Graduate Research Symposium 2023
Urban Environment and Greenspaces
Time: 10:45AM – 12:20 PM
Venue: Seminar Barrel Room, SDE3 Floor2
Reviewers: Evi Syariffudin and Dorothy Tang
Speakers:
ZHOU ZUYUAN BRYNN
THE IMPACT OF NEIGHBOURHOOD GREENERY ON SOUNDSCAPE PERCEPTION IN SINGAPORE PUBLIC HOUSING AND RESIDENTIAL AREAS
Abstract: The quality of life is impacted significantly by the urban sound environment. A good sound environment promotes health and well- being, while a noisy sound environment can cause hearing loss and mental stress. Various noise control methods have been explored by researchers. In the last decades, an emerging approach has been to investigate through an audio-visual approach. Greenery, as one of the most significant components of the landscape, however, has been suggested to have little effect on soundscape perception.
This study argued that the previous approach used was not appropriate. We aim to introduce new indicators and explore whether neighbourhoods’ greenery has a sizeable effect on soundscape perception from a new perspective. Indicators introduced include typically used greenery coverage, Green View Index (GVI), openness, wildness, naturalness, etc. Panoramic photos and point clouds were introduced to calculate the greenery indicators. In addition, sound metrics were also employed, including Mask Duration of Natural sound, Loudness, Sharpness, Roughness, etc., to quantify the effect of greenery on the soundscape. We also studied the current conditions of soundscapes around Singapore’s public housing and residential areas and developed a predictive model based on the new indicators.
The results show that greenery’s species diversity, openness, and wildness correlate positively with overall soundscape perception. However, the overall impact of these indicators is not significant. A noticeable trend detected from the data is the impact of sound on overall landscape perception. Masked duration of natural sound shows an impressive positive impact on landscape perception. Sharpness, Loudness, and Roughness also showed a noticeable impact on landscape perception. These relationships lead to an unexplored area in audio-visual interaction studies-the impact of soundscape on landscape perception. It serves as a base for future soundscape research and practice.
CHEN TAIHAN
EFFECTS OF TREE PLANTINGS AND STREET ASPECT RATIOS ON THE THERMAL ENVIRONMENT USING A MECHANISTIC URBAN CANOPY MODEL UT&C
Abstract: Tree planting in urban areas has the potential to improve the urban thermal environment and mitigate the Urban Heat Island. Although the cooling effects of trees have been widely reported, the understandings of the integrated effects of street morphologies and tree parameters on the thermal environment are insufficient, especially in high-density cities. A parametric study is conducted to investigate the impacts of the tree leaf area index (LAI=1.0, 2.0, 3.0, 4.0, 5.0, 6.0) and crown radius (r_tree=2.0, 3.4, 4.4, 5.0m) on the thermal environment inside streets with various aspect ratios (street height/width, H/W=1.0- 5.0). We use the mechanistic urban canopy model Urban Tethys-Chloris (UT&C) (Fig. 1) and integrated a new semi-empirical wind parameterization into the model based on drag coefficients and frontal area densities of buildings and trees.
A unique scaled outdoor experiment (Fig. 2) is used to evaluate UT&C’s model performance through the comparison with pedestrian-level air temperature T_a, relative humidity RH, wind speed V, and thermal comfort indices (Mean Radiant Temperature T_mrt and Universal Thermal Climate Index UTCI). The results can be summarized as follows: (1) The integration of the new wind parameterization into UT&C significantly improves the performance of V calculation; (2) The calculated T_a, RH, and thermal comfort indices (T_mrt and UTCI) are in good agreement with measured results, while slight overestimation of RH occurs in streets with trees; (3) Maximum cooling effects of about 4.0℃ UTCI occur for LAI=4.0 and r_tree=3.4, 4.4, 5.0 m, and such cooling effects are weakened as H/W increases from 1.0 to 5.0; (4) LAI=4.0 and r_tree=5.0 m are found to be optimal for wide streets (H/W=1.0-3.0) to provide maximum UTCI cooling effects (about 4.0℃), while LAI=4.0 and r_tree=3.4 m are optimal for narrow streets (H/W=3.0-5.0). The above research outputs can provide guidelines for architects and planners on urban tree selection strategies.
