Temperature Changes on Land Surface in the Context of Urbanization in Quy Nhon City, Viet Nam

Abstract

Quy Nhon city is a grade 1 city situated in Binh Dinh province, in Viet Nam. Its population was 481.110 inhabitants and it had an urbanization rate of 60% in 2019, while Quy nhon population numbered just 260.000 in 2017. In order to evaluate the relationship between urban heat island and land cover, we used Landsat satellite imagery from 1990 to 2020 to classify the land cover by using the Support Vector Machine learning method (SVM). The classified results were evaluated with the test samples from the field survey. The accuracy is above 77%, which is reliable enough for use in research. To create the surface temperature layer, we used band 6 in the Landsat 5 ETM remote sensing imagery and bands 10, 11 in the Landsat 8 imagery. The results were calculated the surface temperature for the study area. The study carried out statistics of surface temperature value with land cover. The results show that Quy Nhon city has become warmer since 2005, which witnessed a significant increase, compared with roughly 4 degrees in 1996 and around 9 degrees in 1990. And the temperature in the urban land area is between 30 and 35 degrees. During this period, the classification results show that urban land has rapidly expanded. Especially from 2005 up to now, Quy Nhon city has witnessed a strong urban expansion, agricultural land, and water surface have been changed into urban land. To determine the area of urban heat islands we used the urban heat index (UHI). The results show that the heat island phenomenon increases with urbanization in the city and tends to increase over the years. This research result is a practical basis to propose suitable spatial and landscape planning solutions for the city, towards green and sustainable urban development.