1D River Hydraulic Model for Operational Flood Forecasting in the Tidal Potomac: Evaluation for Freshwater, Tidal, and Wind-Driven Events

Abstract

The National Oceanic and Atmospheric Administration (NOAA) is working toward improving water forecasts in the river-estuary transition zone. One operationally viable method is to extend one-dimensional (1D) hydraulic models downstream well into the tidal estuarine environment. Recent advances in NOAA’s National Weather Service (NWS) operational software infrastructure have made this method easier to implement. This paper evaluates the strengths and limitations of an unsteady implementation for the tidal Potomac River. The model was calibrated and validated to propagate tidal signals upstream for a wide range of freshwater events. Focusing on water-level gauges near Washington, DC, root-mean-squared error for tide simulation at the Washington Waterfront gauge was 0.05 m (0.16 ft) with a phase error of approximately 2 h. For historic flood events, simulated peak water-level error varied from