QIU YESHAN
COMPARATIVE ECOLOGY OF CITIES: UNDERSTANDING THE IMPACT OF URBAN PATTERNS ON URBAN AVIAN BIODIVERSITY
Abstract: Urban avian biodiversity (UAB) is essential for maintaining ecosystem health, providing ecological services, and enhancing urban residents’ well-being. Nevertheless, rapid urbanization and habitat loss pose significant threats to avian biodiversity. To mitigate these threats, understanding the role of urban patterns in affecting UAB becomes crucial. This research aims to address critical knowledge gaps by employing a comparative approach across multiple cities to study the influence of urban patterns on avian biodiversity. The study will follow four main steps. Firstly, comprehensive datasets of avian biodiversity will be collected from citizen science initiatives in various cities. Secondly, relevant urban pattern metrics, such as green spaces, built-up areas, water bodies, and land use heterogeneity, will be determined. Thirdly, statistical analysis and modeling will explore the relationships between urban patterns and avian biodiversity within and among cities. Lastly, generalizations and recommendations will be drawn to inform urban planning strategies for promoting biodiversity conservation.
Preliminary findings based on within-city comparison approaches, such as grids, urban typology using Local Climate Zones (LCZ), and buffer analysis, have yielded certain insights in the case study in Singapore. Notably, a grid cell size of 2km appears suitable for studying the “urban pattern-UAB” effect. Significant relationships have been identified between urban patterns and avian biodiversity metrics. For instance, Total Canopy Area (TCA) and Canopy Height (CH), Building Height (BH) are positively associated with avian abundance, while the Nearest Distance to Water Body (Water_ND) positively influences avian biodiversity. On the other hand, Building Volume (BV) and Water Shape Index (the complexity of water body shape, WSI) show negative associations with avian biodiversity. Urban typology analysis revealed that built-up areas had a greater effect on the abundance and richness of these functional guilds compared to natural areas. This suggests that the spatial pattern and characteristics of built-up areas may play a potential role in influencing UAB. The tentative results indicate potential trade-offs and complementarity between the different within-city level approaches, which will be further explored in multiple cities.
Through within-and across-city spatial analysis in numerous cities, this research aims to comprehensively examine the “urban pattern-UAB” effect. By identifying key drivers and urban morphology metrics influencing UAB, the study seeks to inform sustainable urban development and promote biodiversity conservation efforts. The outcomes aim to have broad implications for creating resilient, livable, and bio-friendly cities of the future.
GU TIANTONG
HOW AND WHY ‘NATURE’ BECOME AN URBAN SOLUTION AND IDEAL URBANISM?
Abstract: This study examines the unique trajectory of Singapore’s urbanization, juxtaposed against the global trend of urban naturalization, to unravel the strategic role of ‘nature’ in the city-state’s quest for a concrete utopia. Globally, there’s a prevailing belief that bringing ‘nature’ into cities is essential for future prosperity, suggesting that historically, urban development has often sidelined the natural environment. Singapore’s approach, however, stands out. Here, ‘nature’ is not an afterthought but an active co-evolving participant in the process, woven into the very fabric of social-political-economic transition. This research raises the ‘question of nature’ and adopts Singapore as a case study to dissect how ‘nature’ is strategically selected and folded into urbanization process for transitioning the society to urban society and towards a concrete utopia?
By posing the ‘question of nature,’ this investigation is guided by Henri Lefebvre’s theoretical framework, which posits the society has been completed urbanized as urban society, the urban as a product of urbanization, and the production of space as a conceived, physical, and lived reality. The concept of ‘utopia’ is critically examined as a driving force behind state’s intention on urban-nature integration. Methodologically, the study employs a nested approach, predominantly qualitative, with quantitative data providing supportive contextualization. The research unfolds in two principal parts: 1) Producing and Reproducing ‘Nature’ – a joint process of Urbanization process in Singapore. 2) Urban-Natural as a concrete utopia – a collective project between state and people. This research further contributes to the discourse on urban-nature relations by showcasing the potential for a co-evolution and its implications for the future of urban society.