Urban Ecology
Elham Ghasemi; Zahra Nazemi; Safoura Mokhtarzadeh; Mahdi Suleimany
Abstract
Highlights:
- Investigates the correlation between environmental factors and UHI intensity in the Isfahan metropolitan area over 10 years.
- Utilizes MODIS Aqua & Terra data alongside Landsat 8 imagery for comprehensive UHI analysis.
- Establishes a significant relationship between UHI ...
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Highlights:
- Investigates the correlation between environmental factors and UHI intensity in the Isfahan metropolitan area over 10 years.
- Utilizes MODIS Aqua & Terra data alongside Landsat 8 imagery for comprehensive UHI analysis.
- Establishes a significant relationship between UHI and urban built density, vegetation, and water features.
- Determines vegetation as the most influential factor in mitigating UHI compared to other elements.
- Highlights the vital role of natural infrastructure in urban planning for UHI mitigation.
Introduction:
The Urban Heat Island (UHI) effect, characterized by a temperature increase in urban areas compared to their rural counterparts, presents considerable environmental challenges, impacting public health, urban energy systems, and city sustainability. This phenomenon, fueled by rapid urbanization and industrialization, exacerbates heatwaves, posing risks to public health. Understanding the UHI effect is essential for developing responsive urban planning strategies both spatially and institutionally. This study, centered on Isfahan, Iran, explores the correlation between UHI intensity and environmental factors, encompassing both built and natural attributes across five scenarios, including four seasons and one analyzing the ambient effect of the ZayandehRud river.
Theoretical Framework:
The UHI phenomenon involves complex interactions among various urban and environmental factors. The density of the built environment contributes to UHI exacerbation through heat storage and anthropogenic heat discharge. Air pollution, especially with greenhouse effects, directly influences heat-trapping and UHI formation. Conversely, green infrastructure and water bodies offer UHI mitigation through cooling effects. This study integrates theoretical basics from urban planning, climatology, and sustainable development for an analysis of how both natural and built elements correlate with UHI intensity in the Isfahan metropolitan area.
Methodology:
A mixed-method approach is adopted to address the multifaceted nature of Urban Heat Island (UHI) and its potentially correlated environmental factors. Land Surface Temperature (LST) data, crucial for delineating UHI, were extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard NASA's Aqua and Terra satellites, covering a decade from 2011 to 2021. This extended timeframe facilitates the exploration of UHI patterns across various seasons, examining specific impacts during both the flow and dry periods of the ZayandehRud river, as well as distinguishing LST differences between daytime and nighttime periods—unlike Landsat Satellite Images.
Additionally, Landsat 8 images are utilized to process the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) for mapping green infrastructures and water bodies. Air Quality Index (AQI) data from the year 2020 supplements the study, allowing for an investigation into the relationship between air pollution and UHI. The analysis of all datasets employs the Pearson correlation coefficient to ascertain the nature and extent of correlation among UHI and the identified environmental variables.
Results and Discussion:
The findings reveal the persistent prevalence of Urban Heat Island (UHI) during nighttime across all scenarios in Isfahan. However, during daytime hours, the trend shifts, giving rise to cooler zones within the city borders, indicating the emergence of urban cold islands. A noteworthy revelation from the study is the significant exacerbation of UHI attributed to the density of the urban built environment. Intriguingly, air pollution, though exerting a lesser impact on Land Surface Temperature (LST) compared to built density, still plays a role in elevating LST during daylight.
The study underscores the pivotal role of urban green infrastructure and water bodies in mitigating heat islands. Among these elements, green spaces, particularly vegetation, emerge as highly influential, surpassing the cooling effects of both water bodies and polluted air. The seasonal variation in vegetation cover also influences UHI intensity, with reduced vegetative cover in colder, drier seasons contributing to heightened UHI effects. These spatial and temporal dynamics emphasize the intricate balance between UHI and environmental factors, offering valuable insights for decision-makers. Such insights can guide targeted strategies in urban planning and design to address the challenges posed by UHI.
Conclusion:
The study emphasizes the importance of considering UHI in urban planning, design, and sustainability discussions. Strategies include reducing built density and integrating green and blue infrastructures. Addressing air quality and vegetation cover in shaping urban thermal landscapes suggests comprehensive policies. Guarding against UHI through natural space preservation and innovative design solutions tailored to Isfahan's climate can enhance urban livability. Future work should quantify contributions of different elements for comprehensive UHI mitigation models. This Isfahan case study serves as a cornerstone for wider applications across similar cities, aiding in combatting global warming and UHI effectively.
Urban Ecology
Hassan Mahmoudzadeh; Mousa Vaezi; Maedeh bakooyi; Rahimeh Rostami
Abstract
Objectives The evolution in industry in the eighteenth and nineteenth centuries led to greater human domination of the planet and the environment. In the field of clean environment, urban parks are regarded as an important element in creation of a sustainable city. They provide opportunities in various ...
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Objectives The evolution in industry in the eighteenth and nineteenth centuries led to greater human domination of the planet and the environment. In the field of clean environment, urban parks are regarded as an important element in creation of a sustainable city. They provide opportunities in various areas for instance by improving the environment quality, enabling active and passive entertainment, and creating a beautiful environment. Accordingly, thinkers have considered the strengthening of the relationship between the urban man and the nature as a major way of dealing with the problems of urbanization. Therefore, cities need particular attention today in terms of revival of the urban nature, as presence of the nature in the city, to the necessary extent, and its composition and distribution is a requirement of sustainable development. Evidence from Iran and the area under study in regard to current urban green space planning and design indicates that the idea of ecological design and planning is very weakly treated. Due to the dissatisfaction with the current conditions in the design of urban green spaces as an important part of the city, development of green spaces with high ecological efficiency, significant bioclimatic features in particular, should be considered. Findings In the ranking provided by the TOPSIS method, Elogli Park exhibits the lowest positive ideal (5.41) and the highest negative ideal (13.45), followed by the Shams, Baghmishe, and Eram parks, in that order. This is because the cli coefficient, the negative ideal divided by the sum of the positive and negative ideals, for Elogli Park (15.93) is higher than those for the other parks, assigning it the highest priority in ecological terms among the parks under investigation. The four studied forest parks were classified by ecological indicators using the electric model. According to the results obtained by this method, Elogli Park was ranked first in ecological terms, and the Shams, Baghmishe, and Eram parks were ranked next. A point to be noted concerned the improper conditions of the Baghmishe and Eram parks, the latter in particular, in terms of the indicators, calling for greater attention to these parks. Based on the data on vegetation density, Shams Park exhibited denser coverage than the other parks, followed by Elogli, Baghmishe, and Eram, in that order. The denser the vegetation, the higher the priority of the park, and the better its ecological conditions. According to the three indicators studied in the GIS environment, Shams Park was in better conditions in ecological terms than the other parks. Results The results demonstrated that today’s cities need multi-purpose ecological balancing spaces rather than gardens and lawn. The prioritization of the parks based on cultural criteria indicated that the Eram and Shams parks were in better conditions than Shahgoli and Baghmishe. Physically, Elgoli Park was found to hold the highest priority, followed by Shams, Baghmishe, and Eram, in that order. In environmental terms, the Elgoli, Shams, Baghmishe, and Eram parks were ranked in that order. In terms of access features, Baghmishe and Shams were ranked first, followed by Elgoli and Eram. Finally, Elgoli and Shams were both identified through combination of the maps for all the criteria according to their weights as the best parks in terms of accessibility and cultural, environmental, and physical features. They were followed by Baghmishe Park, and Eram exhibited the lowest score among the parks in terms of the above features.
