Operational / Forecast Ensemble Flood Mapping

Dark-blue shows agreement between all of the flood ensemble members. Light blue indicates where only some of the ensemble members indicate flooding to occur.
Forecast weather and streamflow models account for uncertainty by utilizing multi-member ensembles. Utilizing each member of the weather ensemble, flow models translate weather information into multiple streamflow simulations for each stream reach. However, when flood maps are generated only a single flow rate is chosen for each stream reach and a single flood map is generated. The emphasis of this project is to develop a methodology to create ensemble flood maps for use in continental-scale forecasting frameworks. In so doing, uncertainty in weather/flow forecasts can be realized through the differences in expected flood extents. The figure shows the method for generating operational (forecast) flood maps using flow rates from a 21-member ensemble.