Low-lying coastal cities are vulnerable to flooding under the combined impact of storm tide and heavy rainfall. While storm tide or heavy rainfall alone is able to directly cause widespread flooding in coastal areas, often heavy rainfall and storm tide happen concurrently, and the severity of flooding is greatly exacerbated. Current methods for understanding flood risk and mapping floodplains normally does not clearly communicate either the individual or combined impact of these two flooding mechanisms. Flood mitigation strategies typically target either rainfall-driven flooding (e.g., stormwater controls) or tidally-driven flooding (e.g., flood walls and tide gates). Thus, better understanding and communicating the individual and combined flood risk resulting from these two mechanisms can be important to improving flood resilience. To address this need, this study presents tools and methods for floodplain mapping in coastal urban environments were rainfall and storm tide driven flooding can be better understood and communicated. The approaches are demonstrated for a watershed in Norfolk, VA, USA as a case study system using a 1D pipe/2D overland flow hydrodynamic model built for the watershed. Storm tide and heavy rainfall events with return periods varying from 1 to 100-year were designed based on historical observations and combined into a series of compound storm scenarios. Then these compound storm scenarios were simulated using the hydrodynamic model for simulating flow through both the land surface and underground pipe network systems. Results show how the capacity of the drainage system, and therefore flood risk reduction, is sensitive to storm tide levels, even for less extreme events with a 1-year return period. The model also provides new insights into the role of stormwater infrastructure in exacerbating flooding risk within communities during high sea level conditions. Results demonstrate how dividing the floodplain into different regions based on the dominant flooding mechanism (rainfall vs. storm tide) makes it possible to better target mitigation strategies to improve flood resilience. To this end, a transition zone index (TZI) is presented to help decision makers identify the change from rainfall-driven to tide-driven flooding for locations within a watershed. Finally, we demonstrate how different flood mitigation strategies can be tested using this modeling approach to better understand their impact on increasing flood resilience within the system for portions of the floodplain impacted by rainfall-driven and tidal-driven flooding.