Changes in urbanization and urban heat island effect in Dhaka city

Abstract

The study aimed to assess the changes in urban areas and UHI effects in Dhaka city, Bangladesh, from 2001 to 2017, using Moderate Resolution Imaging Spectroradiometer (MODIS) daily day- and nighttime land surface temperature (LST) data from 2001 to 2017. The expansion of the city was calculated using the city clustering algorithm (CCA). The temperature of the identified urbanized area was analyzed and compared with the adjacent regions. The changes in urban temperature were estimated using non-parametric statistical methods. The results showed that Dhaka city’s land surface area has grown by 25.33% and its inhabitants by 76.65% during 2001–2017. Urban expansion and dense settlements caused an increase in average temperature in some areas of Dhaka city nearly 3 °C compared to that at its boundary. The day and night temperature differences at Dhaka city’s warmest location and the coolest point outside the city were nearly 7 °C and 5 °C, respectively. The city’s annual average day- and nighttime temperatures was increasing at a rate of 0.03 °C and 0.023 °C/year over the period of the last 17 years. The rising temperature would increase the UHI effect in the future, which, combined with high humidity, may cause a significant increase in public health risk in the city if mitigation practices are not followed.