RADAR-ASSISTED REAL-TIME FLOOD FORECASTING

A hydrometerological study of the Yockanookany watershed in Mississippi was conducted to demonstrate the use of National Weather Service (NWS) radar and rain gage data for flood forecasting. Weather radar scenes were recorded at approximately 10 min intervals using a Kavouras Triton X computer for three storms in 1986 by the U.S. Army Corps of Engineers. The NWS recorded precipitation hourly at five gaging stations in or near the watershed. A U.S. Geological Survey (USGS) stream gage was located at the watershed outlet. Calibrated weather radar is shown to be effective for flood forecasting. Both the modified Brandes and Kriging calibration techniques gave good results. The most consistent results were achieved when the rainfall intensity was computed from six radar scenes per hour. Storm routing can be effective in forecasting precipitation several hours in advance, if conducted when the storm intensity is relatively constant. The proposed storm translation method is effective for stratiform-type storms with motion trajectories and intensities almost constant, and should not be used in forecasting severe convective-type storms.