چکیده:
Urbanization is developing unprecedentedly on a global scale. One of the chief repercussions of urbanization, caused by man-made alterations in land-use/land-cover (LULC) , is the formation of urban heat islands. Albeit, differences among landscape structures and its accompanied effects on the environment are mostly neglected. Accordingly, the main objective of this study is to survey the various effects of LULC on urban heat island in terms of landscape metrics. For this purpose, Landsat-8 images and land-use maps extracted for the study region (Urmia) were employed. Landscape metrics were calculated from Landsat images with spatial resolution of 30 m for five varying scenarios (residential lands of five-floors and more, residential lands with less than five-floors, administrative-commercial lands, industrial lands, educational and health lands). The metrics were then investigated with respect to two types of land-cover (vegetation and impervious lands). Analysis results indicate that following industrial use, administrative-commercial use is the most significant factor contributing to the formation of heat islands. Results also stipulated the indirect relationship between vegetation and land surface temperature for all scenarios, with the exception of industrial use; in contrast impervious surfaces showed a direct relationship with earth temperature. Study results further determined the effectiveness of human factors in conjunction with LULC as amongst key factors influencing urban LST. Finally, the study specified how different effects of LULC on heat island of Urmia can be well defined with reference to landscape metrics.
خلاصه ماشینی:
ir Desert 24-2 (2019) A Survey of Landscape Metrics and Land-use/land-cover Structures on Urban Heat Islands Surface: A Case Study on Urmia City, Iran Y.
Keywords: Landsat Images; Landscape Metrics; Land-use/Land-cover; Urban Heat Islands; Urmia city 1.
Remote sensing images have also been considered as satisfactory sources of information for the preparation of thermal maps and other applications regarding the accurate examination of climate change, urban heat island and land-use in urban and suburban areas, due to their various features including extensive and continuous coverage, regular time series, timeliness, and the ability to obtain information in the reflectance and thermal fields of electromagnetic waves (Hakimzadeh Ardakani and Vahdati, 2018; Weng et al.
The results indicate the effective role of vegetation in modulating land surface heat and how land-use changes caused by urbanization lead to the increase of urban temperatures.
Different effects of LULC on land surface temperature changes were examined for summer using images from July 18th, 2015, mainly due to the fact that the heat island of Urmia peaks in intensity during this season.
Vegetation cover, due to its relationship with impervious surfaces is an effective factor in reducing the city's average temperature, however it should be noted that the surface area of this land-cover is significantly important in reducing the urban thermal island (Chang et al.
The results of LULC analysis have shown that in addition to impervious lands, which have led to an increase in the average temperature of Urmia, the existence of industrial lands, high population density in administrative-commercial applications, and the effect of height and geometry in FFM use have also been major contributors to the creation of thermal island.