Abstract: Urban hydrological models are widely used in urban water management. Compared with a hydrological-hydrodynamic model, urban hydrological models always show some limitations for estimating inundated area rapidly and therefore need to be enhanced. In this research, an enhanced inundation model which considers the feedback of water from lower depression element was developed and coupled to the SWMM model to simulate inundated areas in the Tiantang River basin in Beijing. A comparison with the results from a 2-D hydrodynamics model obtained in previous study showed that the enhanced model can quickly and accurately estimate the depth of inundation. The design standard of flood discharge capacity in the Tiantang River basin is lower than 20-year return period, and high-flood-risk areas are concentrated in downstream sections of the river and around the confluence of Tianting River and the Tianying and Yongbao channels. Flood risk in these downstream areas is also likely to increase with the development of new airports in the Tiantang River basin. This research proposes a new method to estimate urban inundation.