Coastal flooding caused by tropical cyclones has long been a major threat to life,property,and infrastructure in coastal zones.This study assessed the risk of flooding in Chittagong,southeastern Bangladesh,under extreme sea level scenarios caused by high astronomical tides and storm surges.The Jelesnianski typhoon model and the ADvanced CIRCulation hydrodynamic model were used to simulate 91 typhoons that occurred in the Bay of Bengal between 1981 and 2017,and observational data were used for model validation.The inundation model was based on a digital elevation model and a seed spread algorithm,and a geographical information system was used to visualize the flood risk.Under four scenarios,the changes in flood levels caused by sea level rise had no signifi-cant influence on the extent of flooding in Chittagong.At flood levels of 8.82 m(50-year storm surge without sea level rise)and 8.89 m(50-year storm surge with sea level rise),the maximum estimated area of inundation was 11.35 km2.The western coastal and southeastern river coastal plain areas of Chittagong have the highest risk of inundation due to their low-lying terrain.At flood levels of 9.83 m(100-year storm surge without sea level rise)and 9.97 m(100-year storm surge with sea level rise),the maximum simulated flood extent was 36.44 km2.Simulated floodwaters propagated in a south-north direction,and most of the northern areas of the city are at risk of inundation under these scenarios.