Real-Time Total Water Forecasts for the National Capital Region and the Chesapeake Bay

Recent hurricane seasons demonstrated the importance of integrating urban, riverine and coastal model forecasts for total water prediction in coastal and tidal areas. For example, the National Water Model (NWM) brings an unparalleled potential to improve the current flood forecast systems in such environments by providing streamflow forecasts at an unprecedented spatial scale and coverage. Like many US coastal areas, Washington DC and the surrounding communities in MD and VA are vulnerable to multi-flood hazards, subjected to high flood levels from inland precipitation in urban areas, high streamflow from the Potomac and Anacostia river watersheds, as well as tide and surge driven coastal inundation from the Chesapeake Bay. While the National Capital Region is especially vulnerable to these multi-flood hazards, several major cities along the coast are equally or more susceptible to such hazards. This presentation will demonstrate an operational total water forecast system for the Chesapeake Bay region focusing on coastal natural reserves, the tidal Potomac River and the National Capital Region. The Integrated Flood Forecasting System iFLOOD (http://iflood.vse.gmu.edu/) is a scientific experiment to incorporate multi-scale and multi-temporal physical process for total water predictions, including large scale oceanic process, off-shore and near shore waves, estuarine hydrodynamics, coastal processes, wave attenuation by natural features, riverine flows, urban runoff, watershed hydrology, and storm water systems. It combines a multi-model framework (ADCIRC, SWAN, NAM, XBeach, WRF-Hydro, NWM and HEC-RAS2D) that provides several flood forecasting parameters at a range of spatial and temporal scales. This system is currently run 2-4 times a day for short range (3.5 days) and weekly for long-range (30 days) forecasts providing information directly to the Washington-Baltimore National Weather Service Office of Weather Predictions. A web-based user interface provides user-friendly access to flood guidance and real-time model performance evaluation. We expect that this system can demonstrate viable alternatives to the current forecast systems and provide guidance for the new generation of water forecast systems towards a full suite of water budget variables from local to continental scales.