Spatio-Temporal Analysis of LULC Change, UHI intensification in Ludhiana City (2001-2021)

Cities have come a long way from their traditional structures of past to complex structures of today. Majority of population burden in future will be on cities as rapid urbanization is happening. Increasing urbanization has also created problems such as heat island effect responsible for elevating surface temperatures and compromising thermal comfort. This study analyses the spatio-temporal dynamics of Land Use/Land Cover (LULC), Urban Heat Island (UHI) and thermal comfort of Ludhiana city over a twenty-year period from 2001 to 2021. Ludhiana which is an important cultural and industrial hub of north India has experienced rapid urbanization and development. Using Landsat satellite imagery and indices such as Normalized Difference Vegetation Index (NDVI), Normalized Difference Built-up Index (NDBI), Land Surface Temperature (LST), with the help of Google Earth Engine for spatial processing, the study quantifies significant changes in urban morphology and thermal profiles. An attempt has been made to understand the correlation between increasing UHI with decreasing vegetation and increasing built-up. There is a case of strong correlation. Mean LST of various LULC classes were calculated and there is a trend of increasing LST among all LULC classes.  Results indicate an 80.75% increase in built-up area primarily at the expense of vegetation (−82.88%) and waterbodies (−45.39%). Correspondingly, surface temperatures rose notably across all land classes, with built-up zones reaching an average LST of 41.8° C by 2021. There appears to be a case of intense UHI in the major parts of the city which is dispersed along with decrease in thermal comfort within this period.  There is need of sustainable plans for LULC management, along with heat action plans so that there is a conducive environment that promotes public health, climate resilience, decision making involving various stakeholders of the city.