LAND SURFACE TEMPERATURE VARIATION AND LAND COVER CHANGES BASED ON SATELLITE IMAGERY DATA

摘要

Urban area is a complex eco-environment involving a variety of anthropogenic activities. Its sustainable development is affected by many factors, such as topographical appearance, hydro-meteorological environment, and social economics. Due to urban sprawl and less vegetation, urban areas often exhibit higher thermal signatures than less disturbed rural areas. Thermal signatures represent the thermal status resulting from energy balance at land-air interface. In this study, Land Surface Temperatures (LSTs) are retrieved from Landsat TM, ETM, and OLI & TIRS (Thematic Mapper, Enhanced Thematic Mapper, and Operational Land Imager & Thermal Infrared Sensor, respectively) and serve as basis to derive ecological thermal index for assessing ecological dynamics in years 1989, 2003, and 2014. The Thua Thien - Hue Province, Vietnam, is chosen as a study area because it is a coastal province and has been experiencing with natural disaster, deforestation, and rapid urbanization. Its LST is found to increase by 0.7 °C and 1.5 °C for the 1989-2003 and 2003-2014 periods, respectively. Thermal environment index maps are utilized to categorize ecological conditions into six levels (excellent, good, normal, bad, worse, and worst). To demonstrate urban development a major contributor to thermal anomaly, correlation between LST and Normalized Difference Build-up Index (NDBI) is analysed. The correlation is found to be positive as expected with coefficient values 0.87, 0.89, and 0.84 for 1989, 2003, and 2014, respectively. In contrast, LST-Normalized Difference Vegetation Index (NDVI) is found negatively correlated with corresponding coefficient values -0.81, -0.81, and -0.76, indicating that vegetation reduces thermal intensity. In addition, areas associated with excellent, good, and normal thermal environmental levels are decreased over the same period of time frames 1989-2003 and 2003-2014.