RELATIONSHIP OF LAND USE WITH THE SURFACE TEMPERATURE: A CASE STUDY IN KANDY CITY, SRI LANKA

Abstract

Satellite remote sensing is very popular in gathering data for geographical information systems (GISs) especially in climatology. The relationship of land surface temperature (LST) with the land use is vital in studies related to urban heat islands (UHIs). In order to study this relationship further, this research was conducted for Kandy city, Sri Lanka between 2015 and 2019. Kandy is a highly urbanized tropical mountain city situated at an elevation of 465 m. The data source used for this study is the Landsat 8 data for dry seasons. The land surface temperature (LST) for five years was retrieved and urban functional based land use zones and gradient analysis methods were used to figure out the spatial pattern of LST in the study area. In order to analyze the surface temperature with the land use; normalized difference vegetation index (NDVI) and normalized difference built-up index (NDBI) were used. The results revealed that, from 2015 to 2019 the average temperature of KMC which is nearly 26.6 ◦C by March 2015 is increased by 3.5 ◦C which is up to 30.1 ◦C by March 2019. From zonal statistics it is observed that the lowest LST were obtained at forests, mixed agriculture areas, grass lands and water bodies; highest LST were obtained in banking, community, commercial and transportation areas. To further study the LST patterns multiple ring buffers with 200 m distance were used from the center of the city towards outside. The results showed that the highest temperature is at the city’s center and getting further from the city towards suburbs the temperature decreases. The LST maps were compared with the NDVI and NDBI maps, it showed that the hot spots in NDVI maps are cold spots LST maps; the hot spots NDBI maps are also hot spots in LST maps and vise versa. In conclusion LST and NDVI have a negative correlation while LST and NDBI have a positive correlation. Protecting the green cover and improving the urban vegetation are measurements to be taken in order to monitor the rise of temperature in urban areas.