Simulation of a Multi-Week Flood Inundation Event in the Cape Fear River Basin (NC) Using a Tightly Coupled Advanced Hydrologic Land-Surface and Routing Model at 100-Meter Resolution

In the fall of 2018, Hurricane Florence approached the North Carolina coast near Pamlico Sound, slowing down and ultimately drifting south-southwestward before exiting across upstate South Carolina several days later. The long-lasting nature of Florence near and just inland of the southeastern NC coastline created complex hydrologic responses featuring a mixture of higher than normal tides, surge levels up to 10 feet, and torrential rains that, in places, approached 40-inches in event total accumulation. In this paper, we will present results of a re-simulation of the event for the Cape Fear River Basin using a tightly coupled hydrologic/routing and prediction model known as the Baron LIS-NOAH2. LN2 represents a legacy in the approach to such modeling that served as a basis for WRF-Hydro model science as well as the National Water Model, and it remains operational as part of a multi-model decision-support system running across the entire nation of Romania at the National Institute of Hydrology in Bucharest. Our results will focus on the ability of the model to reproduce the long-lived inundation event, and will explore the impact of direct two-way coupling between the stream-routing and overland flow components, something that is not currently possible within either WRF-Hydro or the NWM. We will also provide an early assessment of the ability of the model to capture upstream overbankful flows when the outlet Cape Fear River boundary condition is coupled to higher than normal tides/storm surge.