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Title: Modeling flash flood events in an ungaged semi-arid basin using a real-time distributed model: Fish Creek near Anza Borrego, California

Author
item SCHNAFFNER, M. - National Oceanic & Atmospheric Administration (NOAA)
item Unkrich, Carl
item Goodrich, David - Dave
item TARDY, A. - National Oceanic & Atmospheric Administration (NOAA)

Submitted to: National Oceanic and Atmospheric Administration
Publication Type: Other
Publication Acceptance Date: 3/1/2014
Publication Date: 8/1/2014
Citation: Schnaffner, M., Unkrich, C.L., Goodrich, D.C., Tardy, A. 2014. Modeling flash flood events in an ungaged semi-arid basin using a real-time distributed model: Fish Creek near Anza Borrego, California. National Oceanic and Atmospheric Administration Western Regional Technical Attachment. 14-02, 42 p.

Interpretive Summary: Fast responding headwater basins and canyons pose a significant threat to life and property throughout the semi-arid western United States. The National Weather Service (NWS) of the National Oceanographic and Atmospheric Administration (NOAA) is responsible for providing flash flood warnings to the public. This paper presents the results from the application of the real-time distributed model KINematic runoff and EROsin model (KINEROS2) to the complex terrain of the Fish Creek basin located at the southern end of the Vallecito Mountains and the Carrizo Badlands. In operations, KINEROS2 uses real-time radar-rainfall data to produce a forecast hydrograph. Due to inherent uncertainties with forecasting for ungaged locations, the forecast will be qualitative in nature (no flooding, minor flooding, moderate flooding, major flooding, or record flooding). The model was calibrated using a series of rainfall events representing a full range of flow outcomes from below flood stage up to record flood. Calibration was successful in reproducing all flows regardless of magnitude. A simple calibration scheme of one calibration for low flows through low-end major flooding and another for higher end major floods through record flooding was employed. The timing and magnitude of the peak flow is useful information currently not available using current NOAA/NWS flash flood forecasting methodologies available at the Weather Forecast Office.

Technical Abstract: Fast responding headwater basins and canyons pose a significant threat to life and property throughout the semi-arid western United States. This paper presents the results from the application of the real-time distributed model KINematic runoff and EROsin model (KINEROS2) to the complex terrain of the Fish Creek basin located at the southern end of the Vallecito Mountains and the Carrizo Badlands. In operations, KINEROS2 uses real-time radar data to produce a forecast hydrograph. Due to inherent uncertainties with forecasting for ungaged locations, the forecast will be categorical in nature (no flooding, minor flooding, moderate flooding, major flooding, or record flooding). The model was calibrated using a series of rainfall events representing a full range of flow outcomes from below flood stage up to record flood. Calibration was successful in reproducing all flows regardless of magnitude. A simple calibration scheme of one calibration for low flows through low-end major flooding and another for higher end major floods through record flooding was employed. The timing and magnitude of the peak flow is useful information currently not available using current NOAA/NWS flash flood forecasting methodologies available at the Weather Forecast Office.