Flood Risk Assessment Using the Updated FEMA Floodplain Standard in the Ellicott City, Maryland, United States

Every Year, flooding causes a calamitous impact on the people, economy, and environment all over the world. In recent years, the flood-related damages have been increasing in the United States regardless of several investments in the flood control measures. Floodplain mapping is an important tool for management that aids in the planning of infrastructures within the floodplain zone. With the magnifying effects of climate change on the hydrological cycle the study of floodplain is becoming a key tool in the water management. Federal Emergency Management Agency has recently updated their floodplain standard as per the presidential executive order 2015 on the Federal Flood Risk Management Standard. This study incorporates the newly updated floodplain mapping standard in the flood risk assessment of approximately 11.2 km stretch of the Patapsco River near Ellicott City. Hydrologic Engineering Center’s River Analysis System (HEC-RAS) with the conjunction of geographical information systems were used in the floodplain analysis. The different return period flows (2, 5, 10, 25, 50, 100, and 500) were used from the frequency analysis. These flows were routed through the selected reach of Patapsco River and the vulnerability assessment of the nearby existing infrastructures was conducted. This study can assist the decision makers and planner for the implementation of flood protection measures near the Ellicott City.