تأثير الگوهاي سيماي سرزمين بر تغييرات دماي شهري در همدان

The Effect of Landscape Pattern on Urban Temperature Changes in Hamadan

ﺷﻬﺮﺳﺎزي و ﻣﻨﺎﻃﻖ ﺷﻬﺮي اﺛﺮ ﻗﺎﺑﻞ ﺗﻮﺟّﻬﯽ ﺑﺮ آبوﻫﻮاي ﻣﺤﻠّﯽ و ﺟﻬﺎﻧﯽ دارﻧﺪ. ﯾﮑﯽ از ﻣﻬـﻢ ﺗـﺮﯾﻦ اﯾﻦ اﺛﺮات، ﺗﻐﯿﯿﺮات دﻣﺎي ﺳﻄﺢ ﺷﻬﺮي اﺳﺖ ﮐﻪ ﺷﺎﻣﻞ ﺟﺰاﯾﺮ و ﭼﺎﻟﻪﻫﺎي ﺣﺮارﺗـﯽ در ﺳـﻄﺢ ﺷـﻬﺮ ﻣﯽﺷﻮد. ﻧﻮﺷﺘﺎر ﭘﯿﺶ رو ﺑﺎ ﻫﺪف ﺑﺮرﺳﯽ ﺗﻐﯿﯿﺮ اﻟﮕﻮﻫـﺎي ﺳـﯿﻤﺎي ﺳـﺮزﻣﯿﻦ و ﮐـﺎراﯾﯽ ﺳـﻨﺠﻪ ﻫـﺎي ﺳﯿﻤﺎي ﺳﺮزﻣﯿﻦ در ﺗﺤﻠﯿﻞ ﺗﻐﯿﯿﺮات دﻣﺎي ﺳﻄﺢ ﺷﻬﺮي ﺑﺎ اﺳﺘﻔﺎده از ﺗﺼﻮﯾﺮ ﻣـﺎﻫﻮاره اي ﻟﻨﺪﺳـﺖ 8 در ﻣﺤﺪودة ﺷﻬﺮﺳﺘﺎن ﻫﻤﺪان ﺻﻮرت ﮔﺮﻓﺘﻪ اﺳﺖ. ﺑﻪ اﯾﻦﻣﻨﻈﻮر ﭘﺲ از ﻣﺤﺎﺳﺒﮥ دﻣﺎي ﺳﻄﺢ زﻣﯿﻦ ﺟﺰاﯾﺮ و ﭼﺎﻟﻪﻫﺎي ﺣﺮارﺗﯽ ﻣﺸﺨّﺺ ﺷـﺪ، ﮐـﺎرﺑﺮي ﻫـﺎي ﻣﻮﺟـﻮد در اﯾـﻦ ﻣﻨـﺎﻃﻖ ﺷﻨﺎﺳـﺎﯾﯽ ﺷـﺪه و درﻧﻬﺎﯾﺖ ﺳﻨﺠﻪﻫﺎي ﺳﯿﻤﺎي ﺳﺮزﻣﯿﻦ در ﺳﻄﺢ ﮐﻼس و ﺳﯿﻤﺎي ﺳـﺮزﻣﯿﻦ ﺑـﺎ ﻧـﺮم اﻓـﺰار ﻓﺮاﮔﺴـﺘﺎت اﺳﺘﺨﺮاج ﺷﺪ. ﻧﺘﺎﯾﺞ اﯾﻦ ﻣﻄﺎﻟﻌﻪ ﻧﺸﺎن داد ﮐﻪ ﺑﺎﻻﺗﺮﯾﻦ دﻣﺎ در ﻣﺤﺪودة ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﻣﺮﺑﻮط ﺑﻪ ﭘﻬـ ﺮو ﺧﺎك و ﻓﺎﻗﺪ ﭘﻮﺷﺶ ﮔﯿﺎﻫﯽ ﺑﻮد؛ ﺑﻪﻋﺒﺎرﺗﯽ ﻣﺆﻟّﻔﻪ اﺻﻠﯽ ﭼﺎﻟـﻪ ﻫـﺎي ﺣﺮارﺗـﯽ، ﻟﮑّـﮥ ﮐﺸـﺎورزي اﺳـﺖ درﺣﺎﻟﯽﮐﻪ، ﻟﮑّﮥ ﺧﺎك ﻋﻀﻮ اﺻﻠﯽ ﺗﺸﮑﯿﻞدﻫﻨﺪة ﺟﺰاﯾﺮ ﺣﺮارﺗﯽ اﺳﺖ. راﺑﻄﮥ دﻣـﺎي ﺳـﻄﺢ زﻣـﯿﻦ ﺑـﺎ ﺳﻨﺠﻪﻫﺎ در ﺳﻄﺢ ﺳﯿﻤﺎي ﺳﺮزﻣﯿﻦ ﻧﯿﺰ ﺑﺮرﺳﯽ ﺷﺪ، در ﺟﺰاﯾﺮ ﺑـﯿﻦ دﻣـﺎ و ﺗـﺮاﮐﻢ ﻟﮑـﻪ، ﻫﻤﺒﺴـﺘﮕﯽ ﻣﻨﻔﯽ و در ﭼﺎﻟﮥ ﺣﺮارﺗﯽ؛ ﺑﺮﻋﮑﺲ ﺟﺰﯾﺮة ﺣﺮارﺗﯽ، دﻣﺎ ﺑﺎ ﺳﻨﺠﮥ ﺗﺮاﮐﻢ ﻟﮑﻪ راﺑﻄﮥ ﻣﺜﺒـﺖ و ﻣﻌﻨـﯽ دار و ﺑﺎ ﺳﻨﺠﮥ ﺷﺎﺧﺺ ﺗﺠﻤّﻊ ﻫﻤﺒﺴﺘﮕﯽ ﻣﻨﻔﯽ داﺷﺖ. ﻫﺮﭼﻪ ﭘﯿﻮﺳﺘﮕﯽ ﺑﯿﻦ ﮐﺎرﺑﺮي و اﻟﮕﻮﻫﺎي ﺳﯿﻤﺎي ﺳﺮزﻣﯿﻦ ﺑﯿﺸﺘﺮ ﺑﺎﺷﺪ دﻣﺎ ﭘﺎﯾﯿﻦﺗﺮ و ﻫﺮﭼﻪ ﻗﻄﻌﻪﻗﻄﻌﻪﺷﺪﮔﯽ اﻓﺰاﯾﺶ ﯾﺎﺑﺪ، روي دﻣﺎ ﺗـﺄﺛﯿﺮ اﻓﺰاﯾﺸـﯽ دارد. ﻧﺘﺎﯾﺞ ﺑﯿﺎﻧﮕﺮ آن اﺳﺖ ﮐﻪ دﻣﺎي ﺳﻄﺢ زﻣﯿﻦ در ﺷﻬﺮﺳﺘﺎن ﻫﻤـﺪان ﺗﻨﻬـﺎ ﺗﺤـﺖ ﺗـﺄﺛﯿﺮ ﺗﺮﮐﯿـﺐ ﮐﺎرﺑﺮي و ﭘﻮﺷﺶ ﺳﻄﺢ زﻣﯿﻦ ﻧﯿﺴﺖ؛ ﺑﻠﮑﻪ ﭘﯿﮑﺮهﺑﻨﺪي ﻓﻀﺎﯾﯽ و ﺳﺎﺧﺘﺎر ﺳـﯿﻤﺎي ﺳـﺮزﻣﯿﻦ ﻧﯿـﺰ در آن ﺗﺄﺛﯿﺮﮔﺬار اﺳﺖ.

Urbanization and urbanized areas have a significant impact on local and global climate. One of the most important its effects is surface urban thermal variations (SUTV), including surface urban heat islands (SUHI) and surface urban heat sinks (SUHS). The purpose of this study is to investigate the impacts of landscape pattern changes and the efficiency of landscape metrics in analyzing surface urban thermal variations in Hamadan using Landsat 8 satellite images. Having calculated land surface temperature (LST), the SUHI and SUHS regions were identified, the existing land uses in these areas were classified and finally landscape metrics at class and landscape levels were extracted using FRAGSTATS software. The results showed that the highest temperature in the study area was seen in the areas with no vegetation cover, in other words the main component of SUHS is agriculture patch, while soil patch is the main constituent of SUHI. The relationships between LST and landscape metrics were also examined. LST and patch density (PD) were negatively correlated. In SUHS, in contrast to island heat areas, LST had a negative correlation with AI metrics and had a positive and significant relationship with PD metrics. The higher the consistency between land use and landscape patterns, the lower the temperature and the higher the fragmentation, the higher the temperature effect. The results indicated that land surface temperature in Hamadan is not affected just by land use composition and land cover, LST in Hamadan is not only affected by the combination of land cover, but also the spatial configuration and structure of the landscape is influenced.