台中地區土地利用與都市熱島效應之時空變遷分析

Abstract

由於人類活動與過度的開發行為，導致都市內部氣溫調節機制漸漸失靈，土地利用類型改變造成地表溫度變化，亦使都市熱島效應情形加劇，成為都市發展的隱憂；近年來，台中地區都市化與都市成長情形快速，本研究旨在探討台中地區土地利用型態變化，與都市熱島效應之時空變遷情形。 本研究使用Landsat衛星影像，運用遙測技術進行影像分類判釋與地表溫度(Land surface temperature)反演，共選用六個年度的影像(1991、1998、2003、2009、2015與2019)，藉由熱點分析(Getis-Ord Local G-Statistic)量化各年度之地表溫度冷熱區分布範圍與移動情形；而後將地表溫度與常態化差異植生指標(NDVI)、常態化差異建物指標(NDBI)進行簡單與多元迴歸分析；本研究亦探究不同時期台中地區土地利用變遷情形，並計算平均熱島效應強度變化量，使用ANOVA分析實證土地利用型態改變對溫度變化之影響程度，而後再選取七個重劃區，將其熱島效應平均強度與整體進行比較分析。 本研究結果顯示，近30年間台中地區建成地的成長、草生地的減少，乃變動量較大之類別；以迴歸係數總結台中地區整體熱島效應之影響因子，可推論早期整體地表溫度受植被影響較多，至近年則是人工建物扮演較重要之影響角色；歸納不同時期台中地區土地利用類型變化之空間分布可發現，重大交通建設、重劃區闢建與農田棄耕轉為住宅、工廠等，乃經常出現之變遷型態，大肚台地上植被年季光禿情形，也往往造成大面積的改變，因此，人工鋪面、裸露地與植被之間的土地利用類型轉變，著實在熱島效應強度變動上呈現顯著變化。

The internal temperature regulation mechanism inside cities have gradually failed due to human activities and excessive development behaviors. Land use land cover (LULC) change has relationship to land surface temperature (LST), and it also aggravated urban heat island effect, which has become an anxiety during urban development. Recently, Taichung has a rapid urbanization and urban growth situation. This study aims to explore the multi-temporal changes of LULC and urban heat island effect. In this study, a total of six years of images (1991, 1998, 2003, 2009, 2015 and 2019) were first selected for mapping LULC classification results derived from Landsat 5 TM and Landsat 8 OLI, using several classification processes. Second, using Hot spot analysis (Getis-Ord Local G-Statistic) to quantify the distribution and movement of the hot spot and cold spot areas of LST in each year. Third, LST and the normalized difference vegetation index (NDVI) and the normalized difference building index (NDBI) are analyzed by simple and multiple regression. This study also maps the change of LULC, calculate the mean change of urban heat island intensity (UHII), and use ANOVA to quantify impacts of LULC changes on UHII between two periods. Lastly, choosing several rebuilt-zones in order to compare the mean UHII between rebuilt-zone and the whole research area. The result of this research shows that the growth of built-up land and the decrease of grassland in Taichung area are the categories with large changes in past 30 years. The result of coefficients in regression models could summarize that the overall LST was affected by vegetation in the early years, and artificial structures have played a more important role in recent years. Summarizing the spatial distribution of LULC change during different periods, we find out that major transportation constructions, rebuilt-zones, and conversion of farmland to residential or factory fields are frequently appearing in Taichung area. Also, the vegetation on the DaDu platform often changes in different periods, which always causes large area changed. This study concluded that human activities caused the disappearance of vegetation, which causes a significant change on UHII.