Evaluation of surface urban heat island (SUHI) effect on coastal zone: The case of Istanbul Megacity

Urban expansion and development have greatly altered Land Use/Cover (LULC) structure in worldwide scale. Changing LULC types have some important side effects on evaporation and transmittance processes. Atmospheric air-land interactions are greatly influenced by LULC types. Since, the increasing rate of impervious surfaces has led to abnormal patterns in Land Surface Temperature (LST). Areas with relatively high urbanization rate such as coastal cities will probably more vulnerable to unwanted impacts of varying LSTs. Attractiveness character of the coastal regions due to potentially high living comfort in terms of transportation, recreation and industrialization is the main factor triggering fluctuations in LST values. Formation of SUHI is closely related to LST patterns and so as to LULC structure. Unplanned expansion of impervious surface class of LULC may potentially increase the chance of SUHIs occurrence along the coastal zone. Remote sensing technology is a valuable tool for determination of LULC as well as quantification of SUHI effect on a given land surface. In this study temporal evaluation of SUHI effect in a coastal metropol city is investigated. Landsat TM/ETM + data covering 1984-2011 period was used for determination of position, coverage and magnitude of SUHI phenomena in the city of Istanbul. SUHI density maps are obtained with a proposed approach and simultaneously Support Vector Machine (SVM) algorithm is used to produce LULC maps of the same region. Furthermore produced temporal data pool is used to find statistical relations between SUHI intensity and LULC maps using spatial random sampling methodology. Temporal trends of SUHI and LULC are also evaluated for the study area. Finally, SUHI character of megacity of Istanbul is comprehensively documented. (C) 2015 Elsevier Ltd. All rights reserved.