventeenth century. It acknowledges the demands of the future generation while catering to the needs of the present generation. It also takes into account the amount of development activities which can be taken out within the physical and environmental barriers present within the ecosystem. Combining the above notions of compact development and sustainable development, we have another concept of carrying capacity which originates from ecology. It aims to define the optimum limit of the population which can be efficiently sustained in a delineated geographic area without damaging the natural and social habitat of that area. Thus it helps in deciding the optimum population density which can be viable for the existing infrastructure to support. There lies a common prenotion behind this concept i.e. the carrying capacity in regard with any given area cannot be fixed and it can always be enhanced by technological developments or by the addition of assets. The concept of carrying capacity probe into the sustainability aspects of the technological advancement and questions the viability of such technologies for the future generation. Researchers have devised numerous models and methods to assess the carrying capacity with an aspiration to solve diverse urban problems, but the application of these models in the Indian context has not been studied thoroughly. In the purview of achieving sustainable development, this thesis aims to evaluate methods for allocation of development density in urban areas through the appropriation of carrying capacity of the area. In order to understand the applicability of the concept and figuring out its correspondence with the ground reality, various models and methods involving evaluation of carrying capacity were reviewed. After reviewing all the models and methods, Sustainable Accommodation through Feedback Evaluation (SAFE) Model, developed by IIT Guwahati was used in the study, since it is the only model which explores the carrying capacity in terms of actual population value. As the name suggests, the model facilitates to allocate a sustainable population through analyzing feedback of the initially allocated population. The formula prescribed by the model to estimate the carrying capacity of an area is as follows: Carrying capacity= [AU – (AND + AIF)] x FAR/S where, AU = Total Urban Area, AND = Non-Developable Area, AIF = Area for Infrastructure, FAR = Average Floor Area Ratio, and S= Floor Area per Head. Bengaluru, being the only metropolis in the state of Karnataka, encompasses the characteristics of a primate city. High quantum of in-migration due to booming economic activities have contributed to the issues of congestion, lack of open spaces, stressed infrastructure and environmental pollution and is expected to hamper the growth of the city in the future. Thus the city was found pertinent for the study involving carrying capacity based allocation of development densities. The SAFE model was applied on different zones of Bengaluru. The land use data was inserted into the formula to give the trial carrying capacity for each zone. It was found that the zones located in the core of the city, due to high density, upscaled commercial activities and high consumption rates had less carrying capacity as compared to their existing population. Feedback of the trial allocated population was evaluated by comparing the land area required for physical infrastructure (Water Treatment Plant, Ground Level Storage Reservoir, Sewage Treatment Plant and Landfill), social infrastructure (education, healthcare, socio-cultural facilities, open spaces), miscellaneous facilities (telecommunication, postal and banking services) and commercial areas, with the land available for such infrastructure. The required land was assessed using URDPFI norms for land area requirements for different infrastructures. For zones having an available area less than the required area, trial carrying capacity was adjusted to give us the safe carrying capacity and subsequently logical FAR for each zone was computed. It was observed that the results were similar, i.e. the zones located in the core of the city due to less availability of net residential land for development and simultaneously having a high population, have already exceeded their carrying capacities whereas, in the peripheral zones, there was a scope for more population. This was followed by generation of different scenarios for distribution of FAR in the study area. Based on the existing development pattern and the growth strategies established by the development plans, four scenarios were generated viz. Business as usual scenario, Scenario of Flat FAR across the municipal limits, Scenario of Transit Corridor Development, and Scenario of FAR based on the distance from the city center. The criteria used to validate and find the most preferred scenario were: firstly, the safe carrying capacity should be greater than the existing population and the average FAR value should be less than the maximum FAR in each zone. Although, the scenario of Flat FAR was found to be the most preferable scenario but the scenario analysis revealed that in none of the cases, it is possible to increase the safe carrying capacity of all the zones so that it is more than the existing population of the zone. Thus we conclude from the analysis that the FAR in-spite of having a direct relationship with the trial carrying capacity, is weakly related to the safe carrying capacity. Rather the safe carrying capacity is dependent on the available land for infrastructure. So if we need to achieve certain safe carrying capacity for a particular zone, we can either augment our available land for infrastructure by increasing amount of vacant land through displacement of the population or we could lower the amount of land area required for infrastructure through technological developments. Moreover, a critical appraisal of the SAFE model was done and it was concluded that the SAFE model is not suitable to be applied on a large area since a lot of field work is required to assess the different parameters used in the formula and for feedback evaluation. Lastly, this thesis explores ways of achieving the value of carrying capacity which is greater than the existing population. The zones with a population exceeding their respective carrying capacity have been studied in detail to know the amount of residential land which could be converted into vacant land in order to augment the carrying capacity. The calculations follow an assumption i.e. reduction in residential area will cause a proportional decrease in the area of infrastructures. Moreover, once the area under infrastructure is increased, the FAR in the remaining residential areas can be increased thus increasing the carrying capacity of the zone. This thesis also recommends development planning process to involve practical approaches of carrying capacity based allocation of development densities, in order to promote the sustainable and regulated development of the urban areas.