Characteristics of urban heat island, local climate zone classification and strategies for Bangkok | |
| Author | Dararat Khamchiangta |
| Call Number | AIT Diss no.ET-20-02 |
| Subject(s) | Urban heat island--Thailand--Bangkok Climate--Thailand--Bangkok |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Energy, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. ET-20-02 |
| Abstract | The phenomenon of Urban heat island (UHI) can be found in many cities around the world. Bangkok Metropolitan Administration (BMA), Thailand is one of cities facing this problem. Heat intensity in Bangkok is a serious problem, but BMA has not provided any specific plan or strategies to mitigate the warming in the city. In addition, the studying of warming contributors and urban heat island phenomenon has been addressed in less comprehensive way in the existing literature. Therefore, the overall examination of this research is to understand the characteristics of urban heat island phenomenon and identify the potential strategies for mitigating local warming in Bangkok. New approach such as local climate zone (LCZ) can help better understand the current situation of UHI, driving factors, and future land use changes. This knowledge could guide the city authorities in framing the potential mitigation strategies in BMA. The overall of this research is divided into four major parts. Firstly, the study focuses on time series analysis of land use and land cover (LULC) characteristics and its relationships with UHI intensity in BMA area. LULC classification based on satellite images taken by Landsat data in summer dates of 1991, 1997, 2005 and 2016, were classified into four LULC types: (1) Built up area; (2) Vegetation area; (3) Barren land; and (4) Surface water. UHI was studied by deriving Land Surface Temperature (LST) based satellite images method using the thermal band of Landsat satellite in the same periods as of LULC classification. UHI intensity (ΔT), in this study, was estimated as the difference between maximum and minimum temperature of LST in the study period. The result shows that over study period, built up area continually expanded from city center to surroundings. The urbanization remains low in the eastern part of Bangkok due to the limitation of accessibility development plan, green zone regulation of BMA zoning plan and no connection area to Bangkok Metropolitan Region (BMR). UHI intensity was also continually rising from 11.91°C in 1991 to 16.21°C in 2016 leading to nearly 5°C increase in Bangkok. High density of buildings, no vegetation areas and large area of concrete pavement are the most significant related to the hot spot areas. Secondly, the research examines two aspects of the urban heat island (UHI) in Bangkok. First, the study is aimed at examining the difference in temperature between zones that are classified into different built areas and other land cover types instead of simply using the urban and rural classification, which is prevalent in the existing literature. Second, the study considers the heat-intensity-related physical structure of the city such as the sky view, building coverage, building height, surface albedo, and pervious and impervious surfaces, as well as non-physical factors such as anthropogenic heat, travel demand, electricity consumption, and air pollutant concentration. The local climate zone (LCZ) is used as an approach for characterizing the landscape and physical structure of the study areas. The examination used 2016 as the base year for the analysis. The LCZ is classified using Landsat data and the training areas are created using Google Earth and Google Street View. The heat intensity is studied by deriving the land surface temperature (LST) from the thermal band of the Landsat satellite images of March 3, April 4, and April 12, in 2016, which represent the summer season in Bangkok. The result shows that the “industry building areas” have the highest mean LST is 32.41 °C, while the lowest LST is 28.32 °C in areas of water bodies; the temperature difference was approximately 4 °C. The factors significantly influencing the warming in the BMA are pervious and impervious surfaces, the building coverage ratio, and the anthropogenic heat flux, while the sky view factor, vehicular traffic, and air pollutant concentration are the weak drivers of UHI. Thirdly, the research focuses on land use and LCZ changes in relation to warming in the future, the study concentrates on three major parts. First, this research analyzes LULC and LCZ changes from 1991 to 2016 using Landsat satellite images data. This reveals the history of urban expansion over the study period, urban growth rate and urban land demand projection in the target year. Second, the study determines LULC and LCZ changes in the future by using SLR model with three considerable driving forces: (1) neighborhood factor; (2) accessibility factor; and (3) physical factor. SLR modelling calculates a logistic regression coefficient between various spatial distributors and the developed built-up area cells in the past to explore the probability of a given location that becomes the built-up area in the future, then simulates land use change in the target year (2026). Third, the examination of urban expansion in relation to warming in the future was conducted. The result shows that the built-up area has more development and expansion to the northern, southern and western parts of Bangkok due to transportation network, Bangkok Metropolitan Rapid Transit (BMRT) development project and the improvement of transportation connectivity with neighboring provinces known as Bangkok Metropolitan Region (BMR) area. The builtup surface temperature climbed and continued to increase between 1991 and 2016. The trend of temperature differences between the built-up areas and other areas such as vegetated and water bodies, significantly widened in 2026. According to the prediction of LCZ expansion, most of green area on the western part of Bangkok was replaced by compact mid-rise, compact low-rise, and open low-rise building. The study means that the western part of the city will be warmer approximately 1 to 2 °C in the future. Bangkok will be facing more serious warming in the future if this large green area disappears and no mitigation action is taken. Finally, this research used pairwise comparison to study the possibility of strategies for implementation to mitigate warming in the city. Based on analysis related the characteristics of UHI, the key factors driving warming, and the future urban expansion in Bangkok, the potential mitigation strategies were divided into two group, the first group is the voluntary strategy included 3 strategies: (1) pilot projects; (2) incentive strategies; and (3) building award projects. The second group is the policy strategies which included 6 strategies: (1) transportation system improvement; (2) capacity building; (3) green area expansion; (4) zoning code and land use planning; (5) building code; and (6) urban cap and trade. This pairwise comparison analysis required expert judgement to rank the strategy that easy and possible to implement in Bangkok. This research collected data from 16 experts, covering various backgrounds and experience. Sixteen experts are from Department of Public Work and Town & Country Planning in BMA (3 experts), Industry Estate Authority of Thailand (2 experts), Corporate Social Responsibility (CSR) section of private sector (4 experts), low carbon city, transportation, and climate change researcher (7 experts). As a result, this study provides a framework for strategies implementation timeline which is constructed and integrated from the ranking of the key factors driving high temperature and the ranking of the strategies that are easy to implementation. The framework is divided into three time frames as short, medium, and long-term for implementation, ranking form the easy implementing project to the plan that required long time frame for effective and successful implementation in Bangkok. The main knowledge contribution of this research is to build a comprehensive understanding of urban heat island for academic community, build the public concern about local warming problem and guide the city authorities to frame the potential mitigation strategies for implementation in Bangkok. This research has constructed an assembly different models and methods for studying urban heat island. The assembly technique was employed in this research is unique and contain a comprehensive process, despite the individual methodology is well practiced. The contribution in this research methodology is critical for boosting and improving for other case studies. |
| Year | 2020 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. ET-20-02 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Dhakal, Shobhakar; |
| Examination Committee(s) | Kim, Sohee Minsun;Shrestha, Rajendra Prasad;Yoshiki Yamagata; |
| Scholarship Donor(s) | Royal Thai Government;Asian Institute of Technology Fellowship |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2020 |