THE NASA SURFACE WATER OCEAN TOPOGRAPHY (SWOT) MISSION WILL BE LAUNCHED IN 2021 TO PROVIDE UNPRECEDENTED OBSERVATIONS OF GLOBAL RIVERS WITH WIDTHS GREATER THAN 50-100 METERS. THE NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA) NATIONAL WATER MODEL (NWM) WHICH WILL BECOME THE STANDARD FOR OPERATIONAL HYDROLOGIC FORECASTING IN THE UNITED STATES IN A FEW YEARS PROVIDES STREAMFLOW FORECASTS FOR 2.7 MILLION CHANNEL REACHES WITHIN THE CONTINENTAL UNITED STATES. HOWEVER ONLY 0.25% OF THESE CHANNEL REACHES ARE CURRENTLY BEING INITIALIZED WITH ACTUAL OBSERVATIONS GATHERED BY APPROXIMATELY 7000 IN-SITU STREAM GAUGES. THE SWOT MISSION HAS THE CAPABILITY TO INCREASE THE SPATIAL COVERAGE OF STREAMFLOW OBSERVATIONS AND PROVIDE MEASUREMENTS FROM A UNIFORM OBSERVATIONAL PLATFORM BUT NO STEPS HAVE BEEN MADE TO PREPARE SWOT MEASUREMENTS FOR ASSIMILATION INTO THE OPERATIONAL NWM. THIS PROJECT WHICH ALIGNS WITH MULTIPLE NASA EARTH SCIENCE RESEARCH PROGRAM OBJECTIVES WILL DEVELOP THE CAPABILITIES AND METHODOLOGY TO ASSIMILATE SYNTHETIC SWOT OBSERVATIONS INTO THE OPERATIONAL NWM USING AN ENSEMBLE KALMAN FILTER (ENKF) SO THAT SWOT DATA CAN BE USED OPERATIONALLY SHORTLY AFTER LAUNCH. IN DOING SO THIS PROJECT WILL INVESTIGATE SEVERAL CASE STUDIES CORRESPONDING TO RAIN-GENERATED FLOOD EVENTS IN ALASKA TO ANSWER THE FOLLOWING RESEARCH QUESTIONS: (1) DOES THE ASSIMILATION OF SWOT RIVER DISCHARGE IMPROVE STREAMFLOW FORECAST ACCURACY IN GAUGED AND UNGAUGED BASINS (2) TO WHAT EXTENT DOES THE TEMPORAL RESOLUTION OF SWOT OBSERVATIONS DETERMINE SWOT ASSIMILATION IMPACTS AND (3) HOW DOES THE ASSIMILATION OF SWOT RIVER DISCHARGE TO IMPROVE STREAMFLOW FORECASTS IMPACT THE SUBSEQUENT PREDICTION OF INUNDATION AND OTHER HAZARDS? IT IS EXPECTED THAT SWOT DISCHARGE ASSIMILATION WILL IMPROVE STREAMFLOW PREDICTION WHICH IN TURN WILL IMPROVE FLOOD GUIDANCE EMERGENCY MANAGEMENT AND DISASTER RESPONSE.