scholarly journals Influence of Spatial Characteristics of Green Spaces on Microclimate: A Case Study in Suzhou Industrial Park, China

2021 ◽  
Author(s):  
Xiangdong Xiao ◽  
Lulu Zhang ◽  
Yimei Xiong
Keyword(s):  
Urban Heat Island ◽  
Green Space ◽  
Green Spaces ◽  
Medium Size ◽  
Industrial Park ◽  
Air Cooling ◽  
Heat Island ◽  
Local Cooling ◽  
Urban Green Spaces ◽  
Urban Heat

Abstract Continuous urban development leads to urban heat island effects. Research suggests that urban green spaces can help effectively reduce urban heat island effects in the summer. Previous studies have mainly focused on the influence of different underlying surfaces on air cooling and humidification. There is a lack of in-depth research on the relationship between park structure and microclimatic effects. Here, we examined the main landscape parameters of green spaces in 15 parks located in Suzhou Industrial Park (SIP) with a subtropical maritime monsoon climate zone during the summer to analyze their influence on the microclimate. The average cooling and humidifying effect of medium-size green spaces was most significant during high-temperature hours in the daytime. When the distance to a water body was the same, the average cooling and humidifying effect ranked as follows: large-size green space > small-size green space > medium-size green space. We explored the mechanisms of the local cooling and humidifying effects of woodland and water areas in parks by numerical simulations. The significance of the cooling and humidifying effects of water areas of different shapes was as follows: annular water > massive water > banded water. This confirmed that the shape and size of water areas within a green space has a significant influence on local cooling and humidification.

Conversion of Abandoned Property to Green Space as a Strategy to Mitigate the Urban Heat Island Investigated with Numerical Simulations

2020 ◽  
Vol 59 (11) ◽  
pp. 1827-1843
Author(s):  
Timothy J. Cady ◽  
David A. Rahn ◽  
Nathaniel A. Brunsell ◽  
Ward Lyles
Keyword(s):  
Numerical Simulations ◽  
Urban Heat Island ◽  
Green Space ◽  
Green Spaces ◽  
Heat Island ◽  
Impervious Surfaces ◽  
Vacant Lots ◽  
Local Cooling ◽  
Aggressive Approach ◽  
Urban Heat

AbstractImpervious surfaces and buildings in the urban environment alter the radiative balance and surface energy exchange and can lead to warmer temperatures known as the urban heat island (UHI), which can increase heat-related illness and mortality. Continued urbanization and anthropogenic warming will enhance city temperatures worldwide, raising the need for viable mitigation strategies. Increasing green space throughout a city is a viable option to lessen the impacts of the UHI but can be difficult to implement. The potential impact of converting existing vacant lots in Kansas City, Missouri, to green spaces is explored with numerical simulations for three heat-wave events. Using data on vacant property and identifying places with a high fraction of impervious surfaces, the most suitable areas for converting vacant lots to green spaces is determined. Land-use/land-cover datasets are modified to simulate varying degrees of feasible conversion of urban to green spaces in these areas, and the local cooling effect using each strategy is compared with the unmodified simulation. Under more aggressive greening strategies, a mean local cooling impact of 0.5°–1.0°C is present within the focus area itself during the nighttime hours. Some additional cooling via the “park cool island” is possible downwind of the converted green spaces under the more aggressive scenarios. Although moderate and conservative strategies of conversion could still lead to other benefits, those strategies have little impact on cooling. Only an aggressive approach yields significant cooling.

scholarly journals Spatial Analysis of Surface Urban Heat Islands in Four Rapidly Growing African Cities

2019 ◽  
Vol 11 (14) ◽  
pp. 1645 ◽  
Author(s):  
Matamyo Simwanda ◽  
Manjula Ranagalage ◽  
Ronald C. Estoque ◽  
Yuji Murayama
Keyword(s):  
Urban Heat Island ◽  
Green Space ◽  
Urban Landscape ◽  
Impervious Surface ◽  
Green Spaces ◽  
Heat Island ◽  
Impervious Surfaces ◽  
African Cities ◽  
Urban Rural ◽  
Urban Heat

Africa’s unprecedented, uncontrolled and unplanned urbanization has put many African cities under constant ecological and environmental threat. One of the critical ecological impacts of urbanization likely to adversely affect Africa’s urban dwellers is the urban heat island (UHI) effect. However, UHI studies in African cities remain uncommon. Therefore, this study attempts to examine the relationship between land surface temperature (LST) and the spatial patterns, composition and configuration of impervious surfaces/green spaces in four African cities, Lagos (Nigeria), Nairobi (Kenya), Addis Ababa (Ethiopia) and Lusaka (Zambia). Landsat OLI/TIRS data and various geospatial approaches, including urban–rural gradient, urban heat island intensity, statistics and urban landscape metrics-based techniques, were used to facilitate the analysis. The results show significantly strong correlation between mean LST and the density of impervious surface (positive) and green space (negative) along the urban–rural gradients of the four African cities. The study also found high urban heat island intensities in the urban zones close (0 to 10 km) to the city center for all cities. Generally, cities with a higher percentage of the impervious surface were warmer by 3–4 °C and vice visa. This highlights the crucial mitigating effect of green spaces. We also found significant correlations between the mean LST and urban landscape metrics (patch density, size, shape, complexity and aggregation) of impervious surfaces (positive) and green spaces (negative). The study revealed that, although most African cities have relatively larger green space to impervious surface ratio with most green spaces located beyond the urban footprint, the UHI effect is still evident. We recommend that urban planners and policy makers should consider mitigating the UHI effect by restoring the urban ecosystems in the remaining open spaces in the urban area and further incorporate strategic combinations of impervious surfaces and green spaces in future urban and landscape planning.

Quantifying the effects of urban vegetation on water partitioning in complex cityscapes: the potential of isotope-based ecohydrological models

2020 ◽  
Author(s):  
Mikael Gillefalk ◽  
Dörthe Tetzlaff ◽  
Reinhard Hinkelmann ◽  
Lena-Marie Kuhlemann ◽  
Aaron Smith ◽  
...  
Keyword(s):  
Urban Heat Island ◽  
Groundwater Recharge ◽  
Water Use ◽  
Green Spaces ◽  
Heat Island ◽  
Urban Green ◽  
Urban Green Spaces ◽  
Island Effect ◽  
Water Partitioning ◽  
Urban Heat

<p>The continued global acceleration of urbanisation increasingly requires sustainable, adaptive management strategies for land and water use in cities. Although the effects of buildings and sealed surfaces on urban runoff generation (via storm drains) and local climate (through the urban heat island effect) are well known, much less is known about how these artificial influences integrate with water partitioning in more natural urban green spaces. In particular, little is quantitatively known about how different types of urban green spaces (lawns, parks, woodland etc.) regulate the partitioning of evaporation, transpiration and groundwater recharge. To address this crucial issue, we integrated field observations with advanced, isotope-based ecohydrological modelling at the plot scale in the urban area of Berlin, Germany. Measurements of soil moisture, sap flow, and stable isotopes in precipitation, soil water and groundwater have been made over the course of one growing season. Additionally, an eddy flux tower at the site Rothenburgstraße in Berlin-Steglitz continuously collects hydroclimate data by measuring temperature, precipitation, radiation, humidity and wind speed at high temporal resolution. These data (30-min averages) have been used as input to, and for calibration of, the process-based ecohydrological model EcH<sub>2</sub>O-iso. The model also tracks stable isotope ratios and water ages in various stores (e.g. soils and groundwater) and fluxes (evaporation, transpiration and recharge). EcH<sub>2</sub>O-iso has successfully been used to describe the effects of vegetation cover on water partitioning in a number of studies but this is the first implementation in an urban setting. It shows that ecohydrological water use by vegetation type increases in the order forests > shrubs > grass, mainly through higher interception and transpiration. Accordingly, trees can reduce groundwater recharge by >50%, but provide cooling latent heat transfers to the atmosphere.  Similarly, ages of stored water and fluxes are generally greater under trees than grass. The results, which form the basis for future upscaling, show that urban green spaces play an important role in urban hydrology and in Berlin there is a trade-off between moderating the urban heat island effect and maintaining groundwater recharge. Consequently, it is clear that vegetation management needs to be considered in sustainable water and land use planning in urban areas to build resilience in cities to climatic and other environmental change.</p>

scholarly journals Interaction of Urban Rivers and Green Space Morphology to Mitigate the Urban Heat Island Effect: Case-Based Comparative Analysis

2021 ◽  
Vol 18 (21) ◽  
pp. 11404
Author(s):  
Yunfang Jiang ◽  
Jing Huang ◽  
Tiemao Shi ◽  
Hongxiang Wang
Keyword(s):  
Spatial Structure ◽  
Urban Heat Island ◽  
Green Space ◽  
Green Spaces ◽  
Marginal Effect ◽  
Heat Island ◽  
Island Effect ◽  
Urban Heat ◽  
Connectivity Degree ◽  
Spatial Morphology

The spatial morphology of waterfront green spaces helps generate cooling effects to mitigate the urban heat island effect (UHI) in metropolis cities. To explore the contribution and influence of multi-dimensional spatial indices on the mitigation of UHIs, the green space of the riparian buffer along 18 river channels in Shanghai was considered as a case study. The spatial distribution data of the land surface temperature (LST) in the study area were obtained by using remote sensing images. By selecting the related spatial structure morphological factors of the waterfront green space as the quantitative description index, the growth regression tree model (BRT) was adapted to analyze the contribution of various indexes of the waterfront green space on the distribution of the LST and the marginal effect of blue–green synergistic cooling. In addition, mathematical statistical analysis and spatial analysis methods were used to study the influence of the morphological group (MG) types of riparian green spaces with different morphological characteristics on the LST. The results showed that in terms of the spatial structure variables between blue and green spaces, the contribution of river widths larger than 30 m was more notable in decreasing the LST. In the case of a larger river width, the marginal effect of synergistic cooling could be observed in farther regions. The green space that had the highest connectivity degree and was located in the leeward direction of the river exhibited the lowest LST. In terms of the spatial morphology, the fractional cover values of the vegetation (Fv) and area (A) of the green space were the main factors affecting the cooling effect of the green space. For all MG types, a large green patch that had a high green coverage and connectivity degree, as well as was distributed in the leeward direction of the river, corresponded to the lowest LST. The research presented herein can provide methods and development suggestions for optimizing spatial thermal comfort in climate adaptive cities.

Microclimatic Effects of Green Facades in Urban Environment

2014 ◽  
Vol 899 ◽  
pp. 415-420
Author(s):  
Flóra Szkordilisz
Keyword(s):  
Large Scale ◽  
Green Spaces ◽  
Urban Vegetation ◽  
Heat Island ◽  
Prevailing Wind ◽  
Negative Effects ◽  
Urban Green Spaces ◽  
Street Tree ◽  
Prevailing Wind Direction ◽  
Urban Heat

The processes of the last decades’ – such as climate change, growth of cities, and the decreasing of urban green spaces – increase the risk of overheating during the summer. The significance of vegetable shading is, that through evapotranspiration it can minimise the risk of overheating and the negative effects of urban heat island. Although there are some previous data about the effect of vegetation, there are still questions in the scope of the microclimatic and energetic effect of vegetation planted in front of the façades. The effectiveness of urban vegetation varies on a large scale depending on environmental conditions. For example the effect of street tree lines on wind speed changes in relation with the angle of the axis of the street and the prevailing wind direction. The mentioned dilemma is a major issue of planning urban ventilation. That is why more precise calculations are needed to be able to use urban vegetation properly and most effectively. Scientific research should provide a background for quantifying the effect of urban vegetation so that designers could be helped to use more confidentially the vegetation as an important “building element” in the build-up environment. In order to facilitate vegetable shading the paper presents an attempt for the quantitative evaluation of green facades.

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