Present status and historical changes of urban green space in Dhaka city, Bangladesh: A remote sensing driven approach

Abstract

Green spaces are a significant aspect of a healthy urban environment. Dhaka is losing its greener share for decades. However, a quantitative estimation is needed to evaluate the pattern of changes in green space for proper urban management. This study analyzed green spaces of Dhaka city between 1989 and 2020 (30 years) using GIS and Remote Sensing. 30-meter resolution Landsat satellite images were used for the analysis. Supervised classification was performed to calculate the total change in vegetation and differentiation in healthy and non-healthy green spaces were done using NDVI analysis. Results showed that the total decrease in vegetation of the study area was 56% from 1989 to 2020. However, in 1989 the healthy green space was 17% which decreased to only 2% in 2020. Thus, a severe healthy green space loss was detected (−88.24%). The share of urban land was found to be 82% of the total study area in 2020, which was only 59% in 1989. In conclusion, this study confirms the diminishing state of healthy green space in Dhaka city which is not suitable for a healthy urban environment. It is crucial to properly manage and restore Dhaka city's green spaces and give more consideration to ensure healthy urban area in the future policy making.