The citys built-up area doubled between 1991 and 2018, indicating frenzied construction activity, according to a study by some researchers. In 1991, the built-up area covered roughly 173 sq km; but by 2018, it increased to 346 sq km.
Changing land use patterns and urban heat island effect created has led to a 2 degree Celsius increase in Average temperatures during this period.
The study, done using satellite imagery, found Mumbai lost 81% of its open land (barren spaces without vegetation), 40% green cover (forests and scrublands) and approximately 30% of its water bodies (lakes, ponds and floodplains).
The study used satellite imagery (USA-NASA Landsat datasets freely available) and the authors studied 603 sq km of Mumbai region (city and suburbs) to understand landuse and land-cover changes, difference in maximum, minimum and average temperatures (for urban heat island intensity), land surface temperatures, changes in vegetation cover versus urban built-up density between 1991 and 2018. The findings were represented in the form of high resolution maps and attempted to enhance urban planning and policy decisions by mitigating the Urban Heat Island effect.