The effects of land cover on urban heat islands in Bangkok Metropolis

Abstract

Surface radiant temperature, transformed vegetation index (TVI), and land use / land cover type derived from Landsat TM were used for urban heat island assessment throughout Bangkok Metropolis. Relationship between surface radiant temperature and TVI were determined on nine land use / land cover classes consisted of (1) residential area, (2) industrial area, (3) residential and industrial mixed area, (4) vegetation area, (5) harvested paddy-field, (6) bare soil, (7) growing paddy field or marsh land, (8) aquaculture pond, and (9) water body. The results revealed an inverse relationship between TVI and surface temperature and the variation of these values on different land surface properties. The high TVI and low surface temperature corresponded to vegetation area, while the low TVI and high surface temperature corresponded to the built- up surface and bare soil. The study showed that the presence of vegetation could cool down the surface temperature in such land covers type. The decreasing of vegetation and the extension of built-up area can raise surface temperature. When considered the difference between TVI and surface temperature with respect to urban and rural area. It was found that the values of TVI in urban area were lower than those in rural area for 2.15% and 1.18% in 1988 and 1997, respectively, whereas the surface radiant temperature in urban area were higher than those in rural area by 1.71°c and 1.53 °c in 1988 and 1997, respectively.