The effects of unplanned land use and heavy seasonal rainfall on the storm-water drainage in Dhaka metropolitan city of Bangladesh

The capital city of Bangladesh, Dhaka, faces several challenges including significant rainwater congestion. With the holistic depiction of the current status, this study quantified rainfall, estimated land cover change and analyzed the drainage system in the western part of Dhaka. Statistical analysis and logarithmic graph fitting methods were used to develop a strong correlation between short-duration and daily rainfall. Land cover maps from 1990 to 2020 were generated using supervised classification in ERDAS IMAGINE, and the future land cover was predicted using the Terrset software with the CA Markov method. This research found that the build-up region increased by about 70% during the last 30 years while about 15.64 km2 of wetland was encroached during the past 15 years leading to the failure of existing drainage network. The assessment of rainfall demonstrated that the extreme events aggravated the issue. Restoration of natural canals is required for activating proper drainage system in the city.

Automated summary

This study addresses the challenges faced by Dhaka, the capital city of Bangladesh, including rainwater congestion, by quantifying rainfall, estimating land cover change, and analyzing the drainage system in the western part of the city. The research establishes a strong correlation between short-duration and daily rainfall using statistical analysis and logarithmic graph fitting methods. Land cover maps from 1990 to 2020 were generated to examine changes, and the future land cover was predicted. The study finds that the build-up region has increased by 70% in the past 30 years, while the encroachment of wetlands has caused the failure of the drainage network.