Abstract
Abstract Dhaka, the capital of Bangladesh, has been experiencing severe water-logging and urban flooding in the last few decades. In this paper, we estimate the peak storm runoff of Hatirjheel-Begunbari canal – the largest drainage system of the city – under different operational, land use and climate scenarios (2013, 2025 and 2040). Our method includes digital elevation model (DEM) reconditioning, watershed delineation, and development of future land use scenario. We apply HEC-RAS to check the adequacy of Begunbari canal cross-sections to carry peak runoff for the scenarios considered here. The Hatirjheel-Begunbari system is found to drain stormwater from ∼25% of the city. Within the system, built-up areas are increasing linearly by 0.8 Km2/year, whereas water body and wetlands are decreasing exponentially, which might increase the runoff coefficient by 11% in 2040 relative to 2013. Climate-induced change in rainfall intensity along with land-use change show three times higher runoff in 2040 than in 2013. Around 58% of canal cross-sections appear to be overflown at both banks while carrying a 5-year return period peak runoff under the 2013 scenario. For future scenarios, all sections seem to cause an overflow, which is alarming.
Highlights
IntroductionThe capital city of Bangladesh, is one of the top megacities in the world. The current population of Dhaka city is over 8.5 million
Dhaka, the capital city of Bangladesh, is one of the top megacities in the world
The reconditioned digital elevation model (DEM) seems to reflect the topographic features of the study area better than the unconditioned DEM (Figure 2(a)), which allows us to delineate a more representative watershed boundary for the drainage system
Summary
The capital city of Bangladesh, is one of the top megacities in the world. The current population of Dhaka city is over 8.5 million. Even a little rain inundates certain areas of the city for several days and causes serious problems including disruption of traffic movement and normal life, damage to structures and infrastructure, and destruction of vegetation and aquatic habitats (Alam & Rabbani ; Barua & Van Ast ; Mowla & Islam ). This stormwater becomes polluted as it mixes with solid waste, clinical waste, silt, contaminants, and domestic wastes and turns into a health hazard. In 2019, the city struggled with the worst outbreak of dengue fever, a mosquito-borne viral infection, affecting nearly 60,000 people (Mone et al )
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