Estimation of long term spatiotemporal patterns of land surface temperature in response to land use land cover (LULC) change and formation of urban heat island for Lahore city, Pakistan By Mohsin Ramzan

Abstract

An urban heat island (UHI) is a metropolitan area having high temperature surrounded by area with relatively low temperature formed by absorption of heat from sunlight by construction materials. Thermal remote sensing provides a time synchronous temperature data for comparatively a large area. The aim of this research is to estimate land surface temperature (LST) during summer seasons through remotely sensed data and relate it to UHI corresponding to urbanization. Temporal data of Landsat as well as MET data of temperature and precipitation from 1990 to 2017 were used to identify and analyze the UHIs. Different indices such as NDVI, NDBI, and NDBaI were used to detect and map different types of land use land cover’s (LULC) attributes for quantitative and qualitative image analysis as changes in LULC causes change in reflectance of land surface. Correlation between different parameters such as LST and Air Temperature, built up land, and Indices were investigated. An overall increase of 41% in built up area, 23%, 17% and 0.4% decrease in the area of vegetation, bare land and water was observed from 1992 to 2017 respectively. Comparison of temperature from MET station and satellite image showed an increasing trend in LST (29.5°C to 33.6°C from 1992-2017). The mean LST over different LULCs showed a similar increasing trend but the increase was significant for built up (28.4°C to 35.5°C from 1992-2017) implying the significant effect of urbanization on LST. Based on the existing trend, future trends of LULC and LST were predicted for years 2021, 2025, and 2030 using Markov Model. These changes in LULC and LST in turn have detrimental effects on local as well as global climate, environmental degradation, and water resources. The study will help in understanding and addressing these issues